- : A microorganism smaller than a bacteria, which cannot grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself. It may reproduce with fidelity or with errors (mutations)—this ability to mutate is responsible for the ability of some viruses to change slightly in each infected person, making treatment more difficult. Viruses cause many common human infections, and are also responsible for a bevy of rare diseases. Examples of viral illnesses range from the common cold, which is usually caused by one of the rhinoviruses, to acquired immunodeficiency syndrome (AIDS), which is caused by the human immunodeficiency virus (HIV). Viruses may contain either DNA or RNA as their genetic material. Herpes simplex virus and the hepatitis- B virus are DNA viruses. RNA viruses have an enzyme called reverse transcriptase that permits the usual sequence of DNA-to-RNA to be reversed so the virus can make a DNA version of itself. RNA viruses include HIV and the hepatitis C virus. Researchers have grouped viruses together into several major families, based on their shape, behavior, and other characteristics. These include the herpesviruses, adenoviruses, papovaviruses (papilloma viruses), hepadnaviruses, poxviruses, and parvoviruses among the DNA viruses. On the RNA virus side, major families include the picornaviruses (including the rhinoviruses), calciviruses, paramyxoviruses, orthomyxoviruses, rhabdoviruses, filoviruses, bornaviruses, and retroviruses. There are dozens of smaller virus families within these major classifications. Many viruses are host-specific, causing disease in humans or specific animals only.
* * *1. Formerly, the specific agent of an infectious disease. 2. Specifically, a term for a group of infectious agents, which with few exceptions are capable of passing through fine filters that retain most bacteria, are usually not visible through the light microscope, lack independent metabolism, and are incapable of growth or reproduction apart from living cells. They have a prokaryotic genetic apparatus but differ sharply from bacteria in other respects. The complete particle usually contains either DNA or RNA, not both, and is usually covered by a protein shell or capsid that protects the nucleic acid. They range in size from 15 nanometers up to several hundred nanometers. Classification of viruses depends upon physiochemical characteristics of virions as well as upon mode of transmission, host range, symptomatology, and other factors. For viruses not listed below, see the specific name. SYN: filtrable v.. 3. Relating to or caused by a v., as a v. disease. 4. (Obsolete usage) Before the era of bacteriology, any agent causing disease, including a chemical substance such as an enzyme (“ferment”) similar to snake venom; synonymous at that time with “poison.” [L. poison]- Abelson murine leukemia v. a retrovirus belonging to the Type C retrovirus group subfamily (family Retroviridae) that is associated with leukemia and induces in vitro transformation of certain mouse cells.- adenosatellite v. SYN: Dependovirus.- Akabane v. a v. of the genus Bunyavirus, family Bunyaviridae, causing abortion in cattle and congenital arthrogryposis and hydranencephaly in bovine fetuses in Israel, Japan, and Australia; it is transmitted by mosquitoes.- amphotropic v. a v. usually associated with retroviruses that may not produce disease in its natural host but does replicate in tissue culture cells of host species as well as in cells from other species.- animal viruses viruses occurring in humans and other animals, either causing inapparent infection or producing disease.- A-P-C v. SYN: adenovirus.- attenuated v. a variant strain of a pathogenic v., so modified as to excite the production of protective antibodies, yet not producing the specific disease.- avian encephalomyelitis v. a v. of the genus Enterovirus (family Picornaviridae) causing avian infectious encephalomyelitis in young chicks.- avian neurolymphomatosis v. the herpesvirus that causes avian lymphomatosis (Marek disease); is distinct from those causing other forms of leukosis. SYN: avian lymphomatosis v., Marek disease v..- avian viral arthritis v. a v. of the genus Reovirus, family Reoviridae, causing tenosynovitis and arthritis in chickens.- B v. SYN: cercopithecrine herpesvirus. SYN: monkey B v..- B19 v. a human parvovirus associated with arthritis and arthralgia and a number of specific clinical entities, including erythema infectiosum and aplastic crisis in the presence of hemolytic anemia.- Barmah Forest v. a species of Alphavirus that has caused outbreaks of polyarthritis in humans in Australia; transmitted by mosquitoes. [the v. was first isolated from mosquitoes collected at the Barmah Forest in southeastern Australia in 1974]- Bayou v. a species of Hantavirus in the U.S. causing hantavirus pulmonary syndrome; transmitted by the rice rat.- BK v. a human polyomavirus, in the family Papovaviridae, of worldwide distribution, that produces kidney infections that are usually subclinical in immunocompetent persons. [initials of patient from whom first isolated]- Black Creek Canal v. a species of Hantavirus in the U.S. causing hantavirus pulmonary syndrome; transmitted by the cotton rat. [Black Creek Canal in Florida where the cotton rats were captured from which the v. was first isolated]- bluetongue v. a v. of the genus Orbivirus, in the family Reoviridae; the agent of bluetongue in sheep.- Bolivian hemorrhagic fever v. a member of the Arenavirus group of single-stranded RNA viruses also known as Machupo v.; primary reservoir in rodents; produces multiple abnormalities in the coagulation system including widespread capillary leak syndrome, which can be fatal.- Borna disease v. an unclassified negative sense single-stranded RNA v. that is the cause of Borna disease, a serious disease of horses that involves infection of the central nervous system. SYN: enzootic encephalomyelitis v..- bovine leukemia v. (BLV) a BLV-HTLV retrovirus in the family Retroviridae, commonly infecting cattle, especially dairy cows; in a small proportion of infected cattle, it will cause enzootic bovine leukosis. SYN: bovine leukosis v..- bovine papular stomatitis v. a poxvirus of the genus Parapoxvirus, reported from North America, Africa and Europe, causing bovine papular stomatitis.- bovine v. diarrhea v. a v. of the genus Pestivirus, in the family Flaviviridae, causing bovine v. diarrhea; New York, Oregon, and Indiana strains of the v. are recognized. SYN: mucosal disease v..- Bunyamwera v. a serologic group of the genus Bunyavirus, composed of over 150 v. types in the family Bunyaviridae. [Bunyamwera, Uganda, where first isolated]- Bwamba v. a species of Bunyavirus in the family Bunyaviridae; associated with cases of Bwamba fever in Uganda. [Bwamba, forest in Uganda where first isolated]- CA v. abbreviation for croup-associated v..- California v. a serologic group of the genus Bunyavirus, comprising about 14 strains including La Crosse and Tahyna v., and the type strain, California v., which causes encephalitis, chiefly in the age group 4–14 years.- canine distemper v. an RNA v. of the genus Morbillivirus, a member of the family Paramyxoviridae, that causes canine distemper. SYN: dog distemper v..- Catu v. an arbovirus of the genus Bunyavirus, of the family Bunyaviridae; an agent of bunyavirus encephalitis.- CELO v. a v. in the Aviadenovirus genus and similar to quail bronchitis v.. SYN: chicken embryo lethal orphan v..- Central European tick-borne encephalitis v. one of the viruses of the tick-borne encephalitis complex of group B arboviruses (genus Flavivirus); the causative agent of tick-borne encephalitis (Central European subtype).- C group viruses a serologic group of the genus Bunyavirus (formerly called group C arboviruses), composed of about 14 species including Caraparu, Murutucu, and Oriboca v..- Chagres v. a v. in the genus Phlebovirus, family Bunyaviridae, an agent of bunyavirus encephalitis.- chikungunya v. a mosquito-transmitted arbovirus of the genus Alphavirus (family Togaviridae) found in parts of Africa and in India, Thailand, and Malaysia; causes a febrile illness with joint pains. [named for the “bent up” position of persons so infected]- Coe v. obsolete name for the A-21 strain of coxsackievirus; the cause of a common-cold-like disease in military recruits.- Colorado tick fever v. a v. of the genus Coltivirus, from the family Reoviridae, found in the Rocky Mountain region of the U.S. and transmitted by the tick, Dermacentor andersoni; it causes Colorado tick fever.- common cold v. any of the numerous strains of v. etiologically associated with the common cold, chiefly the rhinoviruses, but also strains of adenovirus, coxsackievirus, echovirus, and parainfluenza v.. SYN: cold v..- contagious ecthyma (pustular dermatitis) v. of sheep the poxvirus of the genus Parapoxvirus causing contagious ecthyma (pustular dermatitis) of sheep. SYN: soremouth v..- Côte-d'Ivoire v. a variant of Ebola v.. SYN: Ebola v. Côte-d'Ivoire.- coxsackie v. coxsackievirus.- Crimean-Congo hemorrhagic fever v. a v. of the genus Nairovirus (family Bunyaviridae) from Africa and carried by ticks (Hyalomma and Amblyomma) and found in human blood; the cause of Crimean-Congo hemorrhagic fever.- croup-associated v. (CA v.) parainfluenza v. types 1 and 2. See parainfluenza viruses.- cytopathogenic v. a v. whose multiplication leads to degenerative changes in the host cell. SEE ALSO: cytopathic effect.- defective v. a v. particle that contains insufficient nucleic acid to provide for production of all essential viral components; consequently, infectious v. is not produced except under certain conditions ( e.g., when the host cell is infected with a “helper” v. also).- dengue v. a v. of the genus Flavivirus, about 50 nm in diameter; the etiologic agent of dengue in humans and also occurring in monkeys and chimpanzees, usually as inapparent infection; four serotypes are recognized; transmission is effected by mosquitoes of the genus Aedes.- distemper v. canine distemper v..- DNA v. a major group of animal viruses in which the core consists of deoxyribonucleic acid (DNA); it includes parvoviruses, papovaviruses, adenoviruses, herpesviruses, poxviruses, and other unclassified DNA viruses. SYN: deoxyribovirus.- dog distemper v. SYN: canine distemper v..- duck hepatitis v. a DNA v. of the genus Hepadnavirus, in the family Hepadnaviridae, causing v. hepatitis of ducks.- duck influenza v. an influenza A v., a member of the family Orthomyxoviridae, distinct from human influenza A strains on basis of hemagglutination inhibition.- Duvenhage v. a species of Lyssavirus causing a rabieslike disease in humans in Africa; transmitted by the bite of insectivorous bats. [the v. was named after its first victim, a man infected near Pretoria in South Africa]- eastern equine encephalomyelitis v. a v. of the genus Alphavirus (formerly group A arbovirus), in the family Togaviridae, occurring in the eastern U.S.; it is normally present in certain wild birds and small rodents as an inapparent infection, but is capable of causing eastern equine encephalomyelitis in horses and humans following transfer by the bites of culicine mosquitoes. SYN: EEE v..- EB v. SYN: Epstein-Barr v..- Ebola v. a v. of the family Filoviridae, morphologically similar to but antigenically distinct from Marburg v.; the cause of Ebola fever (viral hemorrhagic fever). Transmission is parenteral, not oral, sexual, or by inhalation. After an incubation period of about 1 week, disease comes on acutely with fever, headache, vomiting and diarrhea, weakness, and a maculopapular rash. Gastrointestinal bleeding and other hemorrhagic manifestations, including disseminated intravascular coagulation, appear in a high percentage of cases and often prove fatal. The case fatality rate approximates 80%. Specific prevention and treatment are not available.Ebola v. made the headlines in 1995 when a sudden and devastating outbreak occurred in Kikwit, Zaire. In this cluster, which involved a number of health care workers, 315 persons became infected, of whom 243 (77%) died. Most cases in the Kikwit outbreak were blamed on the re-use, in clinics and hospitals, of unsterile medical and surgical equipment, contaminated with the blood, vomitus, stool, and urine of patients. In the following year, two large outbreaks occurred in Gabon. Serologic studies of patients in Gabon suggest that survival depends on early formation of IgG antibody directed against viral capsular protein. Despite sensational and exaggerated accounts by the news media, epidemics of Ebola v. disease and other viral hemorrhagic fevers do not occur when standard infection control measure are used. Further epidemics will occur in third-world countries as long as poverty and ignorance lead to unsound health care practices, but the disease poses no risk of epidemic spread in developed countries.- Ebola v. Côte-d'Ivoire SYN: Côte-d'Ivoire v..- Ebola v. Reston SYN: Reston v..- Ebola v. Sudan SYN: Sudan v..- Ebola v. Zaire SYN: Zaire v..- ECHO v. an enterovirus from a large group of unrelated viruses belonging to the Picornaviridae, isolated from humans; while there are many inapparent infections, certain of the several serotypes are associated with fever and aseptic meningitis, and some appear to cause mild respiratory disease. SYN: echovirus, enteric cytopathogenic human orphan v..- ECMO v. simian picornavirus recovered from monkey kidney cells and stools. SYN: enteric cytopathogenic monkey orphan v..- ecotropic v. a retrovirus that does not produce disease in its natural host but does replicate in tissue culture cells derived from the host species.- ECSO v. a picornavirus isolated from outbreaks of enteritis in swine, but not known to be a natural pathogen. SYN: enteric cytopathogenic swine orphan v..- EMC v. SYN: encephalomyocarditis v..- emerging viruses in epidemiology, a class of viruses that have long infected humans or animals but now have the opportunity to attain epidemic proportions due to human encroachment on tropical rainforests, increased international travel, burgeoning populations in less developed countries, and, possibly, mutations. A number of viruses have been termed emergent, including hemorrhagic viruses such as Ebola, Marburg, and Hantaan; the rabies-like viruses Mokola and Duvenhage; rodent-borne Junin and Lassa v.; and mosquito-borne dengue. Virologists speculate that the strain of HIV that causes AIDS may also fall into this category, having entered humans through contact with monkeys in central Africa, possibly having existed among monkey populations for some 50,000 years.- encephalomyocarditis v. a Cardiovirus in the family Picornaviridae, usually from rodents, isolated from blood and stools of humans, other primates, pigs, and rabbits; occasionally causes febrile illness with central nervous system involvement in humans, and an often fatal myocarditis in chimpanzees, monkeys and pigs; strains of this v. include Columbia S. K. v. and Mengo v.. SYN: EMC v..- enteric orphan viruses enteroviruses isolated from humans and other animals, “orphan” implying lack of known association with disease when isolated; many viruses of the group are now known to be pathogenic; they include ECBO viruses, ECHO viruses, and ECSO viruses.- epidemic gastroenteritis v. a RNA v., about 27 nm in diameter, which has not been cultured in vitro; it is the cause of epidemic nonbacterial gastroenteritis; at least five antigenically distinct serotypes have been recognized, including the Norwalk agent. These viruses are classified with the Caliciviruses in the family Caliciviridae. SYN: gastroenteritis v. type A.- epidemic keratoconjunctivitis v. an adenovirus (type 8) causing epidemic keratoconjunctivitis, especially among shipyard workers, and also associated with outbreaks of swimming pool conjunctivitis. SYN: shipyard eye.- epidemic pleurodynia v. a v. of Enterovirus coxsackievirus type B, in the family Picornaviridae, that causes epidemic pleurodynia. SYN: Bornholm disease v., epidemic myalgia v..- Epstein-Barr v. (EBV) a herpesvirus in the genus Lymphocryptovirus that causes infectious mononucleosis and is also found in cell cultures of Burkitt lymphoma; associated with nasopharyngeal carcinoma. SYN: EB v., human herpesvirus 4.- filamentous bacterial viruses deoxyribonucleoproteins that “infect” and replicate in Gram-negative bacteria having sex pili and that, unlike bacteriophage, are released from infected bacteria without damage to the cell; they seem to be of two kinds, one of which has a specificity for F pili and the other for I pili. SYN: fibrous bacterial viruses.- filtrable v. SYN: v. (2).- fixed v. rabies v. whose virulence for rabbits has been stabilized by numerous passages through this experimental host. SEE ALSO: street v..- foamy viruses retroviruses of the genus Spumavirus, family Retroviridae, found in primates and other mammals; so named because of lacelike changes produced in monkey kidney cells; syncytia are also produced. SYN: foamy agents.- foot-and-mouth disease v. a picornavirus of the genus Aphthovirus, family Picornaviridae, causing foot-and-mouth disease of cattle, swine, sheep, goats, and wild ruminants; it has wide distribution throughout Africa and Asia, causing serious economic losses; the v. is spread by contamination of the animal environment with infected saliva and excreta. SYN: FMD v..- Four Corners v. SYN: Sin Nombre v.. [from the section of the U.S. where New Mexico, Colorado, Utah, and Arizona meet, site of a major occurrence]- Friend v. a strain of the splenic group of mouse leukemia viruses, related to Moloney and Rauscher viruses. SYN: Friend leukemia v., Swiss mouse leukemia v..- GAL v. a v. with characteristics of adenovirus, not known to be associated with natural disease. SYN: gallus adenolike v..- gallus adenolike v. SYN: GAL v..- GB viruses members of the family Flaviviridae; GBV-A and GBV-B have been isolated from tamarins infected with human viral agents; GBV-C is a human pathogen related to hepatitis G v..- Graffi v. a type C mouse myeloleukemia v. from filtrates of transplantable tumors; possibly related to Gross v..- green monkey v. SYN: Marburg v..- Guama v. a serologic group of the genus Bunyavirus, composed of 6 species including Catu v., and the type strain, Guama v..- Guanarito v. a species of Arenavirus causing Venezuelan hemorrhagic fever. [after municipality in Venezuela where all initial cases of Venezuelan hemorrhagic fever were confirmed]- Guaroa v. a v. of the Bunyamwera group of the genus Bunyavirus, and an agent of bunyavirus encephalitis.- hand-foot-and-mouth disease v. the v. causing hand-foot-and-mouth disease; chiefly type A16 but also types A4, A5, A7, A9, or A10 Entervirus coxsackievirus.- Hantaan v. a Hantavirus of the family Bunyaviridae that causes Korean hemorrhagic fever with renal syndrome.- helper v. a v. whose replication renders it possible for a defective v. or a virusoid (also present in the host cell) to develop into a fully infectious agent.- Hendra v. SYN: equine Morbillivirus. [from Hendra, the suburb of Brisbane, Australia, where it was first isolated]- hepatitis A v. (HAV) an RNA v., genus Hepatovirus, in the family Picornaviridae; the causative agent of viral hepatitis type A. SYN: infectious hepatitis v..- hepatitis B v. (HBV) a DNA v. in the genus Orthohepadnavirus, family Hepadnaviridae; the causative agent of viral hepatitis type B. SYN: serum hepatitis v..- hepatitis C v. (HCV) a non-A, non-B RNA v. causing posttransfusion hepatitis; it a member of the family Flaviviridae. There are now tests to detect hepatitis C infection.- hepatitis D v. a small “defective” RNA v., similar to viroids and virusoids, that requires the presence of hepatitis B v. for replication. The clinical course is variable but is usually more severe than other hepatitides. SYN: delta agent, delta antigen, delta v., hepatitis delta v..- hepatitis E v. (HEV) a RNA v., possibly a Calicivirus, that is the principal cause of enterically transmitted, waterborne, or epidemic non-A, non-B hepatitis occurring primarily in Asia and Africa.- hepatitis G v. (HGV) an RNA v. related to the hepatitis C v., and which may cause co-infection with that agent.- hog cholera v. an RNA v. of the genus Pestivirus, in the family Flaviviridae, that causes hog cholera. SYN: swine fever v..- human immunodeficiency v. (HIV) human T-cell lymphotropic v. type III; a cytopathic retrovirus (genus Lentvirus, family Retroviridae) that is 100–120 nm in diameter, has a lipid envelope, and has a characteristic dense cylindrical nucleoid containing core proteins and genomic RNA. There are currently two types: HIV-1 infects only human and chimpanzees and is more virulent than HIV-2, which is more closely related to Simian or monkey viruses. HIV-2 is found primarily in West Africa and is not as widespread as HIV-1. In addition to the usual gene associated with retroviruses, this v. has at least 6 genes that regulate its replication. It is the etiologic agent of acquired immunodeficiency syndrome (AIDS). Formerly or also known as the lymphadenopathy v. (LAV) or the human T-cell lymphotropic v. type III (HTLV-III). Identified in 1984 by Luc Montagnier and colleagues. SYN: lymphadenopathy-associated v..- human immunodeficiency v.-2 a v., found primarily in West Africa, which causes a less virulent form of AIDS and is more closely related to Simian v. strains.- human T-cell lymphoma/leukemia v. (HTLV) a group of viruses (genus BLTV-HTLV retroviruses, family Retroviridae) that are lymphotropic with a selective affinity for the helper/inducer cell subset of T lymphocytes and that are associated with adult T-cell leukemia and tropical spastic paraparesis. SYN: human T-cell lymphotropic v..- human T lymphotrophic v. a v. that has a predilection for human lymphoid cells.- v. III of rabbits obsolete name for a latent herpesvirus infection of rabbits. [the third strain isolated, used for study]- Ilhéus v. a v. of the genus Flavivirus (group B arbovirus) first isolated in Brazil, later found in Colombia, Central America, and the Caribbean; the cause of Ilhéus encephalitis and Ilhéus fever.- infectious ectromelia v. a v. belonging to the family Poxviridae morphologically similar to vaccinia v., which occurs as a latent infection in laboratory mice, but which may be activated by stresses such as irradiation and transport to cause disease; inoculation into the footpad results in edema and necrosis. SYN: ectromelia v., mousepox v., pseudolymphocytic choriomeningitis v..- influenza viruses viruses of the family Orthomyxoviridae that cause influenza and influenzalike infections of humans and other animals. These viruses contain single-stranded RNA that is segmented, accounting in part, for their epidemic spread. Viruses included are influenza v. types A and B of the genus Influenzavirus, causing, respectively, influenza A and B, and Influenzavirus C, which belongs to a separate genus and causes influenza C.- insect viruses viruses pathogenic for insects.- Jamestown Canyon v. a member of the California group of arboviruses (family Bunyaviridae), which has been associated with a mild febrile illness in humans in North America.- Japanese B encephalitis v. a v. of the genus Flavivirus (group B arbovirus) occurring particularly in Japan but probably widespread throughout Southeast Asia; the v. is normally present in humans, especially in children, as an inapparent infection, but may cause febrile response and sometimes encephalitis; it may cause encephalitis in horses and abortion in pigs; wild birds are probably the natural hosts and culicine mosquitoes the vectors. SYN: Russian autumn encephalitis v..- JC v. a human polyomavirus, family Papovaviridae, of worldwide distribution which produces infections that are usually subclinical in immunocompetent individuals, but is associated with progressive multifocal leukoencephalopathy in immunosuppressed individuals. [initials of patient from whom first isolated]- Junin v. a v. of the Tacaribe complex of arboviruses, genus Arenavirus, and the cause of Argentinian hemorrhagic fever; also isolated from mites and rodents.- K v. a polyomavirus, family Papovaviridae, that causes pneumonia in young mice by various routes of inoculation.- Kasokero v. a v. of the family Bunyaviridae causing a febrile disease in humans characterized by headache, abdominal pain, diarrhea, severe myalgia, and arthralgia. [after the Kasokero Cave in Uganda where the v. was first isolated from bats]- Kilham rat v. a v. of the genus Parvovirus causing inapparent infection in rats; also recoverable from rat tumors. SYN: latent rat v..- Koongol viruses a serologic group of the genus Bunyavirus, comprising two species, Koongol (type species) and Wongal v..- Kyasanur Forest disease v. a group B arbovirus, in the family Flaviviridae, isolated from monkeys in India and capable of causing Kyasanur Forest disease in humans; the v. is spread by monkeys and birds having mild infections; the vectors are probably species of the tick Haemaphysalis.- La Crosse v. a bunyavirus of the California group, family Bunyaviridae, and an agent of bunyavirus encephalitis.- lactate dehydrogenase v. an arterivirus present perhaps as a “passenger” in various transplantable mouse tumors; the v. may cause a life-long infection and be recognized by elevated plasma lactate dehydrogenose. SYN: LDH agent.- Lassa v. an arenavirus, family Arenaviridae, that causes Lassa fever, an acute febrile disease with a high mortality.- latent rat v. SYN: Kilham rat v..- louping-ill v. a v. of the genus Flavivirus that causes louping ill and is transmitted by the hard tick Ixodes ricinus.- lymphocytic choriomeningitis v. an RNA v. of the family Arenaviridae that infects mice, man, monkeys, dogs, and guinea pig s, and causes lymphocytic choriomeningitis; in man, infection may be inapparent, but sometimes the v. causes influenza-like disease, meningitis, or rarely meningoencephalomyelitis; in utero infections of mice establish a type of immunologic tolerance. SYN: LCM v..- lymphogranuloma venereum v. former name for Chlamydia trachomatis.- Machupo v. a v. of the Tacaribe complex (genus Arenavirus, family Arenaviridae); the cause of Bolivian hemorrhagic fever.- malignant catarrhal fever v. a herpesvirus of wide distribution causing malignant catarrhal fever of cattle; sheep and wildebeests harbor inapparent infections and may transmit the v. to cattle.- mammary tumor v. of mice one of the mammalian Type B retroviruses, antigenically distinct from the murine leukemia-sarcoma complex, that is associated with adenocarcinomatous tumors of the mammary gland, commonly latent in wild and laboratory mice and causing cancer only in genetically susceptible strains under certain hormonal influences. SYN: Bittner agent, Bittner milk factor, Bittner v., mammary cancer v. of mice, milk factor, mouse mammary tumor v..- Marburg v. an RNA-containing v., genus Filovirus in the family Filoviridae, first recognized at Marburg University (Germany), where it was the cause of a highly fatal hemorrhagic fever among laboratory workers and handlers of green monkeys. SYN: green monkey v..- masked v. a v. ordinarily occurring in the host in a noninfective state, but which may be activated and demonstrated by special procedures such as blind passage in experimental animals.- Mason-Pfizer v. a member of the genus D-type retroviruses in the family Retroviridae that was isolated from a mammary carcinoma of a rhesus monkey.- Mayaro v. a v. of the genus Alphavirus, family Togaviridae, causing epidemics of undifferentiated type fever in South America.- measles v. an RNA v. of the genus Morbillivirus, family Paramyxoviridae, that causes measles in humans and is transmitted via the respiratory tract; possesses hemagglutinating, hemadsorbing, and hemolyzing properties. SYN: rubeola v..- Menangle v. a v. of the family Paramyxoviridae causing infection in pigs, humans, and fruit bats in Australia; human infection has resulted in an influenzalike illness with rash. [named after the location in Australia of the laboratory where it was first isolated]- Mokola v. a rabies related v. of the genus Lyssavirus, family Rhabdoviridae, first isolated from shrews (Crocidura spp.) in Nigeria, which has caused fatal neurologic disease in humans and cats in Africa.- Moloney v. a lymphoid leukemia retrovirus of mice, in the family Retroviridae, isolated originally during propagation of S 37 mouse sarcoma.- monkey B v. SYN: B v..- mouse encephalomyelitis v. a v. of the genus Enterovirus, family Picornaviridae, normally associated with inapparent infections and found in the intestinal tracts of infected mice, occasionally causing mouse encephalomyelitis in experimentally inoculated susceptible mice. SYN: mouse poliomyelitis v., Theiler v..- mouse hepatitis v. a coronavirus, in the family Coronaviridae, that in the presence of Eperythrozoon coccoides causes fatal hepatitis in newly weaned mice; otherwise causes inapparent infection.- mouse leukemia viruses retroviruses of the murine leukemia-sarcoma complex that produce leukemia and sometimes lymphosarcomas in mice, including the Abelson, Gross, Moloney, Friend, and Rauscher strains of v.; they have been isolated from inbred mice having a high incidence of spontaneous lymphoid leukemia.- mouse thymic v. an ether-sensitive member of the herpesviridae family that causes necrosis of the thymus in young mice.- mumps v. a v. of the genus Rubulavirus, family Paramyxoviridae, causing parotitis in man, sometimes with complications of orchitis, oophoritis, pancreatitis, meningoencephalitis, and others, and transmitted by infectious salivary secretions. SYN: epidemic parotitis v..- murine sarcoma v. a seemingly defective retrovirus that produces sarcomas in mice when growing in the presence of a “helper” v.; e.g., mouse leukemia v..- Murray Valley encephalitis v. a group B arbovirus of the genus Flavivirus that causes Murray Valley encephalitis; it is transmitted by Culex mosquitoes, and also infects birds and horses. SYN: Australian X disease v., MVE v..- Murutucu v. a C group mosquito-borne v. of the genus Bunyavirus, which has caused undifferentiated type fever in Brazil and French Guiana.- naked v. a v. consisting only of a nucleocapsid; i.e., one that does not possess an enclosing envelope.- ND v. SYN: Newcastle disease v..- negative strand v. a v. the genome of which is a strand of RNA that is complementary to messenger RNA; negative strand viruses also carry RNA polymerases necessary for the synthesis of messenger RNA.- Negishi v. one of the group B arboviruses (genus Flavivirus) of the tick-borne encephalitis complex, isolated from fatal infections in Japan.- neonatal calf diarrhea v. one of two viruses causing neonatal calf diarrhea; a rotovirus-like v. is associated with disease in newborn calves, and a coronavirus is associated with disease in calves over 5 days of age.- neurotropic v. a v. that has an affinity for nervous tissue, e.g., poliomyelitis v., neurotropic v. variant of yellow fever, and the “fixed” v. of rabies.- Newcastle disease v. a v. of the genus Rubulavirus, family Paranexoviridae, causing Newcastle disease in chickens and, to a lesser extent, in turkeys and other birds; it may occasionally infect laboratory and poultry workers, causing conjunctivitis and lymphadenitis. SYN: avian pneumoencephalitis v., ND v..- Nipah v. a paramyxovirus that can cause fatal disease in humans, with features of encephalitis and meningitis; the v. spreads from swine to humans. [Nipah, Malaysia, where first human case detected, 2000]- non-A, non-B hepatitis v. term used to group any of a number of viruses, other than A or B, that cause hepatitis in humans.- Norwalk v. a v. associated with acute viral gastroenteritis and belonging to the calicivirus group.- oncogenic v. any v. capable of inducing tumors. The RNA tumor viruses (family Retroviridae), which are well-defined and rather homogeneous, or the DNA viruses, which contain a number of viruses capable of inducing tumors, including poxviruses, herpesviruses, papillomaviruses, and polyomavirus. SYN: tumor v..- o'nyong-nyong v. a v. of the genus Alphavirus, in the family Togaviridae, found in Uganda, Kenya, and Congo, which causes o'nyong-nyong fever.- orf v. a parapoxvirus causing orf in sheep and goats and sometimes humans. SYN: contagious pustular dermatitis, contagious pustular stomatitis v. (2).- ornithosis v. former name for Chlamydia psittaci.- orphan viruses viruses, such as the enteric orphan viruses, that when originally found were not specifically associated with disease; a number of these have since been shown to be pathogenic and subsequently reclassified.- Pacheco parrot disease v. a v. of the family Herpesviridae, possibly related to the v. of infectious laryngotracheitis. SYN: parrot v. (2).- pantropic v. the ordinary strain of yellow fever v., as distinguished from the neurotropic strain; has an affinity for different tissues.- parainfluenza viruses viruses of the genus Paramyxovirus, of four types: type 1 (hemadsorption v. type 2), which includes sendai v., causes acute laryngotracheitis in children and occasionally adults; type 2 (croup-associated v.) is associated especially with acute laryngotracheitis or croup in young children and minor upper respiratory infections in adults; type 3 (hemadsorption v. type 1; shipping fever v.) has been isolated from small children with pharyngitis, bronchiolitis, and pneumonia, and causes occasional respiratory infection in adults; bovine strains have been isolated from cattle with shipping fever, and the v. has also been isolated from sheep; type 4 has been isolated from a very few children with minor respiratory illness.- pharyngoconjunctival fever v. one of several types of adenoviruses associated with outbreaks of fever and pharyngitis, sometimes with conjunctivitis, especially in military recruits and people in boarding schools.- phlebotomus fever viruses a group of at least 5 viruses in the family Bunyavirida but antigenically unrelated, transmitted by Phlebotomus papatasi (sandfly) and causing phlebotomus fever. SYN: pappataci fever viruses, sandfly fever viruses.- plant viruses viruses pathogenic to higher plants.- pneumonia v. of mice an RNA v. of the genus Pneumovirus, a member of the family Paramyxoviridae, occurring normally as latent infection in laboratory mice, but capable of activation by serial intranasal passage and causing pneumonia. SYN: PVM v..- poliomyelitis v. a small single-stranded RNA v. of the genus Enterovirus, family Picornaviridae, causing poliomyelitis in humans; the route of infection is the alimentary tract, but the v. may enter the bloodstream and nervous system, sometimes causing paralysis of the limbs and, rarely, encephalitis; many infections are inapparent; serologic types 1, 2, and 3 are recognized, type 1 being responsible for most paralytic poliomyelitis and most epidemics. SYN: poliovirus hominis.- polyoma v. a small naked v. with double-stranded circular DNA (genus Polyomavirus, family Papovaviridae) that normally occurs in inapparent infections in laboratory and wild mice, but after growth on tissue culture is capable of producing parotid tumors in mice and sarcomas in hamsters as well as tumors in other laboratory animals. SYN: mouse parotid tumor v..- porcine hemagglutinating encephalomyelitis v. a Coronavirus causing vomiting, wasting, and encephalomyelitis in young pigs.- Powassan v. a v. of the genus Flavivirus (family Flaviviridae), transmitted by ixodid ticks and causing Powassan encephalitis in children; also capable of producing meningoencephalomyelitis in rabbits and children. [Powassan, Canada, where first isolated]- pseudocowpox v. a v. of the genus Parapoxvirus that causes pseudocowpox in humans and cattle; it is closely related to orf v. and papular stomatitis v.. SYN: paravaccinia v..- pseudorabies v. a herpesvirus, family Herpesviridae, causing pseudorabies in swine. SYN: Aujeszky disease v..- psittacosis v. former name for Chlamydia psittaci.- PVM v. SYN: pneumonia v. of mice.- rabbit fibroma v. a poxvirus of the genus Leporipoxvirus, family Poxviridae, closely related to vaccinia and myxoma viruses, that causes Shope fibroma. SYN: Shope fibroma v..- rabbit myxoma v. the poxvirus of the genus Leporipoxvirus causing myxomatosis of rabbits. SYN: myxomatosis v..- rabbitpox v. an Orthopoxvirus that causes epidemics of pox in laboratory rabbits; immunologically, it is closely related to vaccinia v. but is more virulent in rabbits.- rabies v. a large bullet-shaped single-stranded RNA v. of the genus Lyssavirus, in the family Rhabdoviridae, that is the causative agent of rabies.- rabies v., Flury strain a v. isolated from human brain, attenuated (fixed) by serial propagation in nonmammalian hosts, and subsequently established in chick embryo culture.- Rauscher leukemia v. an RNA retrovirus associated with leukemia in rodents; similar to Friend v.. SYN: Rauscher v..- respiratory enteric orphan v. a nonenveloped icosahedral v. with a two-layered capsid whose genome consists of multiple segments of double-stranded RNA, belonging to the family Reoviridae, frequently found in both the respiratory and enteric tract. SYN: REO v..- respiratory syncytial v. (RSV) an RNA v. of the genus Pneumovirus, in the family Paramyxoviridae, with a tendency to form syncytia in tissue culture, that causes minor respiratory infection with rhinitis and cough in adults, but is capable of causing severe bronchitis and bronchopneumonia in young children; first isolated from chimpanzees with respiratory disease. SYN: chimpanzee coryza agent, Rs v..- Reston v. a variant of Ebola v.. SYN: Ebola v. Reston.- Rift Valley fever v. a v. of the genus Phlebovirus (family Bunyaviridae) that occurs in central and southern Africa in sheep, goats, and cattle, causing abortions and severe febrile disease, especially in young lambs; humans, especially herdsmen and veterinarians, may become infected through close contact with infected animals, developing a dengue-like disease; the v. also infects buffaloes, camels, and antelopes; it is mosquito-borne, but also probably infects by contact and respiratory tract.- RNA v. a group of viruses in which the core consists of RNA; a major group of animal viruses that includes the families Picornaviridae, Reoviridae, Togaviridae, Flaviviridae, Bunyaviridae, Arenaviridae, Paramyxoviridae, Retroviridae, Coronaviridae, Orthomyxoviridae, and Rhabdoviridae. SYN: ribovirus.- Ross River v. a mosquito-borne alphavirus, family Togaviridae, that causes epidemic polyarthritis.- Rous-associated v. (RAV) a leukemia v. of the Avian type C retroviruses (leukosis-sarcoma complex), family Retroviridae, that by phenotypic mixing with a defective (noninfectious) strain of Rous sarcoma v. effects production of infectious sarcoma v. with envelope antigenicity of the RAV.- Rous sarcoma v. (RSV) a sarcoma-producing v. of the Avian type C retroviruses (leukosis-sarcoma complex), family Retroviridae identified by Rous in 1911.- rubella v. an RNA v. of the genus Rubivirus in the family Togaviridae; the agent causing rubella (German measles) in humans. SYN: German measles v..- Salisbury common cold viruses strains of rhinovirus of historical interest because of early studies that established the viral etiology of common colds.- salivary v. SYN: human herpesvirus 5.- San Miguel sea lion v. a calicivirus, family Caliciviridae, first isolated from sea lions on San Miguel island off the California coast, which is indistinguishable from the vesicular exanthema of swine v. both biophysically and clinically in terms of the vesicular disease syndrome that it produces in swine.- Sendai v. a parainfluenza v. type 1 reported to cause inapparent infection in many animals; also used extensively to effect fusion of tissue culture cells.- Seoul v. a species of Hantavirus in the Far East causing hemorrhagic fever with renal syndrome. [the v. was named after Seoul in South Korea, the city where it was first isolated.]- Simbu v. a serologic group of the genus Bunyavirus, comprising a number of species including the type strain, Simbu v..- simian v. (SV) any of a number of viruses, belonging to various families, isolated from monkeys or from cultures of monkey cells. SYN: vacuolating v..- simian v. 40 SYN: simian vacuolating v. No. 40.- simian vacuolating v. No. 40 (SV40) a small (40–45 nm) DNA v. of the genus Polyomavirus, family Papovaviridae; the cause of seemingly inapparent infections in monkeys, especially rhesus, and a common contaminant of monkey cell cultures; the v. may cause inapparent infection in humans and may be excreted in stools of children for several weeks; it can produce fibrosarcoma in suckling hamsters, and transformation may occur in human diploid cells; it may also form “hybrid” v. in cells also infected with certain adenoviruses. SYN: simian v. 40.- Sindbis v. the type species of the genus Alphavirus, in the family Togaviridae, usually transmitted by mosquitoes of the genus Culex; and causative agent of Sindbis fever. [village in Egypt where first isolated]- Sin Nombre v. a species of Hantavirus in North America causing hantavirus pulmonary syndrome. SYN: Four Corners v.. [Spanish, without a name]- slow v. a v., or a viruslike agent, etiologically associated with a disease having a long incubation period of months to years with a gradual onset frequently terminating in severe illness and/or death.- snowshoe hare v. a member of the California group of arboviruses, genus Bunyavirus, family Bunyaviridae, causing fever, severe headache, and nausea in humans in North America.- Spondweni v. an arbovirus of the genus Flavivirus isolated from mosquitoes in Africa; may cause disease in humans.- St. Louis encephalitis v. a group B arbovirus, genus Flavivirus in the family Flaviviridae, occurring in the U.S., Trinidad, and Panama; normally present as inapparent infection in humans, but sometimes a cause of encephalitis; the v. has been isolated from birds in Panama and from several mosquito species, especially Psorophora.- Sudan v. a variant of Ebola v.. SYN: Ebola v. Sudan.- swine influenza viruses strains of influenza v. type A which cause influenza of swine and can infect humans.- swinepox v. a poxvirus genus Suipoxvirus distinct from vaccinia v. and the cause of swinepox; the pig louse plays an important role in transmission.- Tacaribe v. the type v. of the Tacaribe complex of viruses of genus Arenaviruses isolated from bats and mosquitoes in Trinidad.- Tahyna v. a California group arbovirus genus Bunyavirus, in the family Bunyaviridae, from central Europe, known to infect humans.- Taiwan Dobrava-Belgrade v. a species of Hantavirus in the Balkans causing hemorrhagic fever with renal syndrome. [after Dobrava, Slovenia (where first isolated from field mice) and Belgrade, Yugoslavia (where first isolated from humans)]- temperate v. referring to a phage that does not lyse its host immediately but may persist in latent form and eventually lyse its host. See lysogeny.- Teschen disease v. a picornavirus causing Teschen disease of pigs; the v. is normally a harmless inhabitant of the intestinal tract, but virulent strains cause epizootics of the disease. SYN: infectious porcine encephalomyelitis v..- Theiler mouse encephalomyelitis v. a v. genus Cardiovirus in the family Picornaviridae. SYN: Theiler original v..- tick-borne v. SYN: tick-borne encephalitis v..- tick-borne encephalitis v. arboviruses of the genus Flavivirus that occur in Central Europe and Russia in multiple subtypes, causing two forms of encephalitis in humans: tick-borne encephalitis (Central European subtype) and tick-borne encephalitis (Eastern subtype); the vectors are ticks of the genus Ixodes. SYN: Russian spring-summer encephalitis v., tick-borne v..- trachoma v. former name for Chlamydia trachomatis.- transmissible gastroenteritis v. of swine a genus Coronavirus that causes transmissible gastroenteritis of swine. SYN: TGE v..- Turlock v. an unclassified serologic group of arboviruses in the genus Bunyavirus but antigenically unrelated to it.- Umbre v. a Bunyavirus related serologically to the Turlock v..- vaccinia v. the poxvirus (genus Orthopoxvirus) used in the immunization of people against variola (smallpox), usually causing a local reaction but sometimes generalized vaccinia, especially in children; the v. is closely related serologically to the viruses of variola and cowpox, but certain differences have been demonstrated which indicate that they are perhaps distinct but closely related strains of a variola-vaccinia-cowpox complex; the lineage of vaccinia v. is uncertain, and it is very unlikely that it descended from Jenner original v.. SYN: poxvirus officinalis.- vacuolating v. SYN: simian v..- varicella-zoster v. a herpesvirus, morphologically identical to herpes simplex v., that causes varicella (chickenpox) and herpes zoster in man; varicella results from a primary infection with the v.; herpes zoster results from secondary invasion by the same v. or by reactivation of infection which in many instances has been latent for many years. SYN: chickenpox v., herpes zoster v., human herpesvirus 3, Varicellovirus.- variola v. a poxvirus of the genus Orthopoxvirus, the pathogen of smallpox in humans. SYN: smallpox v..- Venezuelan equine encephalomyelitis v. a group A arbovirus of the genus Alphavirus, family Togaviridae, occurring in Venezuela and several other South American countries, in Panama and Trinidad, and occasionally the U.S. causing Venezuelan equine encephalomyelitis in horses and humans; it seems to be more viscerotropic than neurotropic; the v. is transmitted by Culex mosquitoes. SYN: VEE v..- vesicular exanthema of swine v. a Calicivirus causing vesicular exanthema of swine. SEE ALSO: San Miguel sea lion v..- vesicular stomatitis v. an RNA v. of the genus Vesiculovirus, in the family Rhabdoviridae, causing vesicular stomatitis in horses, cattle, sheep, and pigs. SYN: VS v..- viral hemorrhagic fever v. any one of more than 15 different viruses that cause hemorrhagic fever.- visna v. an RNA v. a Lentivirus (family Retroviridae) that causes visna; it is closely related antigenically to the similar maedi v..- Wesselsbron disease v. a mosquito-borne group B arbovirus of the genus Flavivirus causing Wesselsbron fever.- western equine encephalomyelitis v. a group A arbovirus of the genus Alphavirus, family Togaviridae, occurring in the western U.S. and parts of South America; it occurs naturally, usually as a symptomless infection in birds, but causes western equine encephalomyelitis in horses and humans following transfer by the bites of mosquitoes, chiefly Culex tarsalis. SYN: WEE v..- xenotropic v. a retrovirus that does not produce disease in its natural host and replicates only in tissue culture cells derived from a different species.- Yaba v. a poxvirus from the Yatapoxvirus, family Poxviridae, distinct from monkeypox v., that causes Yaba tumors in monkeys. SYN: Yaba monkey v..- Yaba monkey v. SYN: Yaba v..- yellow fever v. an arbovirus, the type species of the genus Flavivirus, in the family Flaviviridae, endemic in tropical Africa south of the Sahara and in tropical South America, occasionally spreading to countries outside these areas; it is the cause of yellow fever of humans and other primates; the v. exists in wild primates, and probably also in edentates, marsupials, and rodents, and is transmitted to humans by Aedes aegypti and the Haemagogus complex of tree-top mosquitoes that feed on arboreal mammals.- Zaire v. a variant of Ebola v.. SYN: Ebola v. Zaire.- Zika v. a mosquito-borne v. of the genus Flavivirus (family Flaviviridae), found in parts of Africa and in Malaysia, that causes Zika fever. [Zika, forest in Uganda, where first isolated]
* * *vi·rus 'vī-rəs n1 a) the causative agent of an infectious diseaseb) any of a large group of submicroscopic infective agents that are regarded either as extremely simple microorganisms or as extremely complex molecules, that typically contain a protein coat surrounding an RNA or DNA core of genetic material but no semipermeable membrane, that are capable of growth and multiplication only in living cells, and that cause various important diseases in humans, animals, or plants also FILTERABLE VIRUSc) a disease caused by a virus2) an antigenic but not infective material (as vaccine lymph) obtainable from a case of an infectious disease
* * *n.a minute particle that is capable of replication but only within living cells. Viruses are too small to be visible with a light microscope and too small to be trapped by filters. They infect animals, plants, and microorganisms (see bacteriophage). Each consists of a core of nucleic acid (DNA or RNA) surrounded by a protein shell. Some bear an outer lipid capsule. Viruses cause many diseases, including the common cold, influenza, measles, mumps, chickenpox, herpes, AIDS, polio, and rabies. antiviral drug are effective against some of them, and many viral diseases are controlled by means of vaccines.• viral adj.
* * *vi·rus (viґrəs) [L.] one of a group of minute infectious agents, usually not resolvable under a light microscope, although there are certain exceptions such as poxviruses. Viruses are characterized by lack of independent metabolism and by the ability to replicate only within living host cells. Like living organisms, they can reproduce with genetic continuity and the possibility of mutation. They range from 200â€“300 nm to 15 nm in size and are morphologically heterogeneous, occurring as rod-shaped, spherical, or polyhedral, and tadpole-shaped forms; masses of the spherical or polyhedral forms may be made up of orderly arrays to give a crystalline structure. The individual particle, or virion, consists of nucleic acid (the nucleoid), DNA or RNA (but not both) and a protein shell, or capsid, which contains and protects the nucleic acid and may be multilayered. Viruses are customarily separated into three subgroups on the basis of host specificity, namely bacterial viruses, animal viruses, and plant viruses. They are also classified as to their origin (e.g., reoviruses), mode of transmission (arboviruses, tick-borne viruses), or the manifestations they produce (polioviruses, polyomaviruses, poxviruses). They are sometimes named for the geographical location in which they were first isolated (e.g., coxsackievirus).
PLATE 49 STRUCTURE OF VARIOUS VIRUSES AND LIFE CYCLE OF HUMAN IMMUNODEFICIENCY VIRUS
Many of the names listed below are names of virus species; species names in viral taxonomy do not use Latin binomial nomenclature and are neither capitalized (unless the species name includes a proper name) nor italicized.
Medical dictionary. 2011.