Viruses which lack a complete genome so that they cannot completely replicate or cannot form a protein coat. Some are host-dependent defectives, meaning they can replicate only in cell systems which provide the particular genetic function which they lack. Others, called SATELLITE VIRUSES, are able to replicate only when their genetic defect is complemented by a helper virus.
Acquired defect of cellular immunity that occurs in mice infected with mouse leukemia viruses (MuLV). The syndrome shows striking similarities with human AIDS and is characterized by lymphadenopathy, profound immunosuppression, enhanced susceptibility to opportunistic infections, and B-cell lymphomas.
Viruses which enable defective viruses to replicate or to form a protein coat by complementing the missing gene function of the defective (satellite) virus. Helper and satellite may be of the same or different genus.
The process of intracellular viral multiplication, consisting of the synthesis of PROTEINS; NUCLEIC ACIDS; and sometimes LIPIDS, and their assembly into a new infectious particle.
Species of GAMMARETROVIRUS, containing many well-defined strains, producing leukemia in mice. Disease is commonly induced by injecting filtrates of propagable tumors into newborn mice.
A phenomenon in which infection by a first virus results in resistance of cells or tissues to infection by a second, unrelated virus.
Relating to the size of solids.
The infective system of a virus, composed of the viral genome, a protein core, and a protein coat called a capsid, which may be naked or enclosed in a lipoprotein envelope called the peplos.
Deoxyribonucleic acid that makes up the genetic material of viruses.
Ribonucleic acid that makes up the genetic material of viruses.
Established cell cultures that have the potential to propagate indefinitely.
The functional hereditary units of VIRUSES.
Proteins found in any species of virus.
The complete genetic complement contained in a DNA or RNA molecule in a virus.
The assembly of VIRAL STRUCTURAL PROTEINS and nucleic acid (VIRAL DNA or VIRAL RNA) to form a VIRUS PARTICLE.
Viruses whose genetic material is RNA.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
A test used to determine whether or not complementation (compensation in the form of dominance) will occur in a cell with a given mutant phenotype when another mutant genome, encoding the same mutant phenotype, is introduced into that cell.
The type species of ORTHOPOXVIRUS, related to COWPOX VIRUS, but whose true origin is unknown. It has been used as a live vaccine against SMALLPOX. It is also used as a vector for inserting foreign DNA into animals. Rabbitpox virus is a subspecies of VACCINIA VIRUS.
Specific molecular components of the cell capable of recognizing and interacting with a virus, and which, after binding it, are capable of generating some signal that initiates the chain of events leading to the biological response.
Process of growing viruses in live animals, plants, or cultured cells.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
A general term for diseases produced by viruses.
A species of POLYOMAVIRUS originally isolated from Rhesus monkey kidney tissue. It produces malignancy in human and newborn hamster kidney cell cultures.
The expelling of virus particles from the body. Important routes include the respiratory tract, genital tract, and intestinal tract. Virus shedding is an important means of vertical transmission (INFECTIOUS DISEASE TRANSMISSION, VERTICAL).
Viruses whose nucleic acid is DNA.
The outer protein protective shell of a virus, which protects the viral nucleic acid.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
Proteins that form the CAPSID of VIRUSES.
The type species of MORBILLIVIRUS and the cause of the highly infectious human disease MEASLES, which affects mostly children.
Viruses parasitic on plants higher than bacteria.
The type species of the genus ORTHOHEPADNAVIRUS which causes human HEPATITIS B and is also apparently a causal agent in human HEPATOCELLULAR CARCINOMA. The Dane particle is an intact hepatitis virion, named after its discoverer. Non-infectious spherical and tubular particles are also seen in the serum.
Substances elaborated by viruses that have antigenic activity.
The type species of ALPHAVIRUS normally transmitted to birds by CULEX mosquitoes in Egypt, South Africa, India, Malaya, the Philippines, and Australia. It may be associated with fever in humans. Serotypes (differing by less than 17% in nucleotide sequence) include Babanki, Kyzylagach, and Ockelbo viruses.
A species of CERCOPITHECUS containing three subspecies: C. tantalus, C. pygerythrus, and C. sabeus. They are found in the forests and savannah of Africa. The African green monkey (C. pygerythrus) is the natural host of SIMIAN IMMUNODEFICIENCY VIRUS and is used in AIDS research.
DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition.
The type species of LENTIVIRUS and the etiologic agent of AIDS. It is characterized by its cytopathic effect and affinity for the T4-lymphocyte.
A subtype of INFLUENZA A VIRUS with the surface proteins hemagglutinin 1 and neuraminidase 1. The H1N1 subtype was responsible for the Spanish flu pandemic of 1918.
A CELL LINE derived from the kidney of the African green (vervet) monkey, (CERCOPITHECUS AETHIOPS) used primarily in virus replication studies and plaque assays.
The type species of LYSSAVIRUS causing rabies in humans and other animals. Transmission is mostly by animal bites through saliva. The virus is neurotropic multiplying in neurons and myotubes of vertebrates.
An amino acid intermediate in the metabolism of choline.
A subtype of INFLUENZA A VIRUS comprised of the surface proteins hemagglutinin 5 and neuraminidase 1. The H5N1 subtype, frequently referred to as the bird flu virus, is endemic in wild birds and very contagious among both domestic (POULTRY) and wild birds. It does not usually infect humans, but some cases have been reported.
Proteins coded by the retroviral gag gene. The products are usually synthesized as protein precursors or POLYPROTEINS, which are then cleaved by viral proteases to yield the final products. Many of the final products are associated with the nucleoprotein core of the virion. gag is short for group-specific antigen.
The type species of VESICULOVIRUS causing a disease symptomatically similar to FOOT-AND-MOUTH DISEASE in cattle, horses, and pigs. It may be transmitted to other species including humans, where it causes influenza-like symptoms.
Release of a virus from the host cell following VIRUS ASSEMBLY and maturation. Egress can occur by host cell lysis, EXOCYTOSIS, or budding through the plasma membrane.
A subtype of INFLUENZA A VIRUS comprised of the surface proteins hemagglutinin 3 and neuraminidase 2. The H3N2 subtype was responsible for the Hong Kong flu pandemic of 1968.
A species of FLAVIVIRUS, one of the Japanese encephalitis virus group (ENCEPHALITIS VIRUSES, JAPANESE). It can infect birds and mammals. In humans, it is seen most frequently in Africa, Asia, and Europe presenting as a silent infection or undifferentiated fever (WEST NILE FEVER). The virus appeared in North America for the first time in 1999. It is transmitted mainly by CULEX spp mosquitoes which feed primarily on birds, but it can also be carried by the Asian Tiger mosquito, AEDES albopictus, which feeds mainly on mammals.
The binding of virus particles to receptors on the host cell surface. For enveloped viruses, the virion ligand is usually a surface glycoprotein as is the cellular receptor. For non-enveloped viruses, the virus CAPSID serves as the ligand.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Any of the processes by which cytoplasmic factors influence the differential control of gene action in viruses.
A group of viruses in the PNEUMOVIRUS genus causing respiratory infections in various mammals. Humans and cattle are most affected but infections in goats and sheep have also been reported.
The measurement of infection-blocking titer of ANTISERA by testing a series of dilutions for a given virus-antiserum interaction end-point, which is generally the dilution at which tissue cultures inoculated with the serum-virus mixtures demonstrate cytopathology (CPE) or the dilution at which 50% of test animals injected with serum-virus mixtures show infectivity (ID50) or die (LD50).
Proteins synthesized by HUMAN IMMUNODEFICIENCY VIRUSES such as the HIV-1 and HIV-2.
Agents used in the prophylaxis or therapy of VIRUS DISEASES. Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly.
Viral proteins that are components of the mature assembled VIRUS PARTICLES. They may include nucleocapsid core proteins (gag proteins), enzymes packaged within the virus particle (pol proteins), and membrane components (env proteins). These do not include the proteins encoded in the VIRAL GENOME that are produced in infected cells but which are not packaged in the mature virus particle,i.e. the so called non-structural proteins (VIRAL NONSTRUCTURAL PROTEINS).
The ability of a pathogenic virus to lie dormant within a cell (latent infection). In eukaryotes, subsequent activation and viral replication is thought to be caused by extracellular stimulation of cellular transcription factors. Latency in bacteriophage is maintained by the expression of virally encoded repressors.
Species of the genus LENTIVIRUS, subgenus primate immunodeficiency viruses (IMMUNODEFICIENCY VIRUSES, PRIMATE), that induces acquired immunodeficiency syndrome in monkeys and apes (SAIDS). The genetic organization of SIV is virtually identical to HIV.
The mechanism by which latent viruses, such as genetically transmitted tumor viruses (PROVIRUSES) or PROPHAGES of lysogenic bacteria, are induced to replicate and then released as infectious viruses. It may be effected by various endogenous and exogenous stimuli, including B-cell LIPOPOLYSACCHARIDES, glucocorticoid hormones, halogenated pyrimidines, IONIZING RADIATION, ultraviolet light, and superinfecting viruses.
A strain of Murine leukemia virus (LEUKEMIA VIRUS, MURINE) arising during the propagation of S37 mouse sarcoma, and causing lymphoid leukemia in mice. It also infects rats and newborn hamsters. It is apparently transmitted to embryos in utero and to newborns through mother's milk.
The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.
Visible morphologic changes in cells infected with viruses. It includes shutdown of cellular RNA and protein synthesis, cell fusion, release of lysosomal enzymes, changes in cell membrane permeability, diffuse changes in intracellular structures, presence of viral inclusion bodies, and chromosomal aberrations. It excludes malignant transformation, which is CELL TRANSFORMATION, VIRAL. Viral cytopathogenic effects provide a valuable method for identifying and classifying the infecting viruses.
Viruses that produce tumors.
A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
Proteins found mainly in icosahedral DNA and RNA viruses. They consist of proteins directly associated with the nucleic acid inside the NUCLEOCAPSID.
Group of alpharetroviruses (ALPHARETROVIRUS) producing sarcomata and other tumors in chickens and other fowl and also in pigeons, ducks, and RATS.
Method for measuring viral infectivity and multiplication in CULTURED CELLS. Clear lysed areas or plaques develop as the VIRAL PARTICLES are released from the infected cells during incubation. With some VIRUSES, the cells are killed by a cytopathic effect; with others, the infected cells are not killed but can be detected by their hemadsorptive ability. Sometimes the plaque cells contain VIRAL ANTIGENS which can be measured by IMMUNOFLUORESCENCE.
Membrane glycoproteins from influenza viruses which are involved in hemagglutination, virus attachment, and envelope fusion. Fourteen distinct subtypes of HA glycoproteins and nine of NA glycoproteins have been identified from INFLUENZA A VIRUS; no subtypes have been identified for Influenza B or Influenza C viruses.
A family of RNA viruses causing INFLUENZA and other diseases. There are five recognized genera: INFLUENZAVIRUS A; INFLUENZAVIRUS B; INFLUENZAVIRUS C; ISAVIRUS; and THOGOTOVIRUS.
Infections produced by oncogenic viruses. The infections caused by DNA viruses are less numerous but more diverse than those caused by the RNA oncogenic viruses.
Insertion of viral DNA into host-cell DNA. This includes integration of phage DNA into bacterial DNA; (LYSOGENY); to form a PROPHAGE or integration of retroviral DNA into cellular DNA to form a PROVIRUS.
A genus of FLAVIVIRIDAE causing parenterally-transmitted HEPATITIS C which is associated with transfusions and drug abuse. Hepatitis C virus is the type species.
Family of RNA viruses that infects birds and mammals and encodes the enzyme reverse transcriptase. The family contains seven genera: DELTARETROVIRUS; LENTIVIRUS; RETROVIRUSES TYPE B, MAMMALIAN; ALPHARETROVIRUS; GAMMARETROVIRUS; RETROVIRUSES TYPE D; and SPUMAVIRUS. A key feature of retrovirus biology is the synthesis of a DNA copy of the genome which is integrated into cellular DNA. After integration it is sometimes not expressed but maintained in a latent state (PROVIRUSES).
Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A family of unenveloped RNA viruses with cubic symmetry. The twelve genera include ORTHOREOVIRUS; ORBIVIRUS; COLTIVIRUS; ROTAVIRUS; Aquareovirus, Cypovirus, Phytoreovirus, Fijivirus, Seadornavirus, Idnoreovirus, Mycoreovirus, and Oryzavirus.
A species of RESPIROVIRUS also called hemadsorption virus 2 (HA2), which causes laryngotracheitis in humans, especially children.
Immunoglobulins produced in response to VIRAL ANTIGENS.
A species of ALPHAVIRUS isolated in central, eastern, and southern Africa.
The relationships of groups of organisms as reflected by their genetic makeup.
A broad category of viral proteins that play indirect roles in the biological processes and activities of viruses. Included here are proteins that either regulate the expression of viral genes or are involved in modifying host cell functions. Many of the proteins in this category serve multiple functions.
The type species of RUBULAVIRUS that causes an acute infectious disease in humans, affecting mainly children. Transmission occurs by droplet infection.
The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.
Viruses which produce a mottled appearance of the leaves of plants.
A family of non-enveloped viruses infecting mammals (MASTADENOVIRUS) and birds (AVIADENOVIRUS) or both (ATADENOVIRUS). Infections may be asymptomatic or result in a variety of diseases.
Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen.
Proteins encoded by the GAG GENE of the HUMAN IMMUNODEFICIENCY VIRUS.
A species in the genus HEPATOVIRUS containing one serotype and two strains: HUMAN HEPATITIS A VIRUS and Simian hepatitis A virus causing hepatitis in humans (HEPATITIS A) and primates, respectively.
A genus of the family HERPESVIRIDAE, subfamily ALPHAHERPESVIRINAE, consisting of herpes simplex-like viruses. The type species is HERPESVIRUS 1, HUMAN.
Layers of protein which surround the capsid in animal viruses with tubular nucleocapsids. The envelope consists of an inner layer of lipids and virus specified proteins also called membrane or matrix proteins. The outer layer consists of one or more types of morphological subunits called peplomers which project from the viral envelope; this layer always consists of glycoproteins.
In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.
The type species of SIMPLEXVIRUS causing most forms of non-genital herpes simplex in humans. Primary infection occurs mainly in infants and young children and then the virus becomes latent in the dorsal root ganglion. It then is periodically reactivated throughout life causing mostly benign conditions.
Polyprotein products of a fused portion of retroviral mRNA containing the gag and pol genes. The polyprotein is synthesized only five percent of the time since pol is out of frame with gag, and is generated by ribosomal frameshifting.
A species of POLYOMAVIRUS apparently infecting over 90% of children but not clearly associated with any clinical illness in childhood. The virus remains latent in the body throughout life and can be reactivated under certain circumstances.
Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells.
Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.
A species of POLYOMAVIRUS, originally isolated from the brain of a patient with progressive multifocal leukoencephalopathy. The patient's initials J.C. gave the virus its name. Infection is not accompanied by any apparent illness but serious demyelinating disease can appear later, probably following reactivation of latent virus.
The type species of ALPHARETROVIRUS producing latent or manifest lymphoid leukosis in fowl.
Includes the spectrum of human immunodeficiency virus infections that range from asymptomatic seropositivity, thru AIDS-related complex (ARC), to acquired immunodeficiency syndrome (AIDS).
The type species of ORBIVIRUS causing a serious disease in sheep, especially lambs. It may also infect wild ruminants and other domestic animals.
The interactions between a host and a pathogen, usually resulting in disease.
A sequence of successive nucleotide triplets that are read as CODONS specifying AMINO ACIDS and begin with an INITIATOR CODON and end with a stop codon (CODON, TERMINATOR).
Viruses whose taxonomic relationships have not been established.
An enzyme that synthesizes DNA on an RNA template. It is encoded by the pol gene of retroviruses and by certain retrovirus-like elements. EC
Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.
The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.
Virus diseases caused by the ORTHOMYXOVIRIDAE.
The type species of RESPIROVIRUS in the subfamily PARAMYXOVIRINAE. It is the murine version of HUMAN PARAINFLUENZA VIRUS 1, distinguished by host range.
A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.
The study of the structure, growth, function, genetics, and reproduction of viruses, and VIRUS DISEASES.
Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.
Genus of non-oncogenic retroviruses which establish persistent infections in many animal species but are considered non-pathogenic. Its species have been isolated from primates (including humans), cattle, cats, hamsters, horses, and sea lions. Spumaviruses have a foamy or lace-like appearance and are often accompanied by syncytium formation. SIMIAN FOAMY VIRUS is the type species.
Specific hemagglutinin subtypes encoded by VIRUSES.
An enzyme that catalyzes the hydrolysis of alpha-2,3, alpha-2,6-, and alpha-2,8-glycosidic linkages (at a decreasing rate, respectively) of terminal sialic residues in oligosaccharides, glycoproteins, glycolipids, colominic acid, and synthetic substrate. (From Enzyme Nomenclature, 1992)
The type species of TOBAMOVIRUS which causes mosaic disease of tobacco. Transmission occurs by mechanical inoculation.
Inactivation of viruses by non-immune related techniques. They include extremes of pH, HEAT treatment, ultraviolet radiation, IONIZING RADIATION; DESICCATION; ANTISEPTICS; DISINFECTANTS; organic solvents, and DETERGENTS.
Retroviral proteins, often glycosylated, coded by the envelope (env) gene. They are usually synthesized as protein precursors (POLYPROTEINS) and later cleaved into the final viral envelope glycoproteins by a viral protease.
The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
The type species of LYMPHOCRYPTOVIRUS, subfamily GAMMAHERPESVIRINAE, infecting B-cells in humans. It is thought to be the causative agent of INFECTIOUS MONONUCLEOSIS and is strongly associated with oral hairy leukoplakia (LEUKOPLAKIA, HAIRY;), BURKITT LYMPHOMA; and other malignancies.
Duplex DNA sequences in eukaryotic chromosomes, corresponding to the genome of a virus, that are transmitted from one cell generation to the next without causing lysis of the host. Proviruses are often associated with neoplastic cell transformation and are key features of retrovirus biology.
The type species in the genus NOROVIRUS, first isolated in 1968 from the stools of school children in Norwalk, Ohio, who were suffering from GASTROENTERITIS. The virions are non-enveloped spherical particles containing a single protein. Multiple strains are named after the places where outbreaks have occurred.
A suborder of PRIMATES consisting of six families: CEBIDAE (some New World monkeys), ATELIDAE (some New World monkeys), CERCOPITHECIDAE (Old World monkeys), HYLOBATIDAE (gibbons and siamangs), CALLITRICHINAE (marmosets and tamarins), and HOMINIDAE (humans and great apes).
The type species of the FLAVIVIRUS genus. Principal vector transmission to humans is by AEDES spp. mosquitoes.
Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.
Elements of limited time intervals, contributing to particular results or situations.
A protein-nucleic acid complex which forms part or all of a virion. It consists of a CAPSID plus enclosed nucleic acid. Depending on the virus, the nucleocapsid may correspond to a naked core or be surrounded by a membranous envelope.
Proteins prepared by recombinant DNA technology.
DNA sequences that form the coding region for proteins associated with the viral core in retroviruses. gag is short for group-specific antigen.
The entering of cells by viruses following VIRUS ATTACHMENT. This is achieved by ENDOCYTOSIS, by direct MEMBRANE FUSION of the viral membrane with the CELL MEMBRANE, or by translocation of the whole virus across the cell membrane.
Proteins conjugated with nucleic acids.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
INFLAMMATION of the LIVER in humans caused by HEPATITIS C VIRUS, a single-stranded RNA virus. Its incubation period is 30-90 days. Hepatitis C is transmitted primarily by contaminated blood parenterally, and is often associated with transfusion and intravenous drug abuse. However, in a significant number of cases, the source of hepatitis C infection is unknown.
Proteins, usually glycoproteins, found in the viral envelopes of a variety of viruses. They promote cell membrane fusion and thereby may function in the uptake of the virus by cells.
Pneumovirus infections caused by the RESPIRATORY SYNCYTIAL VIRUSES. Humans and cattle are most affected but infections in goats and sheep have been reported.
Techniques and strategies which include the use of coding sequences and other conventional or radical means to transform or modify cells for the purpose of treating or reversing disease conditions.
A species of ARENAVIRUS, part of the Old World Arenaviruses (ARENAVIRUSES, OLD WORLD), and the etiologic agent of LASSA FEVER. LASSA VIRUS is a common infective agent in humans in West Africa. Its natural host is the multimammate mouse Mastomys natalensis.
The transfer of bacterial DNA by phages from an infected bacterium to another bacterium. This also refers to the transfer of genes into eukaryotic cells by viruses. This naturally occurring process is routinely employed as a GENE TRANSFER TECHNIQUE.
... termini of RNA from vesicular stomatitis virus and its defective interfering particles". Proceedings of the National Academy of ... Through combinatorial studies of viral and bacterial systems, he has identified targets for novel pharmacological studies. ... and rabies virus (RABV), members of the Rhabdoviridae family of viruses, and for Ebola virus and Marburg virus from the broader ... "The origins of defective interfering particles of the negative-strand RNA viruses". Cell. 26 (2): 145-154. doi:10.1016/0092- ...
Alice Huang, 1.[full citation needed] Huang, Alice S.; Baltimore, David (April 1970). "Defective Viral Particles and Viral ... These DIPs will interfere in replication of the virus because they are reproduced at the expense of a standard viral particle. ... Alice Huang's research focused on defective interfering particles (DIPs) which can be utilized to combat viruses. DIPs are ... Pseudotyping is combining a virus or a part of a virus (vector) with a foreign viral envelope protein. Doing this alters their ...
Despite the inability to isolate them, von Magnus discovered defective interfering particles (DIPs) using the "influenza virus ... "incomplete viruses" or "particles" were produced and that these interfered with viral replication. This resulted in a reduction ... ISBN 978-1-4684-0832-4. Manzoni, Tomaz B; López, Carolina B (July 2018). "Defective (interfering) viral genomes re-explored: ... Huang, Alice S.; Baltimore, David (1977). "2. Defective Interfering Animal Viruses". In Fraenkel-Conrat, Heinz; Wagner, Robert ...
Viral hepatitis is the most common type of hepatitis worldwide. Viral hepatitis is caused by five different viruses (hepatitis ... Viral particles have also been found in saliva and breastmilk. However, kissing, sharing utensils, and breastfeeding do not ... Hepatitis D is a defective virus that requires hepatitis B to replicate and is only found with hepatitis B co-infection. In ... The pathway by which hepatic viruses cause viral hepatitis is best understood in the case of hepatitis B and C. The viruses do ...
It is a proxy measurement rather than a measurement of the absolute quantity of particles: viral particles that are defective ... A plaque-forming unit (PFU) is a measure used in virology to describe the number of virus particles capable of forming plaques ... encephalitis virus with a concentration of 1,000 PFU/μL indicates that 1 μL of the solution contains enough virus particles to ... The concept of plaque-forming units of virus is equivalent to the concept of colony-forming units of bacteria. Viruses portal ...
He and Alice together carried out key experiments on defective interfering particles and viral pseudo types. During this work, ... allowing such viruses to turn viral RNA strands into viral DNA strands. The viruses that fall into this category include HIV. ... Baltimore extended this work and examined two RNA tumor viruses, Rauscher murine leukemia virus and Rous sarcoma virus. He went ... and graduate student Martha Stampfer discovered that VSV involved an RNA-dependent RNA polymerase within the virus particle, ...
"A Sensitive Method for Quantification of Vesicular Stomatitis Virus Defective Interfering Particles: Focus Forming Assay" (PDF ... Some such viruses that are commonly recognized include HPV, T-cell Leukemia virus type I, and hepatitis B. Viral oncogenesis ... The retroviruses include T-cell Leukemia virus type I, HIV, and Rous Sarcoma Virus (RSV). The viral gene tax is expressed when ... Human immunodeficiency virus is a viral infection that targets the lymph nodes. HIV binds to the immune CD4 cell and reverse ...
Armstrong, J. A.; Porterfield, J. S.; De Madrid, A. T. (1971). "C-type virus particles in pig kidney cell lines". The Journal ... two defective PERV genomes could give rise to an infectious virus.[40] There are three subgroups of infectious PERVs (PERV-A, ... Endogenous retroviruses are remnants of ancient viral infections, found in the genomes of most, if not all, mammalian species. ... however the virus may become infectious in another species.[21] PERVS were originally discovered as retrovirus particles ...
The latter is true for many unencapsidated dsRNA viruses, which are assumed to be viral, but missing sequence data prevented ... Fungi are frequently infected with two or more unrelated viruses and also with defective dsRNA and/or satellite dsRNA. There ... are viruses that infect fungi. The majority of mycoviruses have double-stranded RNA (dsRNA) genomes and isometric particles, ... The updated 9th ICTV report on virus taxonomy lists over 90 mycovirus species covering 10 viral families, of which 20% were ...
T4 has a burst size of approximately 100-150 viral particles per infected host. Benzer (1955 - 1959) developed a system for ... One noteworthy study used amber mutants defective in the gene encoding the major head protein of phage T4. This experiment ... Nonenveloped viruses lyse the host cell which is characterized by viral proteins attacking the peptidoglycan or membrane. The ... Escherichia virus T4 is a species of bacteriophages that infect Escherichia coli bacteria. It is a double-stranded DNA virus in ...
Virus-Like-Particles (VLPs) of FHV spontaneously form in S. frugiperda cell lines (e.g. Sf21) when RNA2 is expressed from a ... Infection of these organisms by FHV has been demonstrated to have similar characteristics in terms of viral titre, virus ... FHV has provided a model system for the study of the emergence and evolution of defective-interfering RNAs (DI-RNAs). Odegard, ... Flock House virus (FHV) is in the alphanodavirus genus of the Nodaviridae family of viruses. Flock House virus was isolated ...
... genome but retains the sequences necessary for replication and packaging of viral particles in the presence of a helper virus. ... "Utilizing fowlpox virus recombinants to generate defective RNAs of the coronavirus infectious bronchitis virus". The Journal of ... "Presence of an encephalomyocarditis virus internal ribosome entry site sequence in avian infectious bronchitis virus defective ... The Infectious bronchitis virus D-RNA is an RNA element known as defective RNA or D-RNA. This element is thought to be ...
UTR of Tombusvirus defective interfering particles (DI). Defective interfering RNAs are small sub-viral replicons which are non ... Tombus virus defective interfering (DI) RNA region 3 is an important cis-regulatory region identified in the 3' ... Page for Tombus virus defective interfering (DI) RNA region 3 at Rfam v t e. ... Infectious bronchitis virus D-RNA Red clover necrotic mosaic virus translation enhancer elements Ray D, White KA (2003). "An ...
"Immunostimulatory Defective Viral Genomes from Respiratory Syncytial Virus Promote a Strong Innate Antiviral Response during ... In other words, defective and non-defective viruses replicate simultaneously, but when defective particles increase, the amount ... Defective interfering particles (DIPs), also known as defective interfering viruses, are spontaneously generated virus mutants ... Huang AS, Baltimore D (1970). "Defective viral particles and viral disease processes". Nature. 226 (5243): 325-7. doi:10.1038/ ...
Virus-like particles (VLPs) are molecules that closely resemble viruses, but are non-infectious because they contain no viral ... These are defective, immature virions, sometimes containing genetic material, that are generally non-infective due to the lack ... Mohsen MO, Gomes AC, Vogel M, Bachmann MF (July 2018). "Interaction of Viral Capsid-Derived Virus-Like Particles (VLPs) with ... "Ebola Virus-like Particles Prevent Lethal Ebola Virus Infection" (PDF). United States Army Medical Research Institute of ...
... make the host cell continually secrete new virus particles. Released virions are described as free, and, unless defective, are ... Their viral genome will integrate with host DNA and replicate along with it, relatively harmlessly, or may even become ... T7 phage T12 phage Viruses portal Virophage, viruses that infect other viruses Bacterivore CrAssphage DNA viruses Phage ecology ... In the case of the T4 phage, the construction of new virus particles involves the assistance of helper proteins that act ...
... viruses exist in the form of independent particles. These viral particles, also known as virions, consist of two or three parts ... It is, therefore, a defective virus. Although hepatitis delta virus genome may replicate independently once inside a host cell ... I: dsDNA viruses. II: ssDNA viruses. III: dsRNA viruses. IV: (+)ssRNA viruses. V: (−)ssRNA viruses. VI: ssRNA-RT viruses. VII: ... A virus has either a DNA or an RNA genome and is called a DNA virus or an RNA virus, respectively. The vast majority of viruses ...
... make the host cell continually secrete new virus particles. Released virions are described as free, and, unless defective, are ... Of the viral families with DNA genomes, only two have single-stranded genomes. Eight of the viral families with DNA genomes ... In the case of the T4 phage, the construction of new virus particles involves the assistance of helper proteins. The base ... A bacteriophage (/bækˈtɪərioʊfeɪdʒ/), also known informally as a phage (/feɪdʒ/), is a virus that infects and replicates within ...
Each virion contains a full length copy, or defective interfering copies. The viral genome encodes viral structural protein. ... Virus capsid is not enveloped, round with T=3 icosahedral symmetry. The isometric capsid has a diameter of 35-39 nm. Particles ... Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method ... believed to consist of defective interfering particles). Under in vitro conditions virions are inactivated in acid environment ...
... or transported back into the nucleus to bind vRNA and form new viral genome particles (step 5a). Other viral proteins have ... Influenza virus A Influenza A virus* H1N1, H1N2, H2N2, H3N1, H3N2, H3N8, H5N1, H5N2, H5N3, H5N8, H5N9, H7N1, H7N2, H7N3, H7N4, ... Each virion may contain defective interfering copies. In Influenza A (H1N1) PB1-F2 is produced from an alternative reading ... International Committee on Taxonomy of Viruses Index of Viruses - Orthomyxovirus (2006). In: ICTVdB-The Universal Virus ...
Although it is likely that most of these are defective, some may be able to produce infectious viruses so every proviral genome ... Armstrong, J. A.; Porterfield, J. S.; De Madrid, A. T. (1971). "C-type virus particles in pig kidney cell lines". The Journal ... Endogenous retroviruses are remnants of ancient viral infections, found in the genomes of most, if not all, mammalian species. ... however the virus may become infectious in another species. PERVS were originally discovered as retrovirus particles released ...
Defective interfering RNA[edit]. Defective interfering RNA (DI) molecules are RNAs that are produced from the viral genome but ... because ribonucleoprotein particles containing viral genetic material can spread to immediate neighbors through plasmodesmata. ... Tomato bushy stunt virus (TBSV) is a virus that is the type species of the tombusvirus family.[2] It was first reported in ... TBSV is an unenveloped icosahedral virus with a T=3 viral capsid composed of 180 subunits of a single capsid protein. Its ...
... including ones originating from intact infectious viral particles, from defective viral particles as well as free nucleic acid ... For example, the production of viral vaccines, recombinant proteins using viral vectors and viral antigens all require virus ... virus particles) occurring at a known average rate (virus titer) are likely to occur in a fixed space (the amount of virus ... A viral plaque is formed when a virus infects a cell within the fixed cell monolayer. The virus infected cell will lyse and ...
In general, the virus's morphology is ellipsoidal with particles 100-120 nm in diameter, or filamentous with particles 80-100 ... or transported back into the nucleus to bind vRNA and form new viral genome particles (step 5a). Other viral proteins have ... Each virion may contain defective interfering copies. In Influenza A (H1N1) PB1-F2 is produced from an alternative reading ... After the release of new influenza virus, the host cell dies. Orthomyxoviridae viruses are one of two RNA viruses that ...
... viruses exist in the form of independent particles. These viral particles, also known as virions, consist of: (i) the genetic ... It is, therefore, a defective virus. Although hepatitis delta virus genome may replicate independently once inside a host cell ... A virus has either a DNA or an RNA genome and is called a DNA virus or an RNA virus, respectively. The vast majority of viruses ... Plant virus particles or virus-like particles (VLPs) have applications in both biotechnology and nanotechnology. The capsids of ...
"Immunization with a replication-defective herpes simplex virus 2 mutant reduces herpes simplex virus 1 infection and prevents ... Inactivated vaccines, which consist of intact viral particles, dramatically increase the repertoire of viral antigens that ... The enzyme disables a gene responsible for producing a protein involved in the maturation and release of viral particles in an ... Results showed up to a 75% reduction in viral load and a weak reduction in viral shedding by 14%. These results were achieved ...
The term virion (plural virions), which dates from 1959, is also used to refer to a single viral particle that is released from ... It is, therefore, a defective virus. Although hepatitis delta virus genome may replicate independently once inside a host cell ... Plant virus particles or virus-like particles (VLPs) have applications in both biotechnology and nanotechnology. The capsids of ... A virus has either a DNA or an RNA genome and is called a DNA virus or an RNA virus, respectively. The vast majority of viruses ...
Defective interfering particles (RNA) Defective interfering particles (DNA) Viruses portal Glossary of scientific naming ... Viruses with a DNA genome, except for the DNA reverse transcribing viruses, are members of three of the four recognized viral ... and foot-and-mouth virus), SARS virus, hepatitis C virus, yellow fever virus, and rubella virus. Group V: viruses possess ... interfering particles are defective viruses that have lost their ability to replicate except in the presence of a helper virus ...
Some cultivars have also shown long, flexuous, rod-shaped, virus-like particles (LFPs) in tissues showing signs of necrosis. ... Fig mosaic disease (FMD) was first described and suspected to be of viral origin in 1933 by Ira J. Condit and W.T.Horne. It was ... Perhaps this is because they are truncated or defective, but the functions of the proteins they encode is still undetermined. ... is common to all viruses of genus Emaravirus and codes for the virus's 264 kDa RNA-dependent RNA polymerase (RdRp), which has ...
Each virion contains a full length copy, or defective interfering copies. The viral genome encodes viral structural protein. ... Virions consist of 1 viral structural protein (major species), or 2 Viral structural proteins (detected in Norwalk virus, ... Transmission routes are air borne particles. The molecular mass (Mr) of virions is 15 x 106. Virions have a buoyant density in ... Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method ...
In segmented RNA viruses, "mating" can occur when a host cell is infected by at least two virus particles. If these viruses ... Some of the viruses evolved into DNA viruses to protect their genes from attack. Through the process of viral infection into ... Further information: Viral eukaryogenesis. Patrick Forterre has been working on a novel hypothesis, called "three viruses, ... they uncovered evidence that a simple DNA virus had acquired a gene from a completely unrelated RNA-based virus. Virologist ...
Vesicular stomatitis virus is believed to be taken up by the autophagosome from the cytosol and translocated to the endosomes ... It often occurs to defective mitochondria following damage or stress. Mitophagy promotes turnover of mitochondria and prevents ... In microbiology, xenophagy is the autophagic degradation of infectious particles. Cellular autophagic machinery also play an ... these findings have not been examined in non-viral systems. ... A subset of viruses and bacteria subvert the autophagic pathway ...
... as recognized by the presence of giant pronormoblasts with viral particles and inclusion bodies, thus temporarily depleting the ... The inability to carry out protein synthesis means that no virus can evolve to target mammalian red blood cells.[43] However, ... thus removing old and defective cells and continually purging the blood. This process is termed eryptosis, red blood cell ... Red blood cells are thus much more common than the other blood particles: there are about 4,000-11,000 white blood cells and ...
Many viruses encode proteins that can inhibit apoptosis.[103] Several viruses encode viral homologs of Bcl-2. These homologs ... Released viral particles and proteins present in extracellular fluid are able to induce apoptosis in nearby "bystander" T ... Defective pathways[edit]. The many different types of apoptotic pathways contain a multitude of different biochemical ... they were able to suppress viral budding. By suppressing viral budding, the researchers were able to trap the HIV virus in the ...
1996) Maternal viral load, zidovudine treatment, and the risk of transmission of human immunodeficiency virus type 1 from ... Monti-Bragadin C, Ulrich K. (1972) Rescue of the genome of the defective murine sarcoma virus from a non-producer hamster tumor ... 1973) Purification and partial differentiation of the particles of murine sarcoma virus (M. MSV) according to their ... 1976) Murine sarcoma virus defectiveness: serological detection of only helper virus reverse transcriptase in sarcoma virus ...
In 1950, Renato Dulbecco now at Caltech with Delbrück, worked out a procedure for assaying animal virus particles by their ... HERSHEY AD, CHASE M. "Independent functions of viral protein and nucleic acid in growth of bacteriophage". J Gen Physiol. 1952 ... One noteworthy study was performed by Sydney Brenner and collaborators using amber mutants defective in the gene encoding the ... Luria S. E., Delbrück M. "Mutations of Bacteria from Virus Sensitivity to Virus Resistance". Genetics. 1943 Nov;28(6):491-511. ...
Beside interacting with the cell membrane, lactoferrin also directly binds to viral particles, such as the hepatitis viruses. ... "A novel host defense system of airways is defective in cystic fibrosis". Am. J. Respir. Crit. Care Med. 175 (2): 174-83. doi: ... human respiratory syncytial virus, murine leukemia viruses and Mayaro virus. The most studied mechanism of antiviral activity ... Lactoferrin binds to the same lipoproteins thereby repelling the virus particles. Iron-free apolactoferrin is more efficient in ...
In this way, they are similar to viruses. Various viruses and TEs also share features in their genome structures and ... Defective interfering particle. *Plasmid. *Cosmid. *Phagemid. *Fosmid. *Transpoviron. *Transposable element *Retroposon. * ... Bacteria may undergo high rates of gene deletion as part of a mechanism to remove TEs and viruses from their genomes, while ... Villarreal L (2005). Viruses and the Evolution of Life. Washington: ASM Press.. ...
5.2.2 Israeli acute paralysis virus. *5.2.3 Nosema. *5.3 Viral and fungal combination ... The defective rectum indicates nutritional disruption or water imbalance, whereas rectal enteroliths suggest a malfunction of ... According to the study, "Experimental results show that the environmental release of particles containing neonicotinoids can ... due in part to the viruses it carries, including deformed wing virus and acute bee paralysis virus, which have both been ...
"Simian virus 40 DNA sequences in DNA of healthy adult mice derived from preimplantation blastocysts injected with viral DNA". ... Genetic engineering could potentially fix severe genetic disorders in humans by replacing the defective gene with a functioning ... where particles of gold or tungsten are coated with DNA and then shot into young plant cells,[61] and electroporation, which ... Paul Berg created the first recombinant DNA molecules by combining DNA from the monkey virus SV40 with that of the lambda virus ...
Many viruses encode proteins that can inhibit apoptosis.[94] Several viruses encode viral homologs of Bcl-2. These homologs can ... Released viral particles and proteins present in extracellular fluid are able to induce apoptosis in nearby "bystander" T ... Defective pathways[edit]. The many different types of apoptotic pathways contain a multitude of different biochemical ... April 2010). "Apoptosis induced by Oropouche virus infection in HeLa cells is dependent on virus protein expression". Virus Res ...
In acutely transforming viruses, the viral particles carry a gene that encodes for an overactive oncogene called viral-oncogene ... Mutation rates strongly increase in cells defective in DNA mismatch repair[21][22] or in homologous recombinational repair (HRR ... In contrast, in slowly transforming viruses, the virus genome is inserted, especially as viral genome insertion is obligatory ... Viral[edit]. Main article: Oncovirus. Furthermore, many cancers originate from a viral infection; this is especially true in ...
Each nucleoid particle may contain more than 10 copies of the plastid DNA. The proplastid contains a single nucleoid located in ... Synthetic virus *Viral vector. *Helper dependent virus. *?Nanobacterium. *?Nanobe. *Cancer cell *HeLa ...
The viral neuraminidases are frequently used as antigenic determinants found on the surface of the influenza virus. Some ... There are two major proteins on the surface of influenza virus particles. One is the lectin haemagglutinin protein with three ... "Characterization of temperature sensitive influenza virus mutants defective in neuraminidase". Virology. 61 (2): 397-410. doi: ... "Influenza type A virus neuraminidase does not play a role in viral entry, replication, assembly, or budding". Journal of ...
Beside interacting with the cell membrane, lactoferrin also directly binds to viral particles, such as the hepatitis viruses.[ ... "A novel host defense system of airways is defective in cystic fibrosis". American Journal of Respiratory and Critical Care ... and Mayaro virus.[52]. The most studied mechanism of antiviral activity of lactoferrin is its diversion of virus particles from ... Lactoferrin also suppresses virus replication after the virus penetrated into the cell.[41][48] Such an indirect antiviral ...
In asymptomatic infections, the amoeba lives by eating and digesting bacteria and food particles in the gut, a part of the ... Joel Connolly of the Chicago Bureau of Sanitary Engineering brought the outbreak to an end when he found that defective ... and perhaps associated bacteria and viruses. ... In fact, most traveler's diarrhea is bacterial or viral in ...
... as small as the largest viruses.[33] Some bacteria may be even smaller, but these ultramicrobacteria are not well-studied.[34] ... "Collective bacterial dynamics revealed using a three-dimensional population-scale defocused particle tracking technique" ... which allows them to block virus replication through a form of RNA interference.[125][126] The third method of gene transfer is ... "CRISPR provides acquired resistance against viruses in prokaryotes". Science. 315 (5819): 1709-12. Bibcode:2007Sci...315.1709B ...
... which causes the host cell to generate viral proteins that reassemble into new viral particles. In HIV, subsequent to this, the ... "Tentative identification of RNA-dependent RNA polymerases of dsRNA viruses and their relationship to positive strand RNA viral ... This is because the positive-sense strand contains the information needed to translate the viral proteins for viral replication ... Some viruses (such as HIV, the cause of AIDS), have the ability to transcribe RNA into DNA. HIV has an RNA genome that is ...
The drop in HIV virus levels may be due to a lack of target CD4+ T cells in which they replicate, or measles virus may ... Many particles in disease fuel are so tiny they are able to penetrate deep into the lungs when inhaled. Importantly, diesel ... More people died of the so-called Spanish flu (caused by the H1N1 viral strain) pandemic in the single year of 1918 than during ... The vaccine was created using a replication-defective version of Ad5 as a carrier, or delivery vector, for three synthetically ...
... of a uniformly dispersed assembly of strongly interacting particles in suspension requires total control over particle-particle ... The structure of foraminifera (mainly chalk) and viruses (protein, capsid), the wax crystals covering a lotus or nasturtium ... Such defective polycrystalline colloidal structures would appear to be the basic elements of sub-micrometer colloidal materials ... He published a book in 1914.[45] He used an ultramicroscope that employs a dark field method for seeing particles with sizes ...
... of vesicular stomatitis virus are conditionally defective particles that interfere with and are rescued by wild-type virus". ... The key to effective inactivation depended upon a color test developed by Youngner, which allowed formalin induced viral ... "one live virus particle in 100 million doses of vaccine." By 1954, the first virus trials had immunized 800,000 children ... His team studied the mechanisms of these infections, and also infections of vesicular stomatitis virus, sendai virus, and ...
1965). "Adenovirus-Associated Defective Virus Particles". Science. 149 (3685): 754-6. Bibcode:1965Sci...149..754A. doi:10.1126/ ... A helper dependent virus, also termed a gutless virus, is a synthetic viral vector dependent on the assistance of a helper ... Hepatitis D virus (HDV) is an example of a replication defective, helper dependent ssRNA virus because it requires Hepatitis B ... Naturally-occurring satellite viruses are also helper virus dependent, and can sometimes be modified to become viral vectors. ...
Structure of the intracellular defective viral RNAs of defective interfering particles of mouse hepatitis virus. / Makino, S.; ... title = "Structure of the intracellular defective viral RNAs of defective interfering particles of mouse hepatitis virus", ... T1 - Structure of the intracellular defective viral RNAs of defective interfering particles of mouse hepatitis virus ... Structure of the intracellular defective viral RNAs of defective interfering particles of mouse hepatitis virus. ...
9. Interesting microbiology #1 - Defective interfering particles. a. Influenza viruses have interesting microbiology. They have ... These Dis require coinfection with other viruses to proliferate. Since viral resources are being used to produce Dis, less ... Thus, some incomplete virions are produced, defective interfering particles (Dis). DIs are virions without the full genome ... a. Influenza viruses can infect many different animals including birds and pigs, which can serve as vectors and reservoirs, ...
RNQ Synthesis by Defective Interfering Vesicular Stomatitis Virus Particles 11. Rhabdovirus Defective Particles: Origin and ... Rhabdovirus Assembly and Intracellular Processing of Viral Components 7. Rhabdovirus Genetics 8. Gene Assignment and ... Complementation Group 9. Homologous Interference by Defective Virus Particles 10. ... Ribosome Recognition and Translation of Vesicular Stomatitis Virus Messenger RNA 4. Gene Order 5. RNA Replication 6. ...
Defective interfering viral particles in acute dengue infections. PLoS One 6:e19447. doi:10.1371/journal.pone.0019447. ... virus (3, 4). Influenza virus defective interfering particles have been observed during in vitro serial passages in cell ... Influenza virus DI particles are generated during multiple passages of infectious viruses in the host cell where the defective ... this defective virus was also able to protect against other unrelated heterologous viruses like influenza B virus (33). These ...
Hepatitis C virus (HCV), which has proven to be the major etiologic agent of blood-borne NANBH, was discovered by Applicant. ... Nucleic acids were extracted from particles isolated from high titer chimpanzee HCV plasma as follows. First, viral particles ... Defective viruses have been known to occur in RNA viruses. By using PCR technology it is possible to design primers to amplify ... 1987)), Yellow Fever Virus (Rice et al. (1985)), Dengue Type 2 Virus (Hahn et al. (1988)), Dengue Type 4 Virus (Mackow (1987 ...
... and the University of Haifa are engineering a new antiviral agent against viruses such as polio. ... Defective versions of viruses naturally occur because of errors during viral replication; they have been observed, for example ... Mathematical and computational modeling of virus and defective particles competition at single cell, tissue, organ and host ... DIPs can compete and co-evolve along with viruses. Like DIPs, vaccines also use a defective version of viruses, but as a ...
1. A fragment or component of a virus; a viral particle.. 2. Defective virus. ...
Inhibition of Nipah Virus by Defective Interfering Particlesexternal icon. J Infect Dis. 2020 Feb 28:jiz564. ... Stable Occupancy of the Crimean-Congo Hemorrhagic Fever Virus-Encoded Deubiquitinase Blocks Viral Infectionexternal icon. mBio ... Viruses. 2019 Mar 2;11(3):214.. Malvy D, McElroy AK, de Clerck H, et al. Ebola virus diseaseexternal icon. Lancet. 2019 Mar 2; ... Single-dose Replicon Particle Vaccine Provides Complete Protection Against Crimean-Congo Hemorrhagic Fever Virus in Mice ...
Viral and host proteins exposed on the envelope of HCV virions. (A) Representative images of tag-HCV particles purified on 2% ( ... 1996) Visualization of hepatitis C virions and putative defective interfering particles isolated from low-density lipoproteins ... Ten-nanometer gold particles (Aurion Gold Sol, EMS) were added to the virus suspension to serve as fiduciary markers for ... E and F) Two sections through the 3D tomogram of an HCV particle showing striations in the envelope (arrows) and viral membrane ...
The virus was concentrated and purified to obtain … ... cells infected with mouse hepatitis virus strain A59 (MHV-A59 ... We have determined the kinetics of virus production and virus-specific RNA synthesis in Sac(−) ... RNA1 comigrated with the viral genome. Artifacts caused by defective interfering particles or breakdown of RNA were excluded. ... Release of virus into the culture medium started 4 hr after infection (pi) and was complete at 10 hr pi. Synthesis of virus- ...
3.3.4 Viral Gene Deletions. 3.3.5 Proteolytic Processing of Virus Particles in Tumor Microenvironment. 4. Cancer Immunotherapy ... 3.2 Efficacy Routes Followed by Oncogenic Viruses. 3.3 Mechanism of Tumor Specificity. 3.3.1 Defective Anti-Viral Responses. ... 4.2 Oncolytic Viruses as Cancer Vaccines. 5. Varieties of Viruses Casted as Oncolytic Viruses. 5.1 Oncolytic Wild Type Viruses ... 9.2 Major Challenges Faced by Oncolytic Virus. 10. Future Aspects of Oncolytic Viral Therapy. 11. Global Oncolytic Virus ...
In vitro, virus-free T particles at extremely high multiplicities depress cellular RNA and protein synthesis and kill BHK21 ... When pure T particles are injected intracerebrally along with large doses of infectious virus, they convert an otherwise ... Intracerebral injection of virus-free T particles alone is apparently innocuous to mice and stimulates immunity to massive ... This profound prophylactic effect of defective T particles is due to homologous autointerference since it is serotype-specific ...
... and polio virus these particles were termed "defective interfering particles" (42). Such particles were found to be ... In virus-infected cells, EVs incorporate fragments of the viral genome and viral (glyco)proteins. Moreover, virus infections ... Such infection-induced EVs and the so-called defective viruses and virus-like particles are intermediate entities, and the ... Defective viruses are also formed but are noninfectious because of the lack of essential viral components. Whereas specific ...
Those are the main properties that make viruses highly attractive gene-delivery vehicles (or vectors). ... Viruses have evolved by borrowing and modifying cellular genes to become extremely efficient at nucleic acid delivery to ... is the poxviral/retroviral chimeric construct that allows cytoplasmic production of transducing defective retroviral particles. ... non-viral means are also increasingly researched. A plethora of such non-viral systems incorporate parts of viral vectors in ...
... termini of RNA from vesicular stomatitis virus and its defective interfering particles". Proceedings of the National Academy of ... Through combinatorial studies of viral and bacterial systems, he has identified targets for novel pharmacological studies. ... and rabies virus (RABV), members of the Rhabdoviridae family of viruses, and for Ebola virus and Marburg virus from the broader ... "The origins of defective interfering particles of the negative-strand RNA viruses". Cell. 26 (2): 145-154. doi:10.1016/0092- ...
Do captured viral genes make human pregnancies possible? by Science News; Science and technology, general Bacteriophages ... Genetic aspects Biologists Research Pregnancy proteins Viral genetics ... The particles turned out to be retroviruses, a viral family that includes the AIDS virus. Like other viruses, retroviruses must ... Even if a person has a defective ERV-3 envelope gene, he says, "there might be a backup system. There might be multiple ...
2011 Defective Interfering Viral Particles in Acute Dengue Infections. PLoS One 6(4): e19447. doi:10.1371/journal.pone.0019447 ... viral) replication of a host-virus or virus-virus recombination event. The probability of sequencing the same original ... Detection of chimeric reads resulting from either host-virus or virus-virus recombination used an approach previously developed ... 2012 Endogenous viruses: insights into viral evolution and impact on host biology. Nat. Rev. Genet. 13(4): 283-296. doi:10.1038 ...
Defective interfering viral particles in acute dengue infections. PLoS One 6:e19447 doi:10.1371/journal.pone.0019447 [PMC free ... Dengue virus envelope glycoprotein structure: new insight into its interactions during viral entry. Proc. Natl. Acad. Sci. U. S ... Viral diversity at the intrahost-interhost interface. To evaluate potential bottlenecks that occur during events such as virus ... Virus Res. 72:1-76 [PubMed]. 69. Vaughn DW, et al. 2000. Dengue viremia titer, antibody response pattern, and virus serotype ...
Over the past forty years, vesicular stomatitis virus (VSV), closely related to rabies virus, has served as a paradigm to study ... Over the past forty years, vesicular stomatitis virus (VSV), closely related to rabies virus, has served as a paradigm to study ... Elucidation of their unique strategies to replicate in eukaryotic cells is crucial to aid in developing anti-NNS RNA viral ... PRNTase or PRNTase-like domains are evolutionally conserved among L proteins of all known NNS RNA viruses and their related ...
Properties of avian retrovirus particles defective in viral protease. J. Virol. 64:5076-5092. [PMC free article] [PubMed] ... Murine leukemia virus nucleocapsid mutant particles lacking viral RNA encapsidate ribosomes. J. Virol. 76:11405-11413. [PMC ... This conversion to an infectious particle is brought about by the cleavage of viral proteins by the virus-encoded protease (PR ... All site 3 mutants were somewhat defective with respect to virus production; culture fluids of S3R particles (i.e., the mutant ...
A remarkable homology of the RABV L protein to a counterpart in vesicular stomatitis virus, a well-characterized rhabdovirus, ... Rabies virus (RABV) is a causative agent of a fatal neurological disease in humans and animals. The large (L) protein of RABV ... Viral proteins required for the in vitro replication of vesicular stomatitis virus defective interfering particle genome RNA. ... Chandipura virus (GU212856), Cocal virus (EU373657), Isfahan virus (AJ810084), Jurona virus (KM204996†), Malpais Spring virus ( ...
Adenoassociated viral systems. Single-stranded AAV are replication-defective viruses. They integrate the host genome (long term ... Therefore, the lentiviral particles generated are replication-incompetent. Adenoviral systems. Adenoviruses are naked viruses ( ... Viral strategy for DNA/RNA delivery. The incredible efficiency of viruses in infecting (entering) a cell was meant to provoke ... The most widely used are Adeno-Assotiated Viruses (AAV) for in vivo expression of foreign sequences and lentiviral particles, ...
Alice Huang, 1.[full citation needed] Huang, Alice S.; Baltimore, David (April 1970). "Defective Viral Particles and Viral ... These DIPs will interfere in replication of the virus because they are reproduced at the expense of a standard viral particle. ... Alice Huangs research focused on defective interfering particles (DIPs) which can be utilized to combat viruses. DIPs are ... Pseudotyping is combining a virus or a part of a virus (vector) with a foreign viral envelope protein. Doing this alters their ...
Likewise, the viral proteins coded in the defective proviruses may form extracellular virus-like particles and may trigger ... Defective HIV-1 proviruses produce viral proteins Proc Natl Acad Sci U S A. 2020 Feb 18;117(7):3704-3710. doi: 10.1073/pnas. ... As these defective proviruses are unable to encode intact and replication-competent viruses, they have long been thought of as ... Contrary to this notion, we have recently demonstrated that these defective proviruses are not silent, are capable of ...
... the deleterious effect of the injection of a low concentration of the purified virus on human embryonic brain tumors induced in ... Brazilian researchers at the Center for Human Genome and Stem Cell Studies at the University of São Paulo have put the virus to ... The results show that these new viral particles are defective, which would prevent uncontrolled virus spreading into the ... And even lower amounts of virus, of one viral particle per ten cells, inhibited the growth of CNS tumor cells. ...
Viruses have been used as transsynaptic tracers, allowing one to map the inputs and outputs of neuronal populations, due to ... Defective viral particles and viral disease processes. Nature 226:325‐327. doi: 10.1038/226325a0. ... Vesicular stomatitis virus with the rabies virus glycoprotein directs retrograde transsynaptic transport among neurons in vivo ... Two retroviral entry pathways distinguished by lipid raft association of the viral receptor and differences in viral ...
A system for production of defective interfering particles in the absence of infectious influenza A virus.. *Read more about A ... Identification of Broad-Spectrum Antiviral Compounds by Targeting Viral Entry. *Read more about Identification of Broad- ... system for production of defective interfering particles in the absence of infectious influenza A virus. ... An avian influenza virus A(H7N9) reassortant that recently emerged in the United States with low pathogenic phenotype does not ...
... the replication defective virus retains the sequences of its genome which are necessary for encapsidating the viral particles. ... Defective viruses, which entirely or almost entirely lack viral genes, are preferred. Defective virus is not infective after ... DNA viral vectors include an attenuated or defective DNA virus, such as but not limited to herpes simplex virus (HSV), ... Viral vectors, such as lentiviruses, retroviruses, herpes viruses, adenoviruses, adeno-associated viruses, vaccinia virus, ...
... the viral genome and harbor deletions of various sizes resulting in the generation of replication incompatible viral particles ... Influenza A virus (IAV) defective RNAs are generated as byproducts of error-prone viral RNA replication. They are commonly ... thereby reducing viral replication of IFN-sensitive viruses such as IAV or vesicular stomatitis virus. This induction of IFN is ... Evidence for a Novel Mechanism of Influenza Virus-Induced Type I Interferon Expression by a Defective RNA-Encoded Protein.. [ ...
MA also plays a role in the incorporation of the viral envelope (Env) glycoproteins and can influence particle infectivity post ... Despite the defect in virus production in these cells, release of the 29KE/31KE mutant is not significantly reduced in primary ... leading to particle assembly in a multivesicular body compartment and defective release of cell-free particles in HeLa and 293T ... Our findings elucidate the mechanism whereby an MA mutant defective in PI(4,5)P2 binding can be rescued and highlight the ...
  • Using affinity grids, previously described to isolate proteins and macromolecular complexes for single-particle EM, we were able to purify enveloped particles directly from cell culture media. (
  • In addition to apolipoprotein (apo)E, HCV particles also incorporate apoB and apoA-I. In general, host apolipoproteins were more readily accessible to antibody labeling than HCV glycoproteins, suggesting either lower abundance or masking by host proteins. (
  • Moreover, EVs generated by virus-infected cells can incorporate viral proteins and fragments of viral RNA, being thus indistinguishable from defective (noninfectious) retroviruses. (
  • EVs, depending on the proteins and genetic material incorporated in them, play a significant role in viral infection, both facilitating and suppressing it. (
  • Such EVs contain viral proteins and parts of viral genetic material. (
  • At least two viral genes captured by the human genome millions of years ago encode proteins that, according to new experiments, may guide the development of the human placenta. (
  • These studies provided insights into how NNS RNA viruses synthesize 5′-capped mRNAs using their RNA-dependent RNA polymerase L proteins equipped with an unconventional mRNA capping enzyme, namely GDP polyribonucleotidyltransferase (PRNTase), domain. (
  • PRNTase or PRNTase-like domains are evolutionally conserved among L proteins of all known NNS RNA viruses and their related viruses belonging to Jingchuvirales , a newly established order, in the class Monjiviricetes , suggesting that they may have evolved from a common ancestor that acquired the unique capping system to replicate in a primitive eukaryotic host. (
  • DIPs are composed of viral structural proteins and sets of DNA or RNA which are incomplete. (
  • In murine leukemia virus (MLV) maturation, Gag is cleaved at three sites, resulting in formation of the matrix (MA), p12, capsid (CA), and nucleocapsid (NC) proteins. (
  • This conversion to an infectious particle is brought about by the cleavage of viral proteins by the virus-encoded protease (PR). (
  • Thus, concerted cleavage of each of the Gag proteins in a virion at three sites induces multiple changes in the particle. (
  • In the present study, by an approach of combining serial dilutions of CD4 + T cells and T cell-cloning technologies, we are able to demonstrate that defective proviruses that persist in HIV-infected individuals during suppressive cART are translationally competent and produce the HIV-1 Gag and Nef proteins. (
  • Likewise, the viral proteins coded in the defective proviruses may form extracellular virus-like particles and may trigger immune responses. (
  • The persistent production of HIV-1 proteins in the absence of viral replication helps explain persistent immune activation despite HIV-1 levels below detection, and also presents new challenges to HIV-1 eradication. (
  • This induction of IFN is completely independent of the defective RNA itself that usually serves as pathogen-associated pattern and thus does not require the cytoplasmic sensor RIG-I. These data suggest that not only defective RNAs, but also some defective RNA-encoded proteins can act immunostimulatory. (
  • Gammaherpesviruses encode proteins with homology to the cellular purine metabolic enzyme formyl-glycinamide-phosphoribosyl-amidotransferase (FGARAT), but the role of these viral FGARATs (vFGARATs) in the pathogenesis of a natural host has not been investigated. (
  • In this paper, we will review the interaction of the lentiviral Vif proteins with the APOBEC3 proteins, with an emphasis on sheep APOBEC3 and maedi-visna virus (MVV) Vif. (
  • In contrast to all other human endogenous retroviruses, some HERV-K proviruses have maintained open reading frames for all viral proteins. (
  • Viral proteins were shown to be expressed in primary melanomas, metastases, and melanoma cell lines by immunohistochemistry, immunofluorescence, and Western blot analyses using specific antisera. (
  • The human endogenous retrovirus K family (HERV-K) consists of 30 to 50 proviruses and is to date the only known human endogenous provirus that has retained open reading frames for all viral proteins ( 2 , 3 ). (
  • Although the full-length mRNA of HERV-K is expressed in many tissues ( 10 ), expression of viral proteins and particle production had, until recently, only been shown for teratocarcinomas ( 11 , 12 ) when enhanced expression was also shown for melanomas ( 13 ). (
  • For the first time, we show expression of viral proteins (including the transmembrane envelope protein) in melanomas using immunohistochemistry and a newly developed HERV-K-specific antiserum and the presence of HERV-K-specific antibodies in patients with melanomas. (
  • Human RNA polymerase II mediates transcription of cccDNA, generating pregenomic RNA (pgRNA) and mRNAs for translation of viral proteins ( 3 ). (
  • A retrovirus‐based gene transfer system consists of two components: the transfer vector, which harbours a foreign gene linked to elements needed for retroviral replication, and the packaging constructs, which supply the necessary retroviral proteins for transfer of the vector from a producer cell through a single round of viral replication. (
  • Four different MLV vector designs are shown: (a) Transfer vector derived by simple replacement of the coding regions of the viral proteins by the coding region of a gene‐of‐interest (GOI). (
  • HSV-1 particles are composed of approximately 40 different virus-encoded structural proteins. (
  • When a cell contains two proviruses, progeny may be found that possess the genome of one but the structural proteins of either or both viruses present. (
  • Conversely, the RNA may be viral but at least some of the proteins may be cellular. (
  • It is generally thought that the Ag processing pathways for endogenously synthesized proteins are the same for allo and viral Ag processing. (
  • We show that the rate of transport of individual endogenous proteins through the organelles of the secretory pathway is also impaired, but only by roughly 50%, suggesting that the defect in this cell line affects the transport of particles to a greater extent than the transport of individual proteins. (
  • In co-infections with wild type viruses DI particles show a replication advantage because they are more efficient at replicating their shorter genome, and compete with wild type virus for essential replication proteins. (
  • The precursor is the p55 myristoylated protein, which is processed to p17 (MAtrix), p24 (CApsid), p7 (NucleoCapsid), and p6 proteins, by the viral protease. (
  • When cells coexpressing all five VSV proteins were superinfected with DI particles, which because of their defectiveness are unable to express any viral proteins or to replicate, DI particle replication, assembly, and budding were observed and infectious DI particles were released into the culture fluids. (
  • The successful replication, assembly, and budding of DI particles from cells expressing all five VSV proteins from cloned cDNAs provide a powerful approach for detailed structure-function analysis of the VSV gene products in each step of the replicative cycle of the virus. (
  • We show here that replication of defective interfering (DI) particle RNA in HEK293 cells stably expressing vesicular stomatitis virus (VSV) replication proteins potently activates interferon (IFN) and IFN signaling pathways through upregulation of IFN- promoter, IFN-stimulated response element (ISRE) promoter, and NF-κB promoter activities. (
  • Replication of DI particle RNA, not mere expression of the viral replication proteins, was found to be critical for induction of IFN and IFN signaling. (
  • The identification of host factors that interact with viral proteins, bind to the viral genome and orchestrate essential steps in the virus life cycle can suggest targets for antiviral drugs. (
  • Although there are several methods currently available to detect and quantitate viral genes, messages, and proteins during the course of infection, none is ideal. (
  • Several of these strategies rely on an array of virally encoded accessory proteins, including Vif, Vpr, Vpu, and Nef, which collectively appear to manipulate host cell biology as a means to ensure a favorable cellular state for viral replication, transmission, dissemination, and immune evasion. (
  • 1 Vpr (Viral protein R), one of these accessory proteins, is a 96-amino acid protein that is expressed at the late stage of the virus life cycle but is present during the early steps of infection because it is packaged into viral particles via an interaction with the p6 domain of Gag. (
  • 23 , 24 Human NKG2D ligands consist of 2 classes of MHC-I-like molecules: MHC-1-related chains (MIC) and human cytomegalovirus UL16 binding proteins (ULBP), which are generally poorly expressed by normal cells and up-regulated on virus-infected, tumor, and stressed cells. (
  • These trVLPs can continuously infect cells expressing the Ebola virus proteins responsible for genome replication and transcription, allowing us to safely model multiple infectious cycles under biosafety level 2 conditions. (
  • Host proteins are incorporated inside human immunodeficiency virus type 1 (HIV-1) virions during assembly and can either positively or negatively regulate HIV-1 infection. (
  • Because the HIV-1 genome only encodes a limited number of viral proteins, HIV-1 must take advantage of multiple functions of host proteins in order to successfully replicate. (
  • Therefore, one way to elucidate the viral replication capacity gained by the packaging of host proteins is to directly analyze the host proteins inside the virions. (
  • The human plasma proteome is likely to contain most, if not all, human proteins, as well as proteins derived from some viruses, bacteria, and fungi. (
  • Influenza virus defective interfering (DI) particles are naturally occurring noninfectious virions typically generated during in vitro serial passages in cell culture of the virus at a high multiplicity of infection. (
  • Hepatitis C virus (HCV) is an important human pathogen that infects the liver and establishes chronic infection in the majority of cases, leading to cirrhosis and hepatocellular carcinoma (HCC) over the course of many years. (
  • Release of virus into the culture medium started 4 hr after infection (pi) and was complete at 10 hr pi. (
  • Prophylaxis and immunization in mice by use of virus-free defective T particles to protect against intracerebral infection by vesicular stomatitis virus. (
  • Deciphering the mechanisms of EV-cell interactions may facilitate the design of EVs that inhibit viral infection and can be used as vehicles for targeted drug delivery. (
  • The underlying mechanism is in the replicative nature of the viruses - the vectors replicate inside the desired cell, mimic an authentic viral infection and result in the stimulation of innate anti-viral reactions in the antigen-expressing cell. (
  • Our data illustrate the value of high-coverage genome-wide analysis of intrahost diversity for high-resolution mapping of the relationship between intrahost diversity and clinical, epidemiological, and virological parameters of viral infection. (
  • Nearly three billion people worldwide are at risk for infection with dengue virus (DENV), a Flavivirus transmitted by the mosquitoes Aedes aegypti and A. albopictus (for reviews, see references 24 and 25 ). (
  • In addition, rabies-like diseases are known to occur in humans by infection with other lyssaviruses, such as Duvenhage virus, European bat lyssaviruses 1 and 2, Australian bat lyssavirus, Mokola virus, and Irkut virus, although in rare cases [ 3 , 7 ]. (
  • The most widely used are Adeno-Assotiated Viruses (AAV) for in vivo expression of foreign sequences and lentiviral particles, showing a high efficiency for in vitro purposes (near 100% infection). (
  • For the purpose of finding a way around the banned importation of exogenous sequences inside a cell, genetic engineering is now able to remove harmful traits of a virus, impairing its self-replication (infection without propagation). (
  • Contrary to this notion, we have recently demonstrated that these defective proviruses are not silent, are capable of transcribing novel unspliced forms of HIV-RNA transcripts with competent open reading frames (ORFs), and can be found in the peripheral blood CD4 + T cells of patients at all stages of HIV-1 infection. (
  • A study published in the journal Cancer Research , of the American Association for Cancer Research, reveals the therapeutic side of the Zika virus, which in 2015 made global public health authorities wary when the link between the infection of the virus during gestation and the birth of children with microcephaly was established. (
  • The researchers also tested in vitro the functionality of viruses formed in tumor cells after infection. (
  • Viral FGARAT ORF75A promotes early events in lytic infection and gammaherpesvirus pathogenesis in mice. (
  • In the next round of infection this led to the alteration of early events in lytic replication including the deposition of the ORF75C tegument protein, the accelerated kinetics of viral gene expression, and induction of TNFα release and cell death. (
  • Hepatitis E virus (HEV) is an important human pathogen causing both acute and chronic viral hepatitis E infection. (
  • The innate immune response acts as the first line of defense during viral infection. (
  • Viral infection had not been observed for amoebae, until the Acanthamoeba polyphaga mimivirus (APMV) was discovered in 2003. (
  • Nonetheless, the molecular events during co-infection and the interactions of cell, giant virus, and virophage have not been elucidated, yet. (
  • During acute infection there are extremely high levels of virus replication with seeding throughout lymphoid tissues and the brain. (
  • It is becoming increasingly clear that organisms have developed a variety of mechanisms to fight against viral infection. (
  • We further demonstrate that viral replicase activity is responsible for inhibiting subsequent infection. (
  • IMPORTANCE Superinfection, the sequential infection of a single cell by two or more virions, plays an important role in determining the replicative and evolutionary potential of influenza A virus (IAV) populations. (
  • In addition to the yearly burden of seasonal influenza viruses, novel zoonotic IAV strains periodically emerge into humans from swine or birds, triggering unpredictable pandemics that can dramatically increase infection and mortality rates ( 2 ). (
  • Finally, increasing the frequency of coinfection can accelerate viral replication kinetics and virus output by increasing the average multiplicity of infection (MOI) ( 13 - 15 ). (
  • One of the primary means by which coinfection can occur is superinfection, the sequential infection of one cell by multiple viral particles. (
  • The type of lesion produced and the course of infection within the CNS depends on the age and immunocompetence of the host, as well as the neurotropic and immunosuppressive properties of the virus. (
  • Viral infection within neurons is non-productive as nucleocapsids are produced but not released from the surface of the cell. (
  • IgM antibodies appear in the sera approximately 7 days following exposure to vaccine virus or natural infection and decline to undetectable levels after approximately 4 weeks. (
  • We have shown that semen boosts HIV-1 infection and contains fragments of prostatic acid phosphatase (PAP) forming amyloid aggregates termed SEVI (semen-derived enhancer of viral infection) that promote virion attachment to target cells. (
  • Despite its importance for the global spread of HIV-1, however, the effect of semen on virus infection is controversial. (
  • B) Effect of treatment of virus stocks with 90% (v/v) of SE on R5 HIV-1 infection. (
  • Thanks, CYA There is some evidence that one strain of a virus can reduce the severity of co-infection from another strain. (
  • A couple of good references are:- Chambers & Webster (1991) Protection of chickens from lethal influenza virus infection by influenza A/chicken/Pennsylvania/1/83 virus: characterization of the protective effect. (
  • In this paper we investigate in depth a model for the dynamics of a phenotypically heterogeneous population of viruses whose propagation is limited to two-dimensional geometries, and where host cells are able to develop defenses against infection. (
  • Capitán JA, Cuesta JA, Manrubia SC, Aguirre J (2011) Severe Hindrance of Viral Infection Propagation in Spatially Extended Hosts. (
  • The survival of RNA viruses depends, among others, on host's ability to fight infection, on its capacity to defeat the parasite through the immune system, and on the features of the environment where infection takes place. (
  • We demonstrate that TRIM21 enables the RNA sensor RIG-I to detect infection by an incoming RNA virus and the DNA sensor cGAS to detect infection by a DNA virus. (
  • In the final part of our manuscript, we illustrate that this system confers an advantage to the host in vivo by demonstrating that there is a rapid TRIM21-dependent inflammatory response in mice upon viral infection, whereas in the absence of TRIM21 production of crucial cytokines like interferon is delayed. (
  • Consequently, TRIM21 is activated during infection by diverse pathogens including non-enveloped viruses and intracellular bacteria [ 3 ]. (
  • Upon in vivo challenge with mouse adenovirus 1 (MAV-1), mice lacking TRIM21 succumb to fatal viral infection within 7 days [ 5 ]. (
  • This rapid degradation of incoming viral particles provides a potent block to infection [ 1 , 6 ]. (
  • Research on Ebola virus (EBOV) has focused on preventing and controlling the infection using vaccines and antiviral therapies. (
  • Given the long-term challenge of the current epidemic and the likelihood of future outbreaks of viral hemorrhagic fevers caused by the filoviruses, including EBOV and Marburg virus, efforts should also focus on developing therapies to reduce the deadly complications of infection with these viruses [ 1 , 2 ]. (
  • The loss of essential genetic information causes abortive viral replication, which can be rescued by co-infection with a helper virus that possesses an intact genome. (
  • No host for a productive viral infection has been found and the phage may be defective. (
  • Effect of influenza virus infection on key metabolic enzyme activities in MDCK cells. (
  • In eukaryotes, type 1 IFN is essential for defense against virus infection and is a major component of antimicrobial defenses and the innate immune response. (
  • During virus infection of epithelial cells, IFN-β is typically induced first, followed by signaling events that drive the expression of IFN-α subtypes. (
  • Virus infection also induces IFN-λ expression and, in certain cell types, the additional type 1 IFNs can be produced. (
  • These actions mark the innate immune response and the first stage of the global immune response to virus infection. (
  • Isaacs and Lindenmann discovered what we know as type 1 IFN and described its virus-induced, cell-derived, and soluble nature and defined antiviral actions that interfere with virus infection ( 2 , 3 ). (
  • At the time, Alick Isaacs was studying the infection properties of IAV and other RNA viruses, including a variety of mosquito-transmitted viruses, such as West Nile virus. (
  • Indeed, the eclipse phase is a period of viral disassembly and synthesis occurring right after virus entry into the host cell during acute infection, thus reflecting the specialized and parasitic virus life cycle. (
  • A variety of defective clones were also isolated following infection of rat cells with Moloney virus. (
  • However, efficient infection of cells in vitro was not achieved with this mutant virus, possibly due to the absence of virus-specific receptors on the cells. (
  • The concept is simple: virus infection is restricted to neighboring cells by a semisolid overlay. (
  • For most animal viruses, one infectious particle is sufficient to initiate infection. (
  • If it is the case that the smaller genomes of DIPs are more efficiently replicated than the full length viral genome, then why is the interference not sufficient to eliminate the viral infection? (
  • Defective interfering particles arise when virus infections are carried out serially at high multiplicity of infection. (
  • Persistent infection of some standard cell lines by lymphocytic choriomeningitis virus. (
  • The U.S. President's Emergency Plan for AIDS Relief (PEPFAR), the largest bilateral funder of human immunodeficiency virus (HIV) prevention and control programs worldwide, currently supports implementation of preexposure prophylaxis (PrEP) to reduce HIV incidence among persons at substantial risk for infection, including female sex workers, men who have sex with men (MSM), and transgender women (hereafter referred to as key populations). (
  • These data suggest that the biology of abortive infection in the patient samples may be linked to a defect in the production of early and late viral transcripts. (
  • Identification of factors leading to abortive infection will be crucial to understanding the low viral replication in patient samples. (
  • Essential genes are deleted so the virus cannot replicate and produce continued infection. (
  • Major advances in characterizing viral replication have led to the development of direct-acting anti-viral (DAAs) therapies that have considerably improved patient treatment outcome and can even cure chronic infection. (
  • What does viral infection look like in early, late, and very late stages? (
  • Viruses have often been observed in association with the dense microvilli of polarized epithelia as well as the filopodia of nonpolarized cells, yet whether interactions with these structures contribute to infection has remained unknown. (
  • Any disruption of virus cell surfing significantly reduces viral infection. (
  • Our results reveal another example of viruses hijacking host machineries for efficient infection by using the inherent ability of filopodia to transport ligands to the cell body. (
  • Our studies suggest that virus cell surfing along filopodia represents a novel mechanism by which viruses use host cell machineries for efficient infection. (
  • The project is based on the discovery that genomic segments of influenza A viruses (IAV) harboring deletions can arise in the context of natural infection and can induce formation of DIPs and blockade of viral replication. (
  • Considering the very short generation time for a virus, and the high error rate associated with the reverse transcription step of HBV replication, decades of HBV infection are probably equivalent to million years of human evolution. (
  • With the cloning of the HBV genome, it became apparent that the viremia titer (number of infectious virus particles) is highest during the HBeAg phase of infection, declines by several logs during the anti-HBe phase, and disappears at the anti-HBs phase (Fig. 1 ). (
  • Dubensky TW, Murphy FA, Villarreal LP (1984) Detection of DNA and RNA virus genomes in organ systems of whole mice: Patterns of mouse organ infection by polyoma virus. (
  • It's not just a viable virus that wants to spread the infection, but there are also other products like defective particles that might actually limit the infection. (
  • This effect was independent of PRRSV-derived antigens, highlighting the utility of the RP to investigate the host immune response to viral infection. (
  • In this study, we show that GAPDH is incorporated into the virions and the suppression of GAPDH packaging inside the virions enhances viral infection owing to the high reverse transcription efficiency. (
  • The largest of these RNAs, DIssA (molecular weight [mw], 5.2 x 10 6 ), is identical to the genomic RNA packaged in the defective interfering particles produced from these cells. (
  • Makino, S , Fujioka, N & Fujiwara, K 1985, ' Structure of the intracellular defective viral RNAs of defective interfering particles of mouse hepatitis virus ', Journal of virology , vol. 54, no. 2, pp. 329-336. (
  • Thus, some incomplete virions are produced, defective interfering particles (Dis). (
  • Our research team will focus on establishing design principles to engineer potential antiviral agents relying on Defective Interfering Particles (DIPs). (
  • Artifacts caused by defective interfering particles or breakdown of RNA were excluded. (
  • He identified the origins of defective interfering particles of negative-strand RNA viruses. (
  • Alice Huang's research focused on defective interfering particles (DIPs) which can be utilized to combat viruses. (
  • A system for production of defective interfering particles in the absence of infectious influenza A virus. (
  • Read more about A system for production of defective interfering particles in the absence of infectious influenza A virus. (
  • His work on persistent infections lead to important discoveries about genome interactions between infecting viruses and the defective-interfering particles that they generate. (
  • Some researchers believe that such 'defective interfering particles' (which may not be able to replicate to high levels in the absence of a helper virus) could be a future therapy for some viral diseases. (
  • Bangham & Kirkwood (1993) Defective interfering particles and virus evolution. (
  • Defective interfering particles (DIPs) are internal deletion mutants of viruses that replicate at the disbursement of the parent virus. (
  • This review article aimed at reviewing current science on defective interfering particles of their molecular and immunological features, role in disease progression and persistence, impact on vaccine production and viral vectors, and future directions. (
  • Defective interfering particles are very important to the field of biotechnology due to their nature of stimulating the immune system and attenuating some of the live viruses during live-attenuated vaccine production, however, they have a devastating effect like interfering with vaccine production, i.e., decrease in the viral titer, and facilitate pathogenesis and persistence of some viral infections. (
  • Production of defective interfering particles of influenza A virus in continuously cultured bioreactors at two residence times - insights from within-host virus dynamics. (
  • Could you explain the effect of defective interfering particles and how they affect the final titer of the stocks? (
  • Dr. Racaniello, I would like to expand on David Loria's question as well as inquire about potential therapeutic uses for defective interfering particles (DIPs) or genetically modified DIPs. (
  • Culture media from these cells were not infectious and showed no evidence of defective interfering particles. (
  • 9. Interference and Defective Interfering Particles. (
  • Prerna Arora and Najat Bdeir are investigating how defective interfering particles (DIPs) can be exploited for influenza therapy and prevention. (
  • This transition is associated with reduced, or abolished, viral gene expression which probably explains, at least in part, viral evasion of the host immune system [1], Persistent infections have also been established by use of tissue culture cells in vitro [2], although the molecular details involving defective interfering particles may be substantially different from in vivo persistent infections as a consequence of modified selection pressures. (
  • These are also known as defective interfering particles, and can no longer replicate and spread themselves. (
  • John Yin , a University of Wisconsin-Madison chemical engineering professor - along with colleagues from chemical and biological engineering and the interdisciplinary Wisconsin Institute for Discovery , where Yin is a faculty member - plans to find out if these defective interfering particles, documented previously in mouse coronaviruses, exist in human coronaviruses as well. (
  • By understanding the relationships between virus, defective interfering particles and hosts, it may be possible to manipulate the environment to control or slow the spread of the virus. (
  • Influenza viruses can infect many different animals including birds and pigs, which can serve as vectors and reservoirs, respectively. (
  • Influenza viruses have interesting microbiology. (
  • To date, influenza virus DI particles have been reported primarily as a phenomenon of cell culture and in experimentally infected embryonated chicken eggs. (
  • Using a sequencing approach, we characterize several subgenomic viral RNAs from human nasopharyngeal specimens infected with the influenza A(H1N1)pdm09 virus. (
  • An avian influenza virus A(H7N9) reassortant that recently emerged in the United States with low pathogenic phenotype does not efficiently infect swine. (
  • Evidence for a Novel Mechanism of Influenza Virus-Induced Type I Interferon Expression by a Defective RNA-Encoded Protein. (
  • Influenza A virus (IAV) defective RNAs are generated as byproducts of error-prone viral RNA replication. (
  • Making Better Influenza Virus Vaccines? (
  • Killed and live influenza virus vaccines are effective in preventing and curbing the spread of disease, but new technologies such as reverse genetics could be used to improve them and to shorten the lengthy process of preparing vaccine seed viruses. (
  • Finally, universal influenza virus vaccines seem to be within reach. (
  • These new strategies will be successful if they are supported by regulatory agencies and if a robust market for influenza virus vaccines against interpandemic and pandemic threats is made and sustained. (
  • Influenza virus vaccines were first developed in the 1940s and consisted of partially purified preparations of influenza viruses grown in embryonated eggs. (
  • To this day, it remains the basis for the manufacturing process of our influenza virus vaccines. (
  • neuraminidase [NA] subtype 1), an H3N2 influenza A virus, and an influenza B virus. (
  • Because of this bureaucratic roadblock, the H3N2 component of the 2003-2004 influenza virus vaccine was antigenically "off" and showed suboptimal efficacy. (
  • Also, because the cumbersome classical reassortment technique used for preparing the appropriate seed strains makes the yearly process of manufacturing influenza virus vaccines unnecessarily lengthy, new variants first appearing early in the season are rarely considered for the vaccine formulation of the following winter. (
  • Most influenza virus vaccines used in the United States and Europe consist of embryonated egg-grown and formaldehyde-inactivated preparations, which, after purification, are chemically disrupted with a nonionic detergent (for example, Triton X-100). (
  • Defining the specific factors that govern the evolution and transmission of influenza A virus (IAV) populations is of critical importance for designing more-effective prediction and control strategies. (
  • Influenza A viruses (IAV) are estimated to cause hundreds of thousands of deaths across the world every year during seasonal epidemics, despite widespread preexposure and vaccination ( 1 ). (
  • Defining the specific factors that influence the evolution of influenza viruses is critical for designing more-effective vaccines, therapeutics, and surveillance strategies. (
  • Medically speaking, however, influenza is a very specific family of viruses that cause a reasonably narrow set of problems for humans. (
  • Influenza A is a versatile virus with many distinct serotypes. (
  • Influenza is an RNA virus encoded by just 11 genes on 8 separate RNA segments. (
  • With only 11 genes, you can see that influenza is a relatively simple virus. (
  • If you infect an animal with a defective influenza virus for example, that virus can interfere with a virulent strain inoculated into the animal at the same time. (
  • Influenza defective interfering (DI) particles are replication-incompetent viruses carrying large internal deletion in the genome. (
  • Despite reports of DI particles present in seasonal influenza A H1N1 infections, their existence in human infections by the avian influenza A viruses, such as H7N9, has not been studied. (
  • Influenza DI-RNA is known as a defective viral RNA with single large internal deletion. (
  • Virus-Wirtszell-Interaktion bei der Produktion von Influenza A Impfstoff in tierischer Zellkultur: Änderungen des Proteoms von Produktionszelllinien. (
  • Dynamics of influenza A virus defective interfering particle replication. (
  • Improving purification of influenza virus-like particles using a pseudo-affinity strategy. (
  • Sulfated cellulose membrane adsorbers as a platform technology for purification of cell culture-derived influenza virus particles. (
  • The discovery of IFN was driven by the new field of virology ( 1 ) and studies of influenza A virus (IAV) in the 1950s through which the interferon was defined by Alick Isaacs and Jean Lindenmann. (
  • HSV/MHC class I restriction/immune recognition/antigen processing/antigen presentation/influenza virus. (
  • This illustrates that in contrast to the allogeneic and influenza specific responses, the recruitment of herpes virus-specific Ag into the Ag-processing pathway is dependent on a cellular function that is also required for viral maturation and egress. (
  • Compans, R. W., Choppin, P. W.: The structure and assembly of influenza and parainfluenza viruses. (
  • Additionally, an RP influenza vaccine administered 24 hours prior to PRRSV challenge reduced viremia and viral load in young pigs compared to controls. (
  • Viruses have evolved by borrowing and modifying cellular genes to become extremely efficient at nucleic acid delivery to different cell types, avoiding at the same time immunosurveillance by an infected host. (
  • Do captured viral genes make human pregnancies possible? (
  • One remarkable conjecture concerns viral genes that became embedded in the genomes of the forerunners of mammals. (
  • Beyond shedding light on placental evolution, these viral genes could provide insight into pregnancies that go awry. (
  • Investigators are already examining whether the genes are defective in women who have had problem pregnancies. (
  • Unlike their viral relatives, retroviruses have adopted a strategy for permanently inserting a copy of their genes into the genomes of the cells they invade. (
  • Previous attempts to investigate intrahost genetic variation in DENV characterized only a few viral genes or a limited number of full-length genomes. (
  • Interestingly, a strong association was discerned between the extent of intrahost diversity in a few genes and viral clade identity. (
  • PB2∆ induces the expression of IFNβ and IFN-stimulated genes by direct interaction with the cellular adapter protein MAVS, thereby reducing viral replication of IFN-sensitive viruses such as IAV or vesicular stomatitis virus. (
  • IAV particles that express a complete set of viral genes potently inhibit superinfection, while semi-infectious particles (SIPs) that express incomplete subsets of viral genes do not. (
  • Here, we show that superinfection susceptibility is determined by the total number of viral genes expressed within a cell and is independent of their specific identity. (
  • Regardless of their origin and family, viruses have evolved elegant strategies to reach and enter specific target cells where they seize the cellular machinery to express viral genes and assemble progeny particles. (
  • In the same way, viral vectors represent the most effective means of gene transfer to modify specific cell type or tissue, and can be manipulated to express therapeutic genes. (
  • Viral vectors are usually derived from parental wild type viruses whose viral genes (essential for replication and virulence) have been replaced with the heterologous genes intended for cell manipulation. (
  • Specific viruses have been picked as gene delivery vehicles according to their capacity to carry foreign genes, as well as their ability to conveniently deliver genes that are linked to efficient gene expression. (
  • To generate a vector, coding genes and so-called cis -acting regulatory sequences must be separated into distinct nucleic acid molecules in order to prevent their reconstitution and formation of productive viral particles. (
  • Then inject them into patients carrying abnormal genes where they will deliver their therapeutic cargoes inside the defective target cells. (
  • In theory, the good DNA replaces or corrects the abnormal function of the defective genes, rendering previously impaired cells whole, normal and healthy. (
  • As the vector genome carries no virus genes, amplicons are both non-toxic for the infected cells and non-pathogenic for the inoculated organisms. (
  • Defective, replication-incompetent non-pathogenic recombinant HSV-1 vectors lack one or more essential replication genes, but retain many advantageous features of wild-type HSV-1, particularly the ability to express transgenes after having established latent infections in central and peripheral neurons. (
  • Amplicon vectors are defective, helper-dependent vectors that carry no viral genes and take advantage of the large carrier capacity of the virus particle to deliver long transgenic sequences. (
  • In other instances, the particles do not have a genome at all, or one or more genes are missing (genetically defective viruses). (
  • The capsid protein substitution mutants, having capsid protein genes of MPyV, for which receptors are present on a variety of cell types, showed also no cytopathic effect, despite an enhanced viral DNA replication and assembly of virus particles. (
  • To understand this complex system, the team will use what is known about the virus's growth and spread to build mathematical models incorporating the ways the virus enters cells and expresses genes. (
  • Tetracistronic minigenomes, which consist of Ebola virus non-coding regions, a reporter gene, and three Ebola virus genes involved in morphogenesis, budding, and entry (VP40, GP 1,2 , and VP24), can be used to produce replication and transcription-competent virus-like particles (trVLPs) containing these minigenomes. (
  • In theory at least, it should be possible to treat a number of devastating diseases by patching in bits of DNA to repair defective or missing genes. (
  • Ribosome Recognition and Translation of Vesicular Stomatitis Virus Messenger RNA 4. (
  • RNQ Synthesis by Defective Interfering Vesicular Stomatitis Virus Particles 11. (
  • Defective interfering T particles of vesicular stomatitis virus provide remarkable protection against viral disease and death when introduced intracerebrally in large numbers along with an otherwise rapidly fatal low dose of standard infectious virus. (
  • In the late 1970s and early 1980s he identified genomic sequences for vesicular stomatitis virus (VSV) and rabies virus (RABV), members of the Rhabdoviridae family of viruses, and for Ebola virus and Marburg virus from the broader group of negative-strand RNA viruses (NSRV). (
  • Over the past 40 years, vesicular stomatitis virus (VSV), closely related to rabies virus, has served as a paradigm to study the fundamental molecular mechanisms of transcription and replication of NNS RNA viruses. (
  • Vesicular stomatitis Indiana virus [hereafter simply called vesicular stomatitis virus (VSV)] is an arthropod-borne animal virus belonging to the Vesiculovirus genus in the Rhabdoviridae family. (
  • While at Johns Hopkins University, Huang conducted research looking into the inhibition of cellular RNA synthesis by nonreplicating vesicular stomatitis virus. (
  • The vesicular stomatitis virus (VSV), known to infect horses, cattle and swine, was the virus she first chose to study. (
  • Later, in her work with her husband at Massachusetts Institute of Technology, one of the vesicular stomatitis viruses (VSV) she studied made ribonucleic acid (RNA) from RNA instead of DNA (deoxyribonucleic acid), which did not follow the conventional central dogma: DNA RNA Protein. (
  • In her postdoctoral work at the Salk Institute and MIT with David Baltimore, Dr. Huang worked on vesicular stomatitis virus (VSV) and discovered that these viruses had RNA-dependent RNA-polymerase. (
  • Huang and Baltimore coauthored a paper with Martha Stampfer titled "Ribonucleic acid synthesis of vesicular stomatitis virus, II. (
  • A remarkable homology of the RABV L protein to a counterpart in vesicular stomatitis virus, a well-characterized rhabdovirus, suggests that it catalyzes mRNA processing reactions, such as 5′-capping, cap methylation, and 3′-polyadenylation, in addition to RNA synthesis. (
  • Studies on transcription and replication of rhabdoviruses have been carried out mainly using vesicular stomatitis virus (VSV, an arthropod-borne animal vesiculovirus) as a model (reviewed in Reference [ 8 ]), because VSV can be safely handled and shows the strongest RNA synthesis activity among rhabdoviruses as well as other NNS RNA viruses belonging to different families. (
  • For the last 20 - 25 years of his scientific career, Holland focused his studies on vesicular stomatitis virus (an RNA-containing rhabdovirus) as a model system for viral persistence and for the study of evolution of viral genomic RNAs. (
  • Ehrenfeld, E., Summers, D. F.: Adenylate-rich sequences in vesicular stomatitis virus messenger ribonucleic acid. (
  • An alternative approach to structurefunction analysis of vesicular stomatitis virus (VSV) gene products and their interactions with one another during each phase of the viral life cycle is described. (
  • Signs of viral budding-vesicular appearance of cells. (
  • Analogous to observations in RNA viruses such as human immunodeficiency virus, genetic variation associated with intrahost dengue virus (DENV) populations has been postulated to influence viral fitness and disease pathogenesis. (
  • She thought that these mutants played a vital role in viral pathogenesis and could possibly be used to prevent disease. (
  • As these defective proviruses are unable to encode intact and replication-competent viruses, they have long been thought of as biologically irrelevant "graveyard" of viruses with little significance to HIV-1 pathogenesis. (
  • The pathogenesis of this appears to be based on an immunological reaction against the basic protein in myelin that is triggered by the distemper virus. (
  • It has been proposed that defective interfering viral particles may play a role in the pathogenesis. (
  • Further investigations on this overwhelming generation of DI-RNA may provide important insights into the understanding of H7N9 viral replication and pathogenesis. (
  • Here we will describe a novel approach using whole animal sections and compare the strengths and weaknesses of this system with other techniques employed for studying viral pathogenesis. (
  • These mutations selectively abrogate the ability of LT-Ag to support viral replication while still maintaining its Rb-binding activity, suggesting a continuous requirement for LT-Ag mediated cell cycle deregulation during MCC pathogenesis. (
  • DI particles are recognized for the role they play in inhibiting viral replication and for the impact they have on the production of infectious virions. (
  • They contained different subsets of the genomic sequences from those of the standard intracellular mRNAs of nondefective mouse hepatitis virus JHM strain. (
  • The conformation of the dimeric genomic RNA is different within immature and mature particles, as demonstrated by differences in the electrophoretic mobility and thermostability of the dimer ( 12 , 42 ). (
  • Recent genomic and metagenomic studies have led to a dramatic expansion of the known diversity of nucleocytoplasmic large DNA viruses (NCLDVs) of eukaryotes, which include giant viruses of protists and important pathogens of vertebrates, such as poxviruses. (
  • This is a function of both the segmented nature of the viral genome and the enormous amount of genomic heterogeneity present within IAV populations ( 3 , 4 ). (
  • Biochemistry experiments revealed that HvCCR4 was recruited into N-RNA complexes by the BYSMV P protein and triggered turnover of N-bound cellular mRNAs, thereby releasing RNA-free N protein to bind viral genomic RNA for optimal viral replication. (
  • In vitro and clinical use of viral vectors is based on RNA and DNA viruses that differ in their genomic structures and host range. (
  • Perhaps his most influential findings resulted from experiments devoted to quantitation of the rates of mutation during the replication of viral genomic RNAs. (
  • The invention concerns the use of a nucleotide sequence derived from all or part of the genomic RNA 5′ end of a type C retrovirus except for Friend murine leukaemia virus (FMLV) and Moloney murine leukaemia virus (MoMLV) as internal ribosome entry site or as element enabling or improving retrovirus. (
  • An optimized reverse transcription (RT)-PCR protocol for the intravitam detection of rabies virus genomic RNA was tested with clinical samples obtained from 28 patients suspected of having rabies, 9 of whom were confirmed to have had rabies by postmortem examination. (
  • POL The genomic region encoding the viral enzymes protease, reverse transcriptase, and integrase. (
  • In addition to recombining with other viral genomes, viruses may also recombine with the genome of their host, either as an obligate step of their replication cycle, or accidentally ( Weiss 2017 ). (
  • This extensive genetic variability originates from the accumulation of genetically distinct genomes in individual hosts (referred to here as intrahost diversity) due to the error-prone nature of the enzyme responsible for viral RNA replication, the viral RNA-dependent RNA polymerase (RdRp) ( 16 ). (
  • The order Mononegavirales comprises highly diversified eukaryotic viruses with a monopartite negative strand RNA genome (rarely bipartite genomes), which includes important human pathogens [e.g., rabies virus (RABV), measles virus (MeV), Nipah virus (NiV), human respiratory syncytial virus (HRSV), Ebola virus (EBOV)] ( Lamb, 2013 ). (
  • Since gene products as well as RNA genomes of these non-segmented negative strand (NNS) RNA viruses share structural and functional similarities, they are believed to have evolved from a common ancestor. (
  • We sequenced the complete genomes of three viruses infecting crustaceans, the Caribbean spiny lobster. (
  • Five classes of viral vector can be categorized in two principal groups, according to whether their genomes integrate into host cellular chromatin (lentiviruses and oncoretroviruses) or persist in the cell nucleus predominantly as extrachromosomal episomes (adenoviruses, adeno-associated viruses and herpes viruses). (
  • The adaptive ability of RNA viruses is a consequence of the vast genetic diversity of their populations, composed by a large number of individuals that replicate their genomes at a mutation rate several orders of magnitude higher than that of cellular DNA [2] . (
  • Unfortunately, almost all viruses utilize a strategy of encapsidation, comprising a protein shell that protects their genomes and impedes them from being sensed or degraded. (
  • In our study, we describe how components of innate and adaptive immunity combine to allow the rapid sensing of genomes from incoming viruses. (
  • We hypothesized that this catastrophic uncoating might also expose viral genomes for sensing by nucleic acid pattern recognition receptors (PRRs). (
  • Despite the presence of numerous cytosolic PRRs that recognize pathogen nucleic acids, it is often viral transcripts or progeny genomes, as opposed to incoming genomes, that are detected [ 7 , 8 , 9 ]. (
  • At present it is generally accepted that "one of the most striking features that distinguishes retroviruses from all other animal viruses is the presence, in the chromosomes of normal uninfected cells, of genomes closely related to, or identical with, those of infectious viruses"80. (
  • Baltimore, D.: Expression of animal virus genomes. (
  • Examples include the genomes of some (+) strand RNA viruses of plants, which consists of two RNA molecules that are packaged in different particles. (
  • Is this because of a low probability of coinfection between DIPs and viruses with full length genomes? (
  • In the simplest case, DI particles are unable to produce a complete viral capsid, and therefore the DI genomes can only be packaged when a wild-type virus co-infects the same cell. (
  • When a deletion occurs in the viral genome - possibly by polymerase skipping, which happens randomly - those smaller genomes replicate faster than wild type genomes and eventually interfere with replication of wild type virus. (
  • All integrated viral genomes recovered from MCC tissue or MCC cell lines harbor signature mutations in the early gene transcript encoding for the large T-Antigen (LT-Ag). (
  • Like DIPs, vaccines also use a defective version of viruses, but as a preventive treatment building immune memory rather than a curative treatment based on competition and co-evolution. (
  • The defective and parasitic nature of DIPs may someday be used to reduce and even completely suppress the occurrence of the vaccine-derived disease types, while also helping to prevent the virus from spreading just as effectively as with traditional vaccines. (
  • Many types of viral vectors have been used in a wide array of basic and clinical studies, and genetic tools made possible to construct novel viruses intended for gene therapy, but also the development of vaccines. (
  • By taking advantage of these new technologies, we could develop live vaccines that would be safe, cross-protective against variant strains, and require less virus per dose than conventional vaccines. (
  • Furthermore, pandemic vaccines against highly virulent strains such as the H5N1 virus can only be generated by reverse genetics techniques. (
  • This technology, which originated from uses for military purposes, revolutionized the purification process and industrial production of many viruses for vaccines. (
  • The split virus preparations show lower pyrogenicity than whole virus vaccines. (
  • Stirred tanks in cascades and plug-flow tubular bioreactors for continuous production of viral vaccines. (
  • A single-use chromatographic purification platform for viral gene transfer vectors & viral vaccines. (
  • Cell Culture-based Viral Vaccines: Process Intensification and Monitoring. (
  • A universal platform for continuous manufacturing of viral vaccines & gene therapy vectors. (
  • Alphaviruses are positive-strand RNA viruses that can mediate high-level gene expression in mammalian cells, and members of this family have served as a basis for viral vector and DNA plasmid vaccines for infectious diseases and cancer (reviewed in ref. 14 ). (
  • With your donation you can support them in developing drugs and vaccines against the virus or in deciphering the mechanisms of disease development and progression. (
  • There are no approved vaccines or specific treatments for the disease caused by these viruses, and work with infectious Ebola viruses is restricted to biosafety level 4 laboratories, significantly limiting the research on these viruses. (
  • Alphavirus-derived replicon particle (RP) vaccines have demonstrated efficacy and safety in a wide range of disease and animal models. (
  • Recently, an RP platform derived from Venezuelan equine encephalitis virus (strain, TC-83) was developed for use in veterinary vaccines, including vaccines for swine. (
  • The intracellular defective RNAs generated during high-multiplicity serial passages of mouse hepatitis virus JHM strain on DBT cells were examined. (
  • Seven novel species of single-stranded polyadenylic acid-containing defective RNAs were identified from passages 3 through 22. (
  • Thus these novel intracellular viral RNAs were identified as defective interfering RNAs of mouse hepatitis virus JHM strain. (
  • The possible mechanism for the generation of defective interfering RNAs was discussed. (
  • The distribution of these in vivo -derived DI-like RNAs was similar to that of in vitro DIs, with the majority of the defective RNAs generated from the PB2 (segment 1) of the polymerase complex, followed by PB1 and PA. (
  • To determine whether these RNA species were functional as messengers in infected cells, virus-specific RNAs present in polyribosomes were analyzed. (
  • In addition, we examined the expression of DI-RNAs in mice infected with sublethal dose of H7N9 virus at different time points. (
  • Collins, B. S., Bratt, M. A.: Separation of the messenger RNAs of Newcastle disease virus by gel electrophoresis. (
  • The research collaboration will focus on poliovirus, the virus responsible for poliomyelitis , a highly infectious disease that mainly affects children, and 1 in 200 infections leads to irreversible paralysis 3 . (
  • RNA respiratory viral infections in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice. (
  • Genetic interaction of cell and virophage might constitute a potent defense machinery against giant viruses and seems to be important for survival of the infected cell during mimivirus infections. (
  • However, regulation of CCR4 in virus infections is less understood. (
  • Currently, regulation of CCR4 and its deadenylase activity in viral infections is not well understood. (
  • The Y-axis gives average values of triplicate infections, and the X-axis gives the final dilution of the virus stocks. (
  • Some very far-reaching conclusions about the nature of virus-virus and virus-cell interactions during viral infections have emerged from Holland's research efforts. (
  • Our aim is to better understand propagation of viral infections with mobility restrictions, e.g., in crops or in plant leaves, in order to inspire new strategies for effective viral control. (
  • While the term "sepsis" is generally used in the context of bacterial and fungal infections, all microorganisms, including viruses, can cause sepsis. (
  • Clones of cells were isolated from single virus-single cell infections of NIH/3T3 cells with Moloney murine leukemia virus. (
  • Why they arise at high moi infections is not known but might be related to their ability to out-compete wild type virus when replication factors are limiting, as would be the case when many viruses infect a cell. (
  • Persistent infections by LCMV can be maintained without expression of extracellular virus particles and without appearance of large amounts of viral antigens on the cell surface. (
  • IFNs are potent antiviral cytokines that are critical in the first line of defense against viral infections and have important functions in shaping the adaptive response [ 10 ]. (
  • There are many examples of acute viral infections that have the potential to develop into prolonged latent or persistent infections. (
  • Southern PJ, Oldstone MBA (1986) Medical consequences of persistent virus infections. (
  • Southern PJ, Blount P, Oldstone MBA (1984) Analysis of persistent virus infections by in situ hybridization to whole-mouse sections. (
  • This interference hinders the parent virus and enables the antiviral agents to replicate and spread, until the virus is completely gone and no more of the essential elements the agents lack remain available. (
  • Like other viruses, retroviruses must sneak their genetic material into cells and command a cell's internal machinery to replicate themselves. (
  • Elucidation of their unique strategies to replicate in eukaryotic cells is crucial to aid in developing anti-NNS RNA viral agents. (
  • Dr. Huang and Dr. Baltimore unraveled that RNA viruses were different and used RNA polymerase to replicate its RNA genome. (
  • The failure of KV DNA to replicate in mouse fibroblast cells after transfection suggested that viral gene expression had narrow cell specificity. (
  • The substitution mutant was able to replicate in transfected 3T3 cells, and the newly replicated viral DNA associated with protein to form particles with the density of virions in CsCl equilibrium gradients. (
  • The enhancer substitution mutant (KVm1), having a transcriptional enhancer substituted with a corresponding DNA segment from MPyV, was able to replicate in mouse 3T3 cells and form virus particles that were infectious in mice. (
  • Consistent with their enhanced pathogenicity, core promoter mutants were found to replicate at up to 10-fold higher levels in transfected human hepatoma cells than the wild-type virus. (
  • When RNA viruses, which include coronaviruses, replicate, the process produces lots of partial viruses, mutations and other "junk. (
  • An ongoing problem preventing full eradication of the disease is the occurrence of vaccine-derived poliovirus, a new instance of the disease caused when the vaccine strain mixes with other closely related viral species. (
  • New vaccine and therapy against non-A non-B viral hepatitis, and their preparation process. (
  • Virus antigen, method for its preparation and its use in diagnosis and therapy (as a vaccine). (
  • A myriad of viral vaccine vectors can also induce apoptosis in the target cell. (
  • Recombinant viral vectors have also been used to deliver human immunodeficiency virus (HIV) gene products, in conjunction with a protein boost using env-gp120 when searching for HIV vaccine, but results have been largely disappointing. (
  • Specifically, the 2005-2006 vaccine formulation is made up of the A/New Caledonia/20/99 (H1N1), A/California/7/2004 (H3N2), and B/Shanghai/361/2002 viruses. (
  • Changes in the HA of circulating viruses (antigenic drift) require periodic replacement of the vaccine strains during interpandemic periods. (
  • Based on existing knowledge and data, we set out to generate a single-dose, non-replicating vaccine capable of forming EBOV-like particles (VLPs). (
  • The decision to use MVA as an EBOV vaccine platform was, in part, based on its parent, vaccinia virus, which has been successfully used in ring vaccinations to contain local outbreaks during the eradication of smallpox 13 . (
  • Process Intensification in Viral Vaccine Manufacturing. (
  • Intensified cell-based viral vaccine processes: from continuous to perfusion to hybrid systems. (
  • High Yield Viral Vaccine Production: Process Options and Monitoring. (
  • This study investigated the immunogenicity of alphavirus vaccine replicon particles (VRP) that encode PSMA (PSMA-VRP). (
  • A propagation-defective vaccine replicon particle (VRP) vector system has been developed based on an attenuated variant of Venezuelan equine encephalitis virus ( 18 , 19 ). (
  • Finally, there has also been a long-time interest in the development of viral-based vectors as delivery systems in gene therapy and vaccine development with emphasis on HSV-1 and baculovirus. (
  • The synthesis of six of the seven normal mRNA species specific to mouse hepatitis virus JHM strain was completely inhibited when cells were infected with viruses of late-passage levels. (
  • However, the synthesis of RNA7 and its product, viral nucleoprotein, was not significantly altered in late passages. (
  • We have determined the kinetics of virus production and virus-specific RNA synthesis in Sac(−) cells infected with mouse hepatitis virus strain A59 (MHV-A59). (
  • Synthesis of virus-specific RNA, measured by the incorporation of [ 3 H]uridine in the presence of 1 μg/ml actinomycin D, also started at 4 hr pi and its maximum rate occurred between 6 and 8 hr pi. (
  • Bratt, M. A., Robinson, W. S.: Ribonucleic acid synthesis in cells infected with Newcastle disease virus. (
  • Primary Transcription: Early Viral Messenger RNA Synthesis. (
  • Viral Protein Synthesis. (
  • Hall WW, Choppin PW (1979) Evidence for lack of synthesis of the M polypeptide of measles virus in brain cells in subacute sclerosing penencephalitis. (
  • Vif was implicated in a number of functions, but its precise role in viral infectivity remained elusive for a long time. (
  • The 55-kDa Gag precursor is called assemblin to indicate its role in viral assembly. (
  • DENV replication takes place in the cytoplasm of both human and mosquito cells and involves the production of a double-stranded RNA intermediate generated by the virus-encoded RNA-dependent RNA-polymerase (RdRp) ( Bartenschlager and Miller 2008 ). (
  • Her discovery of this VSV virion-associated RNA - dependent RNA polymerase led to Baltimore's research on tumor viruses and the discovery of the enzyme called reverse transcriptase. (
  • Representative compounds from the sulfonamide carboxamide and heteroaryldihydropyrimidine series of CAMs were evaluated and compared to nucleos(t)ide analogs as inhibitors of the viral polymerase. (
  • Oligomerization of core dimers forms icosahedral capsids, within which pgRNA and viral polymerase are encapsidated. (
  • The finding that lyrosine-methionine-aspartate-aspartate (YMDD) motif of the reverse transcriptase domain of hepatitis B virus (HBV) DNA polymerase carries a HLA-A2 restricted cytotoxic T lymphocyte (CII) epitope makes quantitative measurement of the numbers of peptide specific CTLs feasible using MHC tetramer-peptide complex staining. (
  • Quantitative polymerase chain reaction assay for serum hepatitis B Virus DNA as a predictive factor for Post-treatment relapse after. (
  • Any errors made by the polymerase enzyme during the first and the third steps are not subjected to proof reading, the result being pronounced sequence variability".137 Hence, as long ago as 1973, it was concluded that the above phenomena "will prove a stumbling block to any genetic analysis of RNA tumour viruses"138 (RNA tumour viruses=retrovirus). (
  • We showed previously by using the vaccinia viruslT7 RNA polymerase expression system that when cells expressing the nucleocapsid protein (N), the phosphoprotein (NS), and the large polymerase protein (L) of VSV were superinfected with defective interfering (DI) particles, rapid and efflicient replication and amplification of DI particle RNA occurred. (
  • The NS5 protein of ZIKV is the RNA-dependent RNA polymerase (RdRp) in charge of viral genome replication. (
  • Unlike existing drugs that stop viral replication by blocking known viral or cellular processes, DIPs can compete and co-evolve along with viruses. (
  • 2- Sophistically adapted by several thousand years of evolution, viral systems survived because they solved the "no entrance" cellular defenses. (
  • For example, it is not well understood how P binds to N 0 to prevent binding to cellular mRNAs and facilitate specific viral gRNA and agRNA interactions. (
  • Unlike Fc gamma receptors, which phagocytose immune complexes, TRIM21 detects antibody-bound virions that enter the cytosol after attachment of the virus to its specific cellular receptor, endocytosis, and endosomal escape. (
  • Protein expressed at times later than 72 hours may be processed aberrantly, because the large virus load can cause a breakdown of cellular processes. (
  • The work of Hannah Kleine-Weber will investigate the concept that MERS-CoV adaptation to efficient use of the cellular protease TMPRSS2, which activates the viral spike protein, might be a perquisite for robust and sustained human-human transmission and might thus serve as an indicator of the pandemic potential of newly emerging MERS-CoV variants. (
  • Moreover, Mariana González Hernández will determine whether activation of the viral GP by the cellular cysteine proteases cathepsin B and L is required for viral entry into primary target cells and organs ex vivo. (
  • She has identified specific residues in each virus' glycoproteins that are critical for binding cellular Eph family receptor tyrosine kinases and has generated virus mutants that can no longer interact with these molecules. (
  • IFITMs restrict cellular entry of a broad range of enveloped viruses that infect cells through an endocytotic pathway. (
  • The identified antiviral candidates include drugs targeting viral components as well as cellular ones. (
  • Lately, a great effort has been carried out to assay several drug candidates directed to viral targets (direct-acting antivirals) or against cellular targets (host-targeting antivirals). (
  • In fact, nucleoside analogs/derivatives, which target viral but not cellular polymerases to terminate viral RNA replication after incorporation into the viral nascent RNA chain, are usually safe for use in humans ( 12 ), and thus they have been extensively assayed against ZIKV in cell culture and, in some instances, in animal models. (
  • The key attributes of this technology are that RPs are propagation-defective, single-cycle RNA virus vectors, and are capable of eliciting potent humoral and cellular immune responses to a wide variety of antigens. (
  • Vaccinated animals developed specific humoral and cellular immune responses, and also had reduced viremia and viral load post-challenge. (
  • Accumulation of defective interfering viral particles in only a few passages in Vero cells attenuates mumps virus neurovirulence. (
  • This resemblance becomes even more evident with EVs produced by cells productively infected with viruses. (
  • Moreover, we emphasize that in the specific case of virus-infected cells, it is almost impossible to distinguish EVs from (noninfectious) viruses and to separate them. (
  • In full analogy with viral biogenesis, some of these vesicles are generated inside cells and on release into the extracellular milieu are called "exosomes," whereas others pinch off from the plasma membrane and are generally referred to as "microvesicles" ( 1 ). (
  • In contrast to EVs, the definition of viruses developed by 20th century virologists was quite precise: both the Encyclopedia Britannica and the Oxford English Dictionary define virus as "an infectious agent of small size that can multiply only in living cells. (
  • Delivery procedures and availability of target cells upon delivery are important decision factors that significantly influence the spread of vector particles. (
  • The resulting images unexpectedly revealed viruslike particles budding from apparently healthy cells. (
  • The present study was initially designed to survey virus-host recombination events between dengue virus (DENV) and Aedes albopictus mosquito cells by high-throughput (Illumina) sequencing. (
  • Expression of the major viral structural protein, termed the Gag polyprotein, is sufficient for assembly of retrovirus particles in permissive cells. (
  • Lentiviruses have the hability to infect non-dividing cells (this feature is specific of this type of virus among retroviridae) and they are adapted to deliver a large amount of RNA into the target cells. (
  • Greater than 95% of these proviruses detected in circulating peripheral blood mononuclear cells (PBMCs) are referred to as "defective" by virtue of having large internal deletions and lethal genetic mutations. (
  • The article is called "Zika virus selectively kills aggressive human embryonal CNS tumor cells in vitro and in vivo" and was published online this Thursday. (
  • Concentrations of one viral particle per ten cells were sufficient to infect and kill cells derived from AT/RT and medulloblastoma tumors. (
  • In addition, the virus showed high specificity for this type of cells. (
  • The virus did not infect tumor cells indiscriminately," explains Okamoto. (
  • An MA mutant deficient for PI(4,5)P2 binding, 29KE/31KE, has been shown to mislocalize within the cell, leading to particle assembly in a multivesicular body compartment and defective release of cell-free particles in HeLa and 293T cells. (
  • Despite the defect in virus production in these cells, release of the 29KE/31KE mutant is not significantly reduced in primary T cells, macrophages and Jurkat T cells. (
  • Use of MDCK cells for virus isolation is not allowed by FDA's rules, which do not yet encompass advanced technologies or scientifically sound purification procedures based on limiting dilutions or cloning with DNA. (
  • The 75A.stop virus also exhibited defective replication in primary fibroblast and macrophage cells. (
  • Within 4-6 days virus multiplication occurs within lymphoid follicles in the spleen, lamina propria of the stomach and small intestine, mesenteric lymph nodes and Kupffer cells. (
  • Virus, either free or lymphocyte associated, may enter the CNS by entering into mononuclear cells in the meninges, choroid plexus, epithelial cells of the fourth ventricle and ependymal cells lining the ventricular system. (
  • 1. A method of transforming cells surrounding a solid tumor in a mammal, which comprises directly injecting into said solid tumor a viral vector containing a nucleic acid sequence encoding a protein selected from the group consisting of a Class I histocompatibility protein, a Class II histocompatibility protein, a cytokine, diphtheria toxin, and pertussis toxin in an amount effective for transforming said cells, wherein said protein is expressed by said cells. (
  • TZM-bl cells were infected with the indicated dilutions of SE- or PBS-treated virus stocks. (
  • The invention further concerns the use of a vector, a viral particle or a pharmaceutical composition for transfecting or infecting pluripotent stem cells. (
  • However, this situation often ushers in an arms race between the virus and the host cells. (
  • Animal and plant cells can be infected by a variety of viruses, usually with a high degree of specificity. (
  • Our cells have potent immune sensors that can detect the presence of viral nucleic acid in the cytosol. (
  • TRIM21 therefore detects viruses during what could otherwise be a productive infectious event and protects cells of diverse tissue types [ 3 ]. (
  • Herpes simplex virus type 1 (HSV-1)-based vectors have the capacity to deliver up to 150 Kbp of foreign DNA to the nucleus of most proliferating and quiescent mammalian cells, making this family of vectors a very interesting tool for gene transfer and gene therapy. (
  • Recombinant attenuated viruses are replication-competent HSV-1 vectors carrying mutations that restrict spread and lytic viral replication to cancer cells without causing major toxicity to the healthy tissues. (
  • Using tyrosinase as a prototypical melanocyte differentiation antigen, we recently showed that Venezuelan equine encephalitis virus-based VRP induced robust B-cell and T-cell responses and improved survival in mice challenged with B16 melanoma cells. (
  • It had just been realized that viruses were different from bacteria in that they replicated through a means beyond binary fission within animal cells. (
  • Differential recruitment of viral and allo-epitopes into the MHC class I antigen processing pathway of a novel mutant of Ltk- cells. (
  • In HSV-1-infected gro29 cells, viral polypeptides are synthesized in normal amounts and viral assembly takes place. (
  • However, transport of the assembled particles is defective in these cells, resulting in the accumulation of noninfectious virus in cytoplasmic vesicles, and a reduction in the release of viral particles by at least 2000-fold. (
  • One clone produced virus with altered plaque morphology, while others failed to produce particles able to make plaques on XC cells. (
  • However, these particles were noninfectious when tested on 3T3 cells, suggesting that absorption or uptake of virus particles was defective for these cells. (
  • East, J., Kingsbury, D. W.: Mumps virus replication in chick embryo lung cells: properties of RNA species in virions and infected cells. (
  • Kaberin, N. V.: Delay in the incorporation of protein into virus nucleocapsid in Newcastle disease virus infected cells. (
  • While the cell-free virus in genital secretions has been carefully measured (4), the number of genital tract cells infected has been far more difficult to quantitate. (
  • In this case the virus is said to infect cells with one-hit kinetics. (
  • The viruses within the agar plug move into the buffer, which can then be used to infect cultured cells. (
  • The virus destroys defense cells (T-CD4 lymphocytes) and an important increase identifier of immunosuppression and/or failure to an immune response, the early signs often appear in the oral cavity in the form of various lesions. (
  • The vector-supported DI particles were similar in size and morphology to the authentic DI particles generated from cells coinfected with DI particles and helper VSV and their infectivity could be blocked by anti-VSV or anti-G antiserum. (
  • The stable cells supporting replication of DI RNA described in this report will be useful in further examining the innate immune signaling pathways and the host cell functions in viral genome replication. (
  • Vectors are engineered to capitalize on the ability of viruses to infect and transfer genetic material into human cells. (
  • Moreover, ΗCV virus infects not only hepatocytes but also cells of the immune system and neuronal cells and is associated with several extrahepatic diseases. (
  • When should I harvest my protein after I have inoculated my insect cells with recombinant virus? (
  • Viral occlusions-few cells will contain occlusion bodies, which appear as refractive crystals in the nucleus of the insect cell. (
  • Very late cell lysis-a few cells may fill with occluded virus, die, and burst, leaving signs of clearing in the monolayer. (
  • She is studying how the glycoprotein (GP) of ebolaviruses counteract the interferon-induced antiviral host cell factor tetherin and will clarify whether tetherin counteraction is important for viral spread in target cells. (
  • Kenney S, Natarajan V, Strike D, Khoury G, Salzman NP (1984) JC virus enhancer-promoter active in human brain cells. (
  • Oldstone MBA, Buchmeier MJ (1982) Restricted expression of viral glycoprotein in cells of persistently infected mice. (
  • Delivery of virion-associated Vpr via defective HIV-1 particles induced analogous biologic effects in noninfected target cells, suggesting that Vpr may act similarly beyond infected cells. (
  • Viruses like novel coronavirus can be sloppy multipliers, leaving lots of junk particles around infected cells during reproduction. (
  • If that's the case, their next step may be to examine how viruses spread as a mixture of active and defective virus strains and how those particles interact with one another and with their host cells. (
  • In the current gold-standard test, a plaque assay, researchers release a virus onto a dish of cells overlaid with a layer of semi-solid agar to force the virus to spread only to neighboring cells. (
  • We use a primary cell line from the choroid plexus of sheep (SCP cells) for transfection and propagation of the virus 7 . (
  • Suppression of GAPDH expression by RNA interference in CEM/LAV-1 cells resulted in decreased GAPDH packaging inside the virions, and the GAPDH-packaging-defective virus maintained at least control levels of viral production but increased the infectivity. (
  • Furthermore, immunoprecipitation assay using an anti-GAPDH antibody showed that GAPDH directly interacted with Pr55 gag and p160 gag - pol and the overexpression of LysRS in HIV-1-producing cells resulted in a decrease in the efficiency of GAPDH packaging in HIV particles. (
  • In contrast, the viruses produced from cells expressing a high level of GAPDH showed decreased infectivity in TZM-bl cells and reverse transcription efficiency in TZM-bl cells and peripheral blood mononuclear cells (PBMCs). (
  • Once inside, the viral particles were supposed to insert replacement DNA into tissue cells so his liver could start to process ammonia normally. (
  • To try and help solve the problem, biologists and mathematicians from IBM, UCSF, Stanford University, and the University of Haifa are working side-by-side on a DARPA-funded research project to engineer a new type of antiviral agent against viruses such as polio. (
  • After displacing the virus, the antiviral agents will die out because of their inability to survive alone. (
  • Mathematical and computational modeling of virus and defective particles competition at single cell, tissue, organ and host level will allow inference of antiviral design principles. (
  • Evasion of the zinc-finger antiviral protein (ZAP) may drive CpG dinucleotide suppression in HIV-1 and many other viral pathogens but the viral determinants of ZAP sensitivity are poorly defined. (
  • The hepatitis B virus (HBV) core protein serves multiple essential functions in the viral life cycle, and antiviral agents that target the core protein are being developed. (
  • This leads to a broad program of antiviral transcription and induction of an anti-viral state. (
  • A novel type of defective interfering particle for antiviral therapy. (
  • The early innate immune response to viruses like HMPV is characterized by induction of antiviral interferons (IFNs) and proinflammatory immune mediators that are essential in shaping adaptive immune responses. (
  • ISG54 and viperin), PRRs, and interferon regulatory factors (IRFs), that can exert direct antiviral effects or amplify the antiviral response, thereby limiting viral replication [ 10 ]. (
  • MA also plays a role in the incorporation of the viral envelope (Env) glycoproteins and can influence particle infectivity post-maturation and post-entry. (
  • An often applied method to extinguish viral infectivity is the use of mutagenic drugs that increase the replication error rate of the viral genome. (
  • VIF Viral infectivity factor, a basic protein typically 23 kD. (
  • Promotes the infectivity but not the production of viral particles. (
  • This approach allowed for rapid in situ purification of virions and increased particle density that were instrumental for cryo-EM and cryoelectron tomography (cryo-ET). (
  • The matrix (MA) domain of the human immunodeficiency virus (HIV) 1 Gag is responsible for Gag targeting to the plasma membrane where virions assemble. (
  • Additionally, the 29KE/31KE MA mutant displays a defect in proteolytic cleavage of the murine leukemia virus Env cytoplasmic tail in pseudotyped virions. (
  • 14. Viral Genetics Viruses grow rapidly, there are usually a large number of progeny virions per cell. (
  • An antiretroviral agent that inhibits viral replication by disrupting late Gag processing, which is required for the structural rearrangement of viral maturation, a key step in the maturation of viral particles into mature, infectious virions. (
  • Quantitative analysis of reverse transcription products indicated that the levels of early cDNA products of the GAPDH-packaging-defective virus were higher than those of the control virus owing to the higher packaging efficiencies of LysRS and tRNA Lys3 into the virions rather than the GAPDH-dependent negative allosteric modulation for RT. (
  • Chronic neurological disease with distemper is associated with viral persistence. (
  • An additional aim is to decipher the role of T cell immune responses in order to further unravel the mechanism of HCV viral persistence. (
  • Younger JS, Preble OT (1980) Viral persistence: Evolution of viral populations. (
  • However, the particles are not infectious at the moment of release: they must undergo an extracellular maturation event before they are competent to infect a new host cell. (
  • R5 HIV-1 was mixed with the indicated concentrations of SE, incubated for the various time periods, and 20 μl of the virus stocks was used to infect 280 μl TZM-bl cell cultures in triplicates. (
  • There are some examples of viruses with two-hit kinetics: in other words, two different types of viral particles must infect a cell to initiate the infectious cycle. (
  • These viruses usually infect mammals, rodents, and birds, but only few coronaviruses adapted to humans. (
  • Since the total molecular mass (11.1 × 10 6 daltons) of these messengers is about twice that of the viral genome, sequence homologies must exist between the mRNAs. (
  • Understanding these interactions could elucidate molecular events essential for proper viral factory activity and could implicate new ways of treating viruses that form viral factories. (
  • Holland was also a central figure in applying molecular biology approaches to the study of viruses. (
  • Indeed, using novel, quantitative experimental approaches, Holland and his co-workers greatly advanced our understanding of the molecular mechanisms that have generated genetic diversity among RNA viruses and, ultimately, among living organisms in general. (
  • Viral-derived vectors are the most promising gene transfer tools due to the fact that viruses are naturally occurring molecular devices that have evolved to ensure targeted gene delivery and efficient expression in most cell types. (
  • Presented at the workshop on molecular and pathogenetic aspects of measles virus, 9. (
  • Molecular cloning and sequencing of the HBV genome led to the redefinition of the three HBV antigens as viral gene products endowed with specific functions in viral life cycle [for an in-depth review on the molecular biology of HBV, see ref. 13].The HBcAg and HBeAg are alternative translation products of the core gene, with HBeAg translation requiring an upstream precore region ATG codon (Fig. 2 ). (
  • In order to begin to understand the molecular basis of virus-induced disease, it is important to locate virus and viral genetic material within an infected host. (
  • Fujinami RS, Oldstone MBA (1980) Alterations in expression of measles virus polypeptides by antibody: Molecular events in antibody-induced antigenic mod-ulation. (
  • Shaw GM, Hahn BH, Arya SK, Groopman JE, Gallo RC, Wong-Staal F (1984) Molecular characterization of human T-cell leukemia (lymphotropic) virus type III in the acquired immune deficiency syndrome. (
  • This in vitro culturing system allows the study of viral replication and will facilitate the molecular dissection of important aspects of the MCPyV lifecycle. (
  • In addition, clones that made particles lacking reverse transcriptase were found, and these did not synthesize the reverse transcriptase precursor Pr180^(gag-pol). (
  • Reciprocally, virus-host recombination may also result in the integration of a piece of the host genome into a viral genome, supporting the idea that viruses may be efficient vectors of horizontal transfer of genetic material between species ( Gilbert and Cordaux 2017 ). (
  • The ability to prepare clonal virus stocks was an essential development that permitted genetic analysis of viruses. (
  • There is, therefore, more chance of mutations occurring over a short time period Viruses undergo genetic change by several mechanisms Genetic drift: where individual bases in the DNA or RNA mutate to other bases Antigenic shift: where there is a major change in the genome of the virus. (
  • High-Frequency Homologous Virus Genetic Recombination. (
  • 80 In other words, the finding of a viral genome (DNA) or even of RNA, antigens and antibodies to them, is not proof of the presence of infectious particles. (
  • were also strongly positive when assayed for viral antigens. (
  • Brahic M, Haase AT, Cash E (1984) Simultaneous in situ detection of viral RNA and antigens. (
  • Like all replication-incompetent vectors and viruses, viral particles can only be constructed if missing functions are superseded. (
  • Reichler MR, Bruden D, Thomas H. Ebola Patient Virus Cycle Threshold and Risk of Household Transmission of Ebola Virus external icon . (
  • Non-segmented negative strand (NNS) RNA viruses belonging to the order Mononegavirales are highly diversified eukaryotic viruses including significant human pathogens, such as rabies, measles, Nipah, and Ebola. (
  • Ebola virus (EBOV), isolate Makona, was the causative agent of the West African epidemic devastating predominantly Guinea, Liberia and Sierra Leone from 2013-2016. (
  • Ebola hemorrhagic fever (EHF), now also known as Ebola virus disease, is a fast-progressing, highly lethal zoonosis that, if not contained, poses a threat to global public health. (
  • Given the increasing urbanization of Africa and the globalization of air traffic, measures need to be put in place to control the next emergence of Ebola virus (EBOV). (
  • Mariana González Hernández is interested in host cell interactions of Ebola virus. (
  • Therefore, the tetracistronic trVLP assay represents the most comprehensive lifecycle modeling system available for Ebola viruses, and has tremendous potential for use in investigating the biology of Ebola viruses in future. (
  • Additionally, the abundance of viral variants within a host, as well as the impact of viral mutations on amino acid encoding and predicted protein function, determined whether intrahost variants were observed at the interhost level in circulating Nicaraguan DENV-2 populations, strongly suggestive of purifying selection across transmission events. (
  • Elucidating the mechanism by which compensatory mutations rescue an HIV-1 matrix mutant defective for gag membrane targeting and envelope glycoprotein incorporation. (
  • Here we examine the properties of 29KE/31KE by analyzing compensatory mutations obtained by a viral adaptation strategy. (
  • Most of these proviral sequences are defective due to multiple mutations or deletions. (
  • Our findings elucidate the mechanism whereby an MA mutant defective in PI(4,5)P2 binding can be rescued and highlight the ability of MA to influence Env glycoprotein function. (
  • ENV Viral glycoproteins produced as a precursor (gp160), which is processed to give a noncovalent complex of the external glycoprotein gp120 and the transmembrane glycoprotein gp41. (
  • Enveloped virus entry is initiated by binding to surface receptors/coreceptors followed by trafficking to specific entry sites where viruses encounter a milieu that provides for activation of their fusion machine, the viral envelope glycoprotein (Env). (
  • Single-use purification of cell culture-based virus particles by steric exclusion chromatography. (
  • Plaque purification is used extensively in virology to establish clonal virus stocks. (
  • A growing level of information supports recombinant viral vector usage as a means of vaccination. (
  • Stable Delivery of Physiologic Levels of Recombinant Erythropoietin to the Systemic Circulation by Intramuscular Injection of Replication-Defective Adenovirus", Basic Science (1994) 90(4):1-3. (
  • This white paper details how AccuPlex recombinant virus technology enables replication-defective virus particles that are commutable in any sample matrix and closely mimic pathogenic virus found in clinical samples. (
  • Alternatively, chimeric viral-vector systems that combine advantageous properties of two or more viral systems are also being explored. (
  • The choice of the appropriate viral vector for a specific gene transfer application necessitates careful consideration of several parameters - including stability constraints and production processes, the need for either transient or long-term expression, as well as the regulation of transgene expression. (
  • Viral vector systems that have been studied the most extensively in vaccinology are adenovirus vectors and poxvirus vectors. (
  • Pseudotyping is combining a virus or a part of a virus (vector) with a foreign viral envelope protein. (
  • Conversely, knockdown of the small brown planthopper CCR4 inhibited viral accumulation in the insect vector. (
  • 13. The method of claim 2 , wherein said viral vector is an adenoviral vector. (
  • Each viral vector system is characterized by an inherent set of properties that affect its suitability for gene therapy or other specific applications. (
  • In conclusion, there is still a tremendous amount of work to be done in viral vector research. (
  • New kinds of viruses, such as the lentiviruses (a more efficient and safer gene delivery vector) were created. (
  • The invention also concerns a vector comprising said nucleotide sequence, a viral particle generated from this vector, a cell comprising this vector or infected by the viral particle, their therapeutic use and a pharmaceutical composition containing them. (
  • 2. The vector according to claim 1 , wherein said vector is a plasmid vector or a viral vector selected from the group consisting of a poxviral vector, an adenoviral vector, a baculoviral vector, a herpesviral vector, an adeno-associated viral vector and a retroviral vector. (
  • The term retroviral vector is used for a vector based on murine leukaemia virus. (
  • The term lentiviral vector is used for a vector based on human immunodeficiency virus type 1. (
  • From virus to vector. (
  • Above is shown a typical vector design carrying a gene‐of‐interest (GOI) with viral cis ‐elements indicated (light green). (
  • b) Transfer vector harbouring an internal heterologous promoter in addition to the viral LTR promoter. (
  • 6 . The isolated polynucleotide of claim 3 wherein said polynucleotide comprises part of an expression vector, a viral genome, or a liposome. (
  • A 19-kD phosphoprotein, localized primarily in the nucleolus/nucleus, Rev acts by binding to RRE and promoting the nuclear export, stabilization, and utilization of the viral mRNAs containing RRE. (
  • Homologous Interference by Defective Virus Particles 10. (
  • When co-occurring with their parent, disease-causing viruses, DIPs act as parasites by stealing the very essential elements they lack. (
  • These DIPs will interfere in replication of the virus because they are reproduced at the expense of a standard viral particle. (
  • In some cases, the virus was also effective against metastases - it either eliminated the secondary tumor or inhibited its development. (
  • Although particle production was observed in some tumor cell lines, to date no infectious HERV-K has been described. (
  • We hypothesized that the differences in adenoviral replication between ovarian cancer cell lines and patient tumor samples are the result of a block in viral RNA transcription. (
  • In this article, we emphasize the similarity between EVs and viruses, in particular retroviruses. (
  • The particles turned out to be retroviruses, a viral family that includes the AIDS virus. (
  • As the AIDS virus so tragically confirms, most retroviruses have a knack for suppressing a host's immune system. (
  • During viral maturation, the Gag polyprotein is always cleaved into at least three cleavage products, termed (from N to C terminus) matrix (MA), capsid (CA), and nucleocapsid (NC) ( 43 ). (
  • APMV particles are characterized by an up to 700 nm large capsid (Figure 1A ), which is well above the resolution of a simple light microscope. (
  • PA-457) prevent virus maturation by interrupting the conversion of the capsid precursor (p25) to a mature capsid protein (p24), resulting in the formation of defective, noninfectious virus particles. (
  • Despite these defects, each clone released particles of type C morphology, suggesting that gag gene function alone may be sufficient for particle production. (
  • Virus Particle Morphology and Morphogenesis. (
  • In both of these mutants, the dimeric viral RNA had undergone the stabilization normally associated with maturation, suggesting that this change may depend upon the separation of CA from NC. (
  • Within the quasispecies, positive (Darwinian) selection implies that one or more members of the quasispecies are better suited to a given environment while negative selection eliminates unfit variants In the absence of drug pressure, resistant mutants tend to disappear from the dominant quasispecies as they are outgrown by the fitter wild-type virus. (
  • For the research, she isolated a rabies type of virus which produced mutant strains interfering with viral growth. (
  • Background: In preclinical and phase 2 studies, adefovir dipivoxil demonstrated potent activity against hepatitis B virus (HBV), including lamivudine-resistant strains. (
  • One example is the poxviral/retroviral chimeric construct that allows cytoplasmic production of transducing defective retroviral particles. (
  • By counting the number of plaques, the virus titer can be calculated in PFU per ml. (
  • Extracellular vesicles and viruses: Are they close relatives? (
  • The results showed that CAMs blocked extracellular HBV RNA with efficiencies similar to those with which they blocked pregenomic RNA (pgRNA) encapsidation, HBV DNA replication, and Dane particle production. (
  • Nucleos(t)ide analogs inhibited viral replication and virion production but not encapsidation or production of extracellular HBV RNA. (
  • Profiling of HBV RNA from both culture supernatants and patient serum showed that extracellular viral RNA consisted of pgRNA and spliced pgRNA variants with an internal deletion(s) but still retained the sequences at both the 5′ and 3′ ends. (
  • 26:705-713, 1979), but no permissive cell type for growth of the virus in vitro has been identified. (
  • Biodegradable Cationic Polymers (BCPs) and mimicks of virus nuclear targeting peptides (VIPs), once chemically attached to nucleic acids, can lead this exogenous material to passively cross the plasmic membrane. (
  • Exognenous nucleic sequences of interest can now piggy-back on dompted viruses and efficiently find their way to the inside of the cell once prohibited. (
  • Haase AT, Brahic M, Stowring L (1984) Detection of viral nucleic acids by in situ hybridization. (
  • This way, if a viral production is required, the replicative elements must be provided by the host cell line (usually 293T) upon transfection with dedicated vectors bearing the packaging elements of the virus. (
  • In fact, it is now clear that moderately high levels of virus production occur at all stages of disease in most HIV-infected individuals. (
  • Measurement of the decay in viremia during the weeks to months after initiation of potent antiretroviral therapy allowed estimation of the daily virus production (up to 10 billion viral particles daily) and of the virus turnover, in which the virus half-life is estimated to be less than 6 hours. (
  • The production of large progeny numbers affected by high mutation rates is a ubiquitous strategy of viruses, as it promotes quick adaptation and survival to changing environments. (
  • Next-generation production platforms for viral therapies. (
  • As a result, our ability to develop specific therapeutic protocols is limited, and the design of control strategies that cause viral extinction represents an important challenge. (
  • Viruses produced in the absence of ORF75A were characterized by an increase in the ratio of particles to PFU. (
  • In the absence of Vif, the produced viral particles are defective, while the cell-to-cell transmission of virus is not affected significantly. (
  • In this figure, the number of plaques produced by a virus with one-hit kinetics or two-hit kinetics is plotted versus the relative concentration of the virus. (
  • Most viral vectors are usually injected in blood, tumors or muscle tissue, but adenoviral and adeno-associated vectors can also be delivered via inhalation. (
  • In this particular case, the KAN-1-induced defective RNA-encoded protein PB2∆ enhances the overwhelming immune response characteristic for highly pathogenic H5N1 viruses, leading to a more severe phenotype in vivo. (
  • These high levels of HIV replication fall abruptly with the development of an immune response to the virus, now thought to be mediated largely by the emergence of cytotoxic CD8+ lymphocytes, rather than by development of neutralizing antibody. (
  • One of the first barriers that viral vectors have to bypass in the human organism is the immune response. (
  • Four days later the patient was dead from multiple organ failure, and speculation centered on the possibility that the immense and sudden injection of the virus caused an overwhelming immune response. (
  • Virology, as a science, having passed only recently through its descriptive phase of naming and num- bering, has probably reached that stage at which relatively few new-truly new-viruses will be discovered. (
  • A proof of concept of viral gene therapy has been demonstrated by a large number of animal studies. (
  • Viral vectors can be applied in gene therapy in order to treat different diseases such as cancer, metabolic diseases, heart defects and neurodegenerative disorders. (
  • Recent discovery that specific serotypes of adeno-associated virus gene delivery vectors have the ability to cross the blood-brain barrier upon intravenous administration has led to the possibility of perinatal gene therapy. (
  • In: Vos J. Viruses in Human Gene Therapy. (
  • Viral Vectors for Gene Therapy: Methods and Protocols. (
  • The idea of gene therapy, which quickly captured the public imagination, was fueled by its appealingly straightforward approach and what Friedmann has described as its "obvious correctness": Disarm a potentially pathogenic virus to make it benign. (
  • It is apparent that the murine leukemia virus genome is often mutated by spontaneous processes generating a wide range of phenotypes. (
  • A plethora of such non-viral systems incorporate parts of viral vectors in order to escalate the efficiency of gene delivery or expression. (
  • In addition, expression of a spliced env mRNA was found in human breast tumors but no data are available on virus protein expression ( 14 ). (
  • In contrast to the promoting effect of ATM on the lytic EBV reactivation in normoxia, ATM inhibited lytic EBV gene expression and decreased the EBV viral load in the prescence of hypoxia-induced DNA damage. (
  • One of two essential viral regulatory factors (Tat and Rev) for HIV gene expression. (
  • Omission of either the M or G protein expression resulted in no DI particle budding. (
  • Rice GPA, Schrier RD, Oldstone MBA (1984) Cytomegalovirus infects human lymphocytes and monocytes: Virus expression is restricted to immediate-early gene products. (
  • However, the viral factor(s) involved in NKG2D ligand expression still remains undefined. (
  • Here, we demonstrate that transfection of recircularized MCVSyn DNA into some human cell lines recapitulates efficient replication of the viral genome, early and late gene expression together with virus particle formation. (
  • Circulating infectious virus titers are much lower than plasma HIV RNA levels, suggesting that the majority of virus particles are defective. (
  • This conclusion can be reached by studying the relationship between the number of infectious virus particles and the plaque count. (
  • However, serial transmission of infectious virus was not observed. (
  • Concurrent with stimulating signaling, TRIM21 recruits p97/VCP, a AAA+ ATPase with segregase and unfoldase activity, and the proteasome, resulting in premature disassembly and degradation of viral capsids. (
  • This profound prophylactic effect of defective T particles is due to homologous autointerference since it is serotype-specific and interferon is not induced. (
  • When a single virus particle can form a plaque, the viral progeny within the plaque are clones. (
  • This can be in a form of a helper virus, but a single helper plasmid encoding for a full-length defective helper virus genome can also be utilized. (
  • The oscillation in titers occurs because the DI particles reach sufficiently high numbers that they interfere substantially with the 'helper' virus. (
  • Since the DI particle needs the helper virus, the result is that DI particle titers decline, until helper virus titers recover. (
  • The coronaviruses are a family of viruses that includes a series of very different pathogens. (
  • After the assembled virion is released from the cell, Gag is cleaved at several sites by the viral protease (PR). (
  • The cleavages catalyzed by PR bring about a wide variety of physical changes in the particle, collectively termed maturation, and convert the particle into an infectious virion. (
  • VPR Vpr (viral protein R) is a 96-amino acid (14-kD) protein, which is incorporated into the virion. (
  • Among the cis ‐acting control sequences are the LTR (long terminal repeat) that harbours control regions for transcription, reverse transcription, and integration and the packaging signal (ψ) for encapsidation of RNA into viral particles. (
  • An amplicon plasmid ( Fig. 2A ) is a standard Escherichia coli plasmid carrying one origin of virus replication (OriS) and one packaging signal (pac) from HSV-1, in addition to the transgenic sequences of interest (Vlazny & Frenkel 1981, Spaete & Frenkel 1985, Deiss et al. (
  • Puga A, Rosenthal JD, Openshaw H, Notkins AL (1978) Herpes simplex virus DNA and mRNA sequences in acutely and chronically infected trigeminal ganglia of mice. (