Vero Cells: A CELL LINE derived from the kidney of the African green (vervet) monkey, (CERCOPITHECUS AETHIOPS) used primarily in virus replication studies and plaque assays.Cercopithecus aethiops: 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.Diphtheria Toxin: An ADP-ribosylating polypeptide produced by CORYNEBACTERIUM DIPHTHERIAE that causes the signs and symptoms of DIPHTHERIA. It can be broken into two unequal domains: the smaller, catalytic A domain is the lethal moiety and contains MONO(ADP-RIBOSE) TRANSFERASES which transfers ADP RIBOSE to PEPTIDE ELONGATION FACTOR 2 thereby inhibiting protein synthesis; and the larger B domain that is needed for entry into cells.Virus Replication: 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.Cytopathogenic Effect, Viral: 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.Viral Plaque Assay: 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.Distemper Virus, Canine: A species of MORBILLIVIRUS causing distemper in dogs, wolves, foxes, raccoons, and ferrets. Pinnipeds have also been known to contract Canine distemper virus from contact with domestic dogs.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Haplorhini: 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).Herpesvirus 1, Human: 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.Shiga Toxin 1: A toxin produced by certain pathogenic strains of ESCHERICHIA COLI such as ESCHERICHIA COLI O157. It is closely related to SHIGA TOXIN produced by SHIGELLA DYSENTERIAE.Simplexvirus: A genus of the family HERPESVIRIDAE, subfamily ALPHAHERPESVIRINAE, consisting of herpes simplex-like viruses. The type species is HERPESVIRUS 1, HUMAN.Measles virus: The type species of MORBILLIVIRUS and the cause of the highly infectious human disease MEASLES, which affects mostly children.Viral Proteins: Proteins found in any species of virus.Serial Passage: Inoculation of a series of animals or in vitro tissue with an infectious bacterium or virus, as in VIRULENCE studies and the development of vaccines.Virus Cultivation: Process of growing viruses in live animals, plants, or cultured cells.Cytotoxins: Substances that are toxic to cells; they may be involved in immunity or may be contained in venoms. These are distinguished from CYTOSTATIC AGENTS in degree of effect. Some of them are used as CYTOTOXIC ANTIBIOTICS. The mechanism of action of many of these are as ALKYLATING AGENTS or MITOSIS MODULATORS.Dengue Virus: A species of the genus FLAVIVIRUS which causes an acute febrile and sometimes hemorrhagic disease in man. Dengue is mosquito-borne and four serotypes are known.Ricin: A protein phytotoxin from the seeds of Ricinus communis, the castor oil plant. It agglutinates cells, is proteolytic, and causes lethal inflammation and hemorrhage if taken internally.African Swine Fever Virus: The lone species of the genus Asfivirus. It infects domestic and wild pigs, warthogs, and bushpigs. Disease is endemic in domestic swine in many African countries and Sardinia. Soft ticks of the genus Ornithodoros are also infected and act as vectors.Bacterial Toxins: Toxic substances formed in or elaborated by bacteria; they are usually proteins with high molecular weight and antigenicity; some are used as antibiotics and some to skin test for the presence of or susceptibility to certain diseases.Shiga Toxin 2: A toxin produced by certain pathogenic strains of ESCHERICHIA COLI such as ESCHERICHIA COLI O157. It shares 50-60% homology with SHIGA TOXIN and SHIGA TOXIN 1.Shiga Toxins: A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; (RNA, RIBOSOMAL) with PEPTIDE ELONGATION FACTORS. They include SHIGA TOXIN which is produced by SHIGELLA DYSENTERIAE and a variety of shiga-like toxins that are produced by pathologic strains of ESCHERICHIA COLI such as ESCHERICHIA COLI O157.Arenaviridae: A family of RNA viruses naturally infecting rodents and consisting of one genus (ARENAVIRUS) with two groups: Old World Arenaviruses (ARENAVIRUSES, OLD WORLD) and New World Arenaviruses (ARENAVIRUSES, NEW WORLD). Infection in rodents is persistent and silent. Vertical transmission is through milk-, saliva-, or urine-borne routes. Horizontal transmission to humans, monkeys, and other animals is important.Reverse Genetics: The use of techniques that produce a functional MUTATION or an effect on GENE EXPRESSION of a specific gene of interest in order to identify the role or activity of the gene product of that gene.Molecular Sequence Data: 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.Iridoviridae: A family of large icosahedral DNA viruses infecting insects and poikilothermic vertebrates. Genera include IRIDOVIRUS; RANAVIRUS; Chloriridovirus; Megalocytivirus; and Lymphocystivirus.Viral Envelope Proteins: 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.Flavivirus: A genus of FLAVIVIRIDAE containing several subgroups and many species. Most are arboviruses transmitted by mosquitoes or ticks. The type species is YELLOW FEVER VIRUS.Distemper: A name for several highly contagious viral diseases of animals, especially canine distemper. In dogs, it is caused by the canine distemper virus (DISTEMPER VIRUS, CANINE). It is characterized by a diphasic fever, leukopenia, gastrointestinal and respiratory inflammation and sometimes, neurologic complications. In cats it is known as FELINE PANLEUKOPENIA.Antiviral Agents: 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.Encephalitis Viruses, Japanese: A subgroup of the genus FLAVIVIRUS which comprises a number of viral species that are the etiologic agents of human encephalitis in many different geographical regions. These include Japanese encephalitis virus (ENCEPHALITIS VIRUS, JAPANESE), St. Louis encephalitis virus (ENCEPHALITIS VIRUS, ST. LOUIS), Murray Valley encephalitis virus (ENCEPHALITIS VIRUS, MURRAY VALLEY), and WEST NILE VIRUS.Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.Plumbaginaceae: A plant family of the order Plumbaginales, subclass Caryophyllidae, class Magnoliopsida of shrubs and herbs. Some members contain ANTHOCYANINS and naphthaquinones.Genes, Viral: The functional hereditary units of VIRUSES.Bunyaviridae: A family of viruses, mainly arboviruses, consisting of a single strand of RNA. Virions are enveloped particles 90-120 nm diameter. The complete family contains over 300 members arranged in five genera: ORTHOBUNYAVIRUS; HANTAVIRUS; NAIROVIRUS; PHLEBOVIRUS; and TOSPOVIRUS.Enterotoxins: Substances that are toxic to the intestinal tract causing vomiting, diarrhea, etc.; most common enterotoxins are produced by bacteria.Neutralization Tests: 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).Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.Arboviruses: Arthropod-borne viruses. A non-taxonomic designation for viruses that can replicate in both vertebrate hosts and arthropod vectors. Included are some members of the following families: ARENAVIRIDAE; BUNYAVIRIDAE; REOVIRIDAE; TOGAVIRIDAE; and FLAVIVIRIDAE. (From Dictionary of Microbiology and Molecular Biology, 2nd ed)RNA, Viral: Ribonucleic acid that makes up the genetic material of viruses.Rubella virus: The type (and only) species of RUBIVIRUS causing acute infection in humans, primarily children and young adults. Humans are the only natural host. A live, attenuated vaccine is available for prophylaxis.Rickettsia: A genus of gram-negative, aerobic, rod-shaped bacteria often surrounded by a protein microcapsular layer and slime layer. The natural cycle of its organisms generally involves a vertebrate and an invertebrate host. Species of the genus are the etiological agents of human diseases, such as typhus.Chromolaena: A plant genus of the family ASTERACEAE. The common name of thoroughwort is also used for other plants including EUPATORIUM; CHROMOLAENA, Hebeclinium and Koanophyllon. Eupolin is the aqueous extract of the leaves.Yellow fever virus: The type species of the FLAVIVIRUS genus. Principal vector transmission to humans is by AEDES spp. mosquitoes.Defective Viruses: 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.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Infectious bronchitis virus: A species of CORONAVIRUS causing infections in chickens and possibly pheasants. Chicks up to four weeks old are the most severely affected.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Immediate-Early Proteins: Proteins that are coded by immediate-early genes, in the absence of de novo protein synthesis. The term was originally used exclusively for viral regulatory proteins that were synthesized just after viral integration into the host cell. It is also used to describe cellular proteins which are synthesized immediately after the resting cell is stimulated by extracellular signals.Receptors, 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.Mumps virus: The type species of RUBULAVIRUS that causes an acute infectious disease in humans, affecting mainly children. Transmission occurs by droplet infection.Virulence: 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.Neospora: A genus of protozoan parasites of the subclass COCCIDIA. Its species are parasitic in dogs, cattle, goats, and sheep, among others. N. caninum, a species that mainly infects dogs, is intracellular in neural and other cells of the body, multiplies by endodyogeny, has no parasitophorous vacuole, and has numerous rhoptries. It is known to cause lesions in many tissues, especially the brain and spinal cord as well as abortion in the expectant mother.DNA, Viral: Deoxyribonucleic acid that makes up the genetic material of viruses.Viral Interference: A phenomenon in which infection by a first virus results in resistance of cells or tissues to infection by a second, unrelated virus.SARS Virus: A species of CORONAVIRUS causing atypical respiratory disease (SEVERE ACUTE RESPIRATORY SYNDROME) in humans. The organism is believed to have first emerged in Guangdong Province, China, in 2002. The natural host is the Chinese horseshoe bat, RHINOLOPHUS sinicus.Cell Fusion: Fusion of somatic cells in vitro or in vivo, which results in somatic cell hybridization.Encephalitis Virus, Japanese: A species of FLAVIVIRUS, one of the Japanese encephalitis virus group (ENCEPHALITIS VIRUSES, JAPANESE), which is the etiological agent of Japanese encephalitis found in Asia, southeast Asia, and the Indian subcontinent.Brefeldin A: A fungal metabolite which is a macrocyclic lactone exhibiting a wide range of antibiotic activity.Antigens, Viral: Substances elaborated by viruses that have antigenic activity.L Cells (Cell Line): A cultured line of C3H mouse FIBROBLASTS that do not adhere to one another and do not express CADHERINS.Hemagglutinins, Viral: Specific hemagglutinin subtypes encoded by VIRUSES.Viral Nonstructural Proteins: 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.Fluorescent Antibody Technique: Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.Shiga Toxin: A toxin produced by SHIGELLA DYSENTERIAE. It is the prototype of class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; (RNA, RIBOSOMAL) with PEPTIDE ELONGATION FACTORS.Trihexosylceramides: Glycosphingolipids which contain as their polar head group a trisaccharide (galactose-galactose-glucose) moiety bound in glycosidic linkage to the hydroxyl group of ceramide. Their accumulation in tissue, due to a defect in ceramide trihexosidase, is the cause of angiokeratoma corporis diffusum (FABRY DISEASE).Hemadsorption: A phenomenon manifested by an agent or substance adhering to or being adsorbed on the surface of a red blood cell, as tuberculin can be adsorbed on red blood cells under certain conditions. (Stedman, 25th ed)Culicidae: A family of the order DIPTERA that comprises the mosquitoes. The larval stages are aquatic, and the adults can be recognized by the characteristic WINGS, ANIMAL venation, the scales along the wing veins, and the long proboscis. Many species are of particular medical importance.Inclusion Bodies, Viral: An area showing altered staining behavior in the nucleus or cytoplasm of a virus-infected cell. Some inclusion bodies represent "virus factories" in which viral nucleic acid or protein is being synthesized; others are merely artifacts of fixation and staining. One example, Negri bodies, are found in the cytoplasm or processes of nerve cells in animals that have died from rabies.Callitrichinae: A subfamily in the family CEBIDAE that consists of four genera: CALLITHRIX (marmosets), CALLIMICO (Goeldi's monkey), LEONTOPITHECUS (lion tamarins), and SAGUINUS (long-tusked tamarins). The members of this family inhabit the tropical forests of South and Central America.Virion: 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.Melia azedarach: A plant species of the genus MELIA, family MELIACEAE, which is toxic to insects. The name is very similar to Melia azadirachta (AZADIRACHTA).Microscopy, Electron: 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.Gene Expression Regulation, Viral: Any of the processes by which cytoplasmic factors influence the differential control of gene action in viruses.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Respiratory Syncytial Virus, Human: The type species of PNEUMOVIRUS and an important cause of lower respiratory disease in infants and young children. It frequently presents with bronchitis and bronchopneumonia and is further characterized by fever, cough, dyspnea, wheezing, and pallor.Viral Structural Proteins: 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).Viral Vaccines: Suspensions of attenuated or killed viruses administered for the prevention or treatment of infectious viral disease.Giant Cells: Multinucleated masses produced by the fusion of many cells; often associated with viral infections. In AIDS, they are induced when the envelope glycoprotein of the HIV virus binds to the CD4 antigen of uninfected neighboring T4 cells. The resulting syncytium leads to cell death and thus may account for the cytopathic effect of the virus.Mutation: 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.Herpes Simplex: A group of acute infections caused by herpes simplex virus type 1 or type 2 that is characterized by the development of one or more small fluid-filled vesicles with a raised erythematous base on the skin or mucous membrane. It occurs as a primary infection or recurs due to a reactivation of a latent infection. (Dorland, 27th ed.)Coculture Techniques: A technique of culturing mixed cell types in vitro to allow their synergistic or antagonistic interactions, such as on CELL DIFFERENTIATION or APOPTOSIS. Coculture can be of different types of cells, tissues, or organs from normal or disease states.Japanese Encephalitis Vaccines: Vaccines or candidate vaccines used to prevent infection with Japanese B encephalitis virus (ENCEPHALITIS VIRUS, JAPANESE).Escherichia coli: 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.Antigens, CD46: A ubiquitously expressed complement receptor that binds COMPLEMENT C3B and COMPLEMENT C4B and serves as a cofactor for their inactivation. CD46 also interacts with a wide variety of pathogens and mediates immune response.Amino Acid Sequence: 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.Subacute Sclerosing Panencephalitis: A rare, slowly progressive encephalitis caused by chronic infection with the MEASLES VIRUS. The condition occurs primarily in children and young adults, approximately 2-8 years after the initial infection. A gradual decline in intellectual abilities and behavioral alterations are followed by progressive MYOCLONUS; MUSCLE SPASTICITY; SEIZURES; DEMENTIA; autonomic dysfunction; and ATAXIA. DEATH usually occurs 1-3 years after disease onset. Pathologic features include perivascular cuffing, eosinophilic cytoplasmic inclusions, neurophagia, and fibrous gliosis. It is caused by the SSPE virus, which is a defective variant of MEASLES VIRUS. (From Adams et al., Principles of Neurology, 6th ed, pp767-8)HeLa Cells: 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.Idoxuridine: An analog of DEOXYURIDINE that inhibits viral DNA synthesis. The drug is used as an antiviral agent.Viral Fusion Proteins: 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.