Bacterial proteins that are used by BACTERIOPHAGES to incorporate their DNA into the DNA of the "host" bacteria. They are DNA-binding proteins that function in genetic recombination as well as in transcriptional and translational regulation.

The interactions between a host and a pathogen, usually resulting in disease.

An integration host factor that was originally identified as a bacterial protein required for the integration of bacteriophage Q beta (ALLOLEVIVIRUS). Its cellular function may be to regulate mRNA stability and processing in that it binds tightly to poly(A) RNA and interferes with ribosome binding.

A broad category of endogenous cellular factors that are used by VIRUSES for essential functions such as VIRUS REPLICATION. Many host-derived factors play normal cellular roles in non-infected cells.

Proteins found in any species of bacterium.

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.

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 species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

The properties of a pathogen that makes it capable of infecting one or more specific hosts. The pathogen can include PARASITES as well as VIRUSES; BACTERIA; FUNGI; or PLANTS.

The relationship between an invertebrate and another organism (the host), one of which lives at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically.

A temperate inducible phage and type species of the genus lambda-like viruses, in the family SIPHOVIRIDAE. Its natural host is E. coli K12. Its VIRION contains linear double-stranded DNA with single-stranded 12-base 5' sticky ends. The DNA circularizes on infection.

Proteins found in any species of virus.

Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.

Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.

Deoxyribonucleic acid that makes up the genetic material of bacteria.

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.

Established cell cultures that have the potential to propagate indefinitely.

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.

Ribonucleic acid that makes up the genetic material of viruses.

Proteins obtained from ESCHERICHIA COLI.

A temperate coliphage, in the genus Mu-like viruses, family MYOVIRIDAE, composed of a linear, double-stranded molecule of DNA, which is able to insert itself randomly at any point on the host chromosome. It frequently causes a mutation by interrupting the continuity of the bacterial OPERON at the site of insertion.

An enzyme that catalyzes the replication of the RNA of coliphage Q beta. EC 2.7.7.-.

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.

Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: TOXINS, BIOLOGICAL and surface adhesion molecules that effect the ability of the microorganism to invade and colonize a host. (From Davis et al., Microbiology, 4th ed. p486)

DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.

Deoxyribonucleic acid that makes up the genetic material of viruses.

The type species of LENTIVIRUS and the etiologic agent of AIDS. It is characterized by its cytopathic effect and affinity for the T4-lymphocyte.

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.

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.

The parts of a macromolecule that directly participate in its specific combination with another molecule.

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.

Recombinases that insert exogenous DNA into the host genome. Examples include proteins encoded by the POL GENE of RETROVIRIDAE and also by temperate BACTERIOPHAGES, the best known being BACTERIOPHAGE LAMBDA.

The functional hereditary units of BACTERIA.

The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.

Specific loci on both the bacterial DNA (attB) and the phage DNA (attP) which delineate the sites where recombination takes place between them, as the phage DNA becomes integrated (inserted) into the BACTERIAL DNA during LYSOGENY.

The capacity of a normal organism to remain unaffected by microorganisms and their toxins. It results from the presence of naturally occurring ANTI-INFECTIVE AGENTS, constitutional factors such as BODY TEMPERATURE and immediate acting immune cells such as NATURAL KILLER CELLS.

An enzyme that catalyses RNA-template-directed extension of the 3'- end of an RNA strand by one nucleotide at a time, and can initiate a chain de novo. (Enzyme Nomenclature, 1992, p293)

A DNA-directed RNA polymerase found in BACTERIA. It is a holoenzyme that consists of multiple subunits including sigma factor 54.

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.

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.

Any of the processes by which cytoplasmic factors influence the differential control of gene action in viruses.

A genus of FLAVIVIRIDAE causing parenterally-transmitted HEPATITIS C which is associated with transfusions and drug abuse. Hepatitis C virus is the type species.

Viruses whose host is Escherichia coli.

The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.

A gene silencing phenomenon whereby specific dsRNAs (RNA, DOUBLE-STRANDED) trigger the degradation of homologous mRNA (RNA, MESSENGER). The specific dsRNAs are processed into SMALL INTERFERING RNA (siRNA) which serves as a guide for cleavage of the homologous mRNA in the RNA-INDUCED SILENCING COMPLEX. DNA METHYLATION may also be triggered during this process.

Any DNA sequence capable of independent replication or a molecule that possesses a REPLICATION ORIGIN and which is therefore potentially capable of being replicated in a suitable cell. (Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)

A bacteriophage genus of the family LEVIVIRIDAE, whose viruses contain the longer version of the genome and have no separate cell lysis gene.

Enzymes that catalyze the incorporation of deoxyribonucleotides into a chain of DNA. EC 2.7.7.-.

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.

Enzymes that recombine DNA segments by a process which involves the formation of a synapse between two DNA helices, the cleavage of single strands from each DNA helix and the ligation of a DNA strand from one DNA helix to the other. The resulting DNA structure is called a Holliday junction which can be resolved by DNA REPLICATION or by HOLLIDAY JUNCTION RESOLVASES.

Bacteriophages whose genetic material is RNA, which is single-stranded in all except the Pseudomonas phage phi 6 (BACTERIOPHAGE PHI 6). All RNA phages infect their host bacteria via the host's surface pili. Some frequently encountered RNA phages are: BF23, F2, R17, fr, PhiCb5, PhiCb12r, PhiCb8r, PhiCb23r, 7s, PP7, Q beta phage, MS2 phage, and BACTERIOPHAGE PHI 6.

A species of gram-negative, aerobic bacteria isolated from soil and water as well as clinical specimens. Occasionally it is an opportunistic pathogen.

The complete genetic complement contained in a DNA or RNA molecule in a virus.

Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.

Viruses whose genetic material is RNA.

Proteins encoded by a VIRAL GENOME that are produced in the organisms they infect, but not packaged into the VIRUS PARTICLES. Some of these proteins may play roles within the infected cell during VIRUS REPLICATION or act in regulation of virus replication or VIRUS ASSEMBLY.

A family of hepatotropic DNA viruses which contains double-stranded DNA genomes and causes hepatitis in humans and animals. There are two genera: AVIHEPADNAVIRUS and ORTHOHEPADNAVIRUS. Hepadnaviruses include HEPATITIS B VIRUS, duck hepatitis B virus (HEPATITIS B VIRUS, DUCK), heron hepatitis B virus, ground squirrel hepatitis virus, and woodchuck hepatitis B virus (HEPATITIS B VIRUS, WOODCHUCK).

A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.

A genus of plant viruses that infects ANGIOSPERMS. Transmission occurs mechanically and through soil, with one species transmitted via a fungal vector. The type species is Tomato bushy stunt virus.

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.

The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.

The relationships of groups of organisms as reflected by their genetic makeup.

Diseases of plants.

A method for determining the sequence specificity of DNA-binding proteins. DNA footprinting utilizes a DNA damaging agent (either a chemical reagent or a nuclease) which cleaves DNA at every base pair. DNA cleavage is inhibited where the ligand binds to DNA. (from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)

Enzymes that catalyze DNA template-directed extension of the 3'-end of an RNA strand one nucleotide at a time. They can initiate a chain de novo. In eukaryotes, three forms of the enzyme have been distinguished on the basis of sensitivity to alpha-amanitin, and the type of RNA synthesized. (From Enzyme Nomenclature, 1992).

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.

The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)

Transport proteins that carry specific substances in the blood or across cell membranes.

Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.

A constitution or condition of the body which makes the tissues react in special ways to certain extrinsic stimuli and thus tends to make the individual more than usually susceptible to certain diseases.

In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.

The phenomenon by which a temperate phage incorporates itself into the DNA of a bacterial host, establishing a kind of symbiotic relation between PROPHAGE and bacterium which results in the perpetuation of the prophage in all the descendants of the bacterium. Upon induction (VIRUS ACTIVATION) by various agents, such as ultraviolet radiation, the phage is released, which then becomes virulent and lyses the bacterium.

Methods used by pathogenic organisms to evade a host's immune system.

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.

A species of ENTEROVIRUS which is the causal agent of POLIOMYELITIS in humans. Three serotypes (strains) exist. Transmission is by the fecal-oral route, pharyngeal secretions, or mechanical vector (flies). Vaccines with both inactivated and live attenuated virus have proven effective in immunizing against the infection.

A plant genus of the family SOLANACEAE. Members contain NICOTINE and other biologically active chemicals; its dried leaves are used for SMOKING.

A highly abundant DNA binding protein whose expression is strongly correlated with the growth phase of bacteria. The protein plays a role in regulating DNA topology and activation of RIBOSOMAL RNA transcription. It was originally identified as a factor required for inversion stimulation by the Hin recombinase of SALMONELLA and Gin site-specific recombinase of BACTERIOPHAGE MU.

Inbred BALB/c mice are a strain of laboratory mice that have been selectively bred to be genetically identical to each other, making them useful for scientific research and experiments due to their consistent genetic background and predictable responses to various stimuli or treatments.

Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.

Enzymes that catalyze the template-directed incorporation of ribonucleotides into an RNA chain. EC 2.7.7.-.

The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.

The relationship between two different species of organisms that are interdependent; each gains benefits from the other or a relationship between different species where both of the organisms in question benefit from the presence of the other.

Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

Viruses whose host is one or more Mycobacterium species. They include both temperate and virulent types.

Genotypic differences observed among individuals in a population.

The specificity of a virus for infecting a particular type of cell or tissue.

The functional hereditary units of VIRUSES.

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.

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.

Small double-stranded, non-protein coding RNAs (21-31 nucleotides) involved in GENE SILENCING functions, especially RNA INTERFERENCE (RNAi). Endogenously, siRNAs are generated from dsRNAs (RNA, DOUBLE-STRANDED) by the same ribonuclease, Dicer, that generates miRNAs (MICRORNAS). The perfect match of the siRNAs' antisense strand to their target RNAs mediates RNAi by siRNA-guided RNA cleavage. siRNAs fall into different classes including trans-acting siRNA (tasiRNA), repeat-associated RNA (rasiRNA), small-scan RNA (scnRNA), and Piwi protein-interacting RNA (piRNA) and have different specific gene silencing functions.

The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.

A protein which is a subunit of RNA polymerase. It effects initiation of specific RNA chains from DNA.

An enzyme capable of hydrolyzing highly polymerized DNA by splitting phosphodiester linkages, preferentially adjacent to a pyrimidine nucleotide. This catalyzes endonucleolytic cleavage of DNA yielding 5'-phosphodi- and oligonucleotide end-products. The enzyme has a preference for double-stranded DNA.

Includes the spectrum of human immunodeficiency virus infections that range from asymptomatic seropositivity, thru AIDS-related complex (ARC), to acquired immunodeficiency syndrome (AIDS).

Viruses whose hosts are bacterial cells.

The process by which a DNA molecule is duplicated.

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.

The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.

Proteins that bind to RNA molecules. Included here are RIBONUCLEOPROTEINS and other proteins whose function is to bind specifically to RNA.

Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.

The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.

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.

Proteins synthesized by HUMAN IMMUNODEFICIENCY VIRUSES such as the HIV-1 and HIV-2.

A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.

Physicochemical property of fimbriated (FIMBRIAE, BACTERIAL) and non-fimbriated bacteria of attaching to cells, tissue, and nonbiological surfaces. It is a factor in bacterial colonization and pathogenicity.

Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.

The assembly of VIRAL STRUCTURAL PROTEINS and nucleic acid (VIRAL DNA or VIRAL RNA) to form a VIRUS PARTICLE.

Viral proteins that facilitate the movement of viruses between plant cells by means of PLASMODESMATA, channels that traverse the plant cell walls.

Mutagenesis where the mutation is caused by the introduction of foreign DNA sequences into a gene or extragenic sequence. This may occur spontaneously in vivo or be experimentally induced in vivo or in vitro. Proviral DNA insertions into or adjacent to a cellular proto-oncogene can interrupt GENETIC TRANSLATION of the coding sequences or interfere with recognition of regulatory elements and cause unregulated expression of the proto-oncogene resulting in tumor formation.

Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.

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.

Use of restriction endonucleases to analyze and generate a physical map of genomes, genes, or other segments of DNA.

One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.

Methods for determining interaction between PROTEINS.

Elements of limited time intervals, contributing to particular results or situations.

The type species of the genus INFLUENZAVIRUS A that causes influenza and other diseases in humans and animals. Antigenic variation occurs frequently between strains, allowing classification into subtypes and variants. Transmission is usually by aerosol (human and most non-aquatic hosts) or waterborne (ducks). Infected birds shed the virus in their saliva, nasal secretions, and feces.

Proteins isolated from the outer membrane of Gram-negative bacteria.

The determination of the pattern of genes expressed at the level of GENETIC TRANSCRIPTION, under specific circumstances or in a specific cell.

Interruption or suppression of the expression of a gene at transcriptional or translational levels.

Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.

The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.

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.

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.

A bacterium which is one of the etiologic agents of bacillary dysentery (DYSENTERY, BACILLARY) and sometimes of infantile gastroenteritis.

The rate dynamics in chemical or physical systems.

Screening techniques first developed in yeast to identify genes encoding interacting proteins. Variations are used to evaluate interplay between proteins and other molecules. Two-hybrid techniques refer to analysis for protein-protein interactions, one-hybrid for DNA-protein interactions, three-hybrid interactions for RNA-protein interactions or ligand-based interactions. Reverse n-hybrid techniques refer to analysis for mutations or other small molecules that dissociate known interactions.

A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.

The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.

Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner.

Circular duplex DNA isolated from viruses, bacteria and mitochondria in supercoiled or supertwisted form. This superhelical DNA is endowed with free energy. During transcription, the magnitude of RNA initiation is proportional to the DNA superhelicity.

The type species of TOBAMOVIRUS which causes mosaic disease of tobacco. Transmission occurs by mechanical inoculation.

Proteins found mainly in icosahedral DNA and RNA viruses. They consist of proteins directly associated with the nucleic acid inside the NUCLEOCAPSID.

A parasexual process in BACTERIA; ALGAE; FUNGI; and ciliate EUKARYOTA for achieving exchange of chromosome material during fusion of two cells. In bacteria, this is a uni-directional transfer of genetic material; in protozoa it is a bi-directional exchange. In algae and fungi, it is a form of sexual reproduction, with the union of male and female gametes.

Nucleic acid sequences involved in regulating the expression of genes.

Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.

An enzyme that catalyzes the deamination of cytidine, forming uridine. EC 3.5.4.5.

Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins.

The quantity of measurable virus in a body fluid. Change in viral load, measured in plasma, is sometimes used as a SURROGATE MARKER in disease progression.

Proteins prepared by recombinant DNA technology.

A CELL LINE derived from the kidney of the African green (vervet) monkey, (CERCOPITHECUS AETHIOPS) used primarily in virus replication studies and plaque assays.

A large family of RNA helicases that share a common protein motif with the single letter amino acid sequence D-E-A-D (Asp-Glu-Ala-Asp). In addition to RNA helicase activity, members of the DEAD-box family participate in other aspects of RNA metabolism and regulation of RNA function.

A critical subpopulation of T-lymphocytes involved in the induction of most immunological functions. The HIV virus has selective tropism for the T4 cell which expresses the CD4 phenotypic marker, a receptor for HIV. In fact, the key element in the profound immunosuppression seen in HIV infection is the depletion of this subset of T-lymphocytes.

Rapid methods of measuring the effects of an agent in a biological or chemical assay. The assay usually involves some form of automation or a way to conduct multiple assays at the same time using sample arrays.

Persons who have experienced prolonged survival of HIV infection. This includes the full spectrum of untreated, HIV-infected long-term asymptomatics to those with AIDS who have survived due to successful treatment.

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.

The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.

A group of uridine ribonucleotides in which the phosphate residues of each uridine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.

Tetraspanin proteins that are involved in a variety of cellular functions including BASEMENT MEMBRANE assembly, and in the formation of a molecular complexes on the surface of LYMPHOCYTES.

Membrane-bound cytoplasmic vesicles formed by invagination of phagocytized material. They fuse with lysosomes to form phagolysosomes in which the hydrolytic enzymes of the lysosome digest the phagocytized material.

A transcriptional regulator in prokaryotes which, when activated by binding cyclic AMP, acts at several promoters. Cyclic AMP receptor protein was originally identified as a catabolite gene activator protein. It was subsequently shown to regulate several functions unrelated to catabolism, and to be both a negative and a positive regulator of transcription. Cell surface cyclic AMP receptors are not included (CYCLIC AMP RECEPTORS), nor are the eukaryotic cytoplasmic cyclic AMP receptor proteins, which are the regulatory subunits of CYCLIC AMP-DEPENDENT PROTEIN KINASES.

Proteins that catalyze the unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening. In addition DNA helicases are DNA-dependent ATPases that harness the free energy of ATP hydrolysis to translocate DNA strands.

Proteins secreted by vertebrate cells in response to a wide variety of inducers. They confer resistance against many different viruses, inhibit proliferation of normal and malignant cells, impede multiplication of intracellular parasites, enhance macrophage and granulocyte phagocytosis, augment natural killer cell activity, and show several other immunomodulatory functions.

Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications.

A plasmid whose presence in the cell, either extrachromosomal or integrated into the BACTERIAL CHROMOSOME, determines the "sex" of the bacterium, host chromosome mobilization, transfer via conjugation (CONJUGATION, GENETIC) of genetic material, and the formation of SEX PILI.

A unique DNA sequence of a replicon at which DNA REPLICATION is initiated and proceeds bidirectionally or unidirectionally. It contains the sites where the first separation of the complementary strands occurs, a primer RNA is synthesized, and the switch from primer RNA to DNA synthesis takes place. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)

Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.

The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.

A group of enzymes that catalyzes the hydrolysis of terminal, non-reducing beta-D-galactose residues in beta-galactosides. Deficiency of beta-Galactosidase A1 may cause GANGLIOSIDOSIS, GM1.

The biosynthesis of DNA carried out on a template of RNA.

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.

Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.

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.

Proteins encoded by the VIF GENES of the HUMAN IMMUNODEFICIENCY VIRUS.

A circumscribed stable malformation of the skin and occasionally of the oral mucosa, which is not due to external causes and therefore presumed to be of hereditary origin.

Invertebrate organisms that live on or in another organism (the host), and benefit at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically.

Substances elaborated by bacteria that have antigenic activity.

A family of RNA viruses causing INFLUENZA and other diseases. There are five recognized genera: INFLUENZAVIRUS A; INFLUENZAVIRUS B; INFLUENZAVIRUS C; ISAVIRUS; and THOGOTOVIRUS.

Proteins encoded by the GAG GENE of the HUMAN IMMUNODEFICIENCY VIRUS.

An enzyme that catalyzes the conversion of phosphatidylinositol (PHOSPHATIDYLINOSITOLS) to phosphatidylinositol 4-phosphate, the first committed step in the biosynthesis of phosphatidylinositol 4,5-bisphosphate.

Any of numerous winged hymenopterous insects of social as well as solitary habits and having formidable stings.

Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.

Human immunodeficiency virus. A non-taxonomic and historical term referring to any of two species, specifically HIV-1 and/or HIV-2. Prior to 1986, this was called human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). From 1986-1990, it was an official species called HIV. Since 1991, HIV was no longer considered an official species name; the two species were designated HIV-1 and HIV-2.

The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (PHAGOCYTES).

A cell line generated from human embryonic kidney cells that were transformed with human adenovirus type 5.

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).

Complexes of RNA-binding proteins with ribonucleic acids (RNA).

A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation.

The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.

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.

Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.

A genus of plant viruses in the family FLEXIVIRIDAE, that cause mosaic and ringspot symptoms. Transmission occurs mechanically. Potato virus X is the type species.

The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.

Infections with bacteria of the species ESCHERICHIA COLI.

Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.

A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).

A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.

A general term for diseases produced by viruses.

Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.

Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.

A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.

A genus in the family FILOVIRIDAE consisting of several distinct species of Ebolavirus, each containing separate strains. These viruses cause outbreaks of a contagious, hemorrhagic disease (HEMORRHAGIC FEVER, EBOLA) in humans, usually with high mortality.

Any spaces or cavities within a cell. They may function in digestion, storage, secretion, or excretion.

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.

Proteins that form the CAPSID of VIRUSES.

Inbred C3H mice are a strain of laboratory mice that have been selectively bred to maintain a high degree of genetic uniformity and share specific genetic characteristics, including susceptibility to certain diseases, which makes them valuable for biomedical research purposes.

Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)

The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)

Deletion of sequences of nucleic acids from the genetic material of an individual.

A family of plant viruses where the VIRION possesses an unusual morphology consisting of a pair of isometric particles. Transmission occurs via leafhoppers or whitefly. Some viruses cause economically important diseases in cultivated plants. There are four genera: Mastrevirus, Curtovirus, Topocuvirus, and BEGOMOVIRUS.

The regulatory elements of an OPERON to which activators or repressors bind thereby effecting the transcription of GENES in the operon.

Genes whose expression is easily detectable and therefore used to study promoter activity at many positions in a target genome. In recombinant DNA technology, these genes may be attached to a promoter region of interest.