Epidermodysplasia verruciformis EV

Widespread and persistent dissemination of flat warts (verruca plana), sometimes for decades, which can progress to malignancy. Often associated with HPV types 5 and 8. Found particularly in immuno-suppressed persons, e.g. AIDS patients. Synonym: Lewandowsky-Lutz disease.

episomes Plasmids which can be integrated into the cell genome, where they behave as part of a chromosome. Phage lambda is an example. May behave as an episome in one cell and a plasmid (replicating independently of the chromosome) in another.

epithelial cells Epithelial cells in culture form tight junctions and become polarized into apical and basolateral regions. Enveloped viruses bud from one or other of these surfaces, and usually not from both.

Tucker SP and Compans RW (1993) Adv Virus Res 42, 187

epithelioma contagiosum virus Synonym for Fowlpox virus.

epithelioma of carp virus Synonym for cyprinid herpesvirus 1.

epithelioma papillosum of carp virus

Synonym for cyprinid herpesvirus 1.

epitope The structure of an antigen which elicits the formation of specific antibodies, e.g. a grouping of amino acid sequences on a protein, or between adjacent protein subunits; also termed 'antigenic site'. The term was coined in 1960 by Jerne, who proposed that 'an antigen particle carries several epitopes'. Various types of epitope have been distinguished: cryptotope, which is buried inside the antigen and becomes reactive only after denaturation or dissociation of the antigen; neotope, which arises from changes in folding of the polypep-tide chain; metatope, which is formed from adjacent protein molecules during assembly of structures from subunits; and mimotope, which is a peptide structure that mimics the shape of an epitope. The structure on the antibody which is complementary to the epitope is termed the paratope. In the cell-mediated immune response, T-cells recognize epitopes of processed proteins in a complex with HLA (MHC) molecules.

Laver WG et al (1980) Cell 61, 553

van Regenmortel MHV (1966) Adv Virus Res

12, 207

epitope analysis Analysis of the primary structures of proteins may not reveal the antigenic determinants that are important epitopes for the immune system. The complete structure of an epitope can be determined by X-ray diffraction of crystals of a complex of a monoclonal antibody Fab fragment with its antigen.

Yewdell JW et al (1999) In Encyclopedia of Virology, Second edition, edited by A Granoff and RG Webster. London: Academic Press, p. 836

Epivir-HBV Approved to fight HIV infections in 1995 this drug works as a reverse transcriptase inhibitor by blocking an enzyme the AIDS virus uses to reproduce. It is now also approved to treat chronic hepatitis B. Synonyms: Lamivudine, 3TC.

epizootic A disease temporarily present in an animal community, attacking many animals at the same time, spreading rapidly and becoming widely diffused. Analogous to an epidemic in human populations.

epizootic cellulitis virus Synonym for

Equine arteritis virus.

Epizootic hemorrhagic disease virus 1-8 (EHDV 1-8) A species in the genus Orbivirus belonging to the epizootic hem-orrhagic disease serogroup. Has caused fatal epizootics in Virginian white-tailed deer, Odocoileus virginianus. Mule deer and other species are not susceptible. After an incubation period of 6-8 days there are signs of shock, multiple hemorrhages, coma and death. Virus can be passed i.c. in suckling mice and loses virulence for deer. There are eight serotypes of EHDV; Ibaraki virus which affects cattle in Japan is an antigenically related member of the EHDV group. EHDV is found in USA, Canada and Australia, where cattle, buffalo and deer are infected by at least five serotypes without clinical disease. Infection does not pass by direct contact and the principal arthropod vectors are Culicoides sp. Injection into European deer, sheep, goats and cattle leads to a silent infection. Not reported to cause disease in humans.

Hourrigan JL and Klingsporn AL (1975) Austr Vet J 51, 203

epizootic hematopoietic necrosis virus (EHNV) A tentative species in the genus Ranavirus, affecting at least 13 genera of fish including rainbow trout and redfin perch.

epizootiology The study of factors involved in the spread of diseases in animal populations.

Dohoo IR et al (1994) Nature 368, 284 Mims CA (1991) Epidemiol Infect 106, 423

epornotic An epidemic of disease amongst birds.

Epsilonretrovirus A genus of exogenous retroviruses that infect reptiles and fish. They are complex, with genomes ranging from 11.7 to 12.8 kb. Walleye dermal sarcoma virus uses a tRNAHis primer, but snake-head retrovirus uses tRNAArg.

Epstein-Barr virus Synonym for Human herpesvirus 4.

equestron Name given to a postulated regulatory protein produced during human poliovirus replication. It would regulate the suppression of host protein synthesis and control the production of viral RNA and protein. No satisfactory evidence in favor of the existence of this regulator has been forthcoming.

Cooper PD et al (1973) Intervirology 1, 1

Equid herpesvirus 1 (EHV-1) A species in the genus Varicellovirus, closely related to EHV-4. A natural infection confined to equines. A common cause of acute respiratory disease in horses during their first 2 years of life. Natural transmission probably by respiratory route. Usually silent in mares but abortion may occur, especially in months 8-10 of pregnancy. Should not be confused with equine infectious arteritis virus which can also cause abortion in mares. Experimental infection during the months 3-9 of gestation may result in encephalitis due to vasculitis. Genital vesicular exanthema or pustular vulvovaginitis may be produced. Experimentally, causes abortion in guinea pigs; suckling hamsters infected i.p. develop hepatitis. Has been adapted to growth on the CAM, in the yolk sac and amnion. Replicates with CPE in fetal horse cell cultures, also in HeLa, human amnion, sheep, pig, cattle, cat and chick cell cultures. Live virus given to non-pregnant mares is safe and gives protection.

Synonyms: Equid herpesvirus 1; equine abortion virus; equine influenza virus; equine rhinopneumonitis virus; mare abortion virus; equine abortion her-pesvirus.

Crabb BS and Studdert MJ (1995) Adv Virus Res 45, 159

Equid herpesvirus 2 (EHV-2) A species in the genus Rhadinovirus. Originally isolated from a horse with catarrh, but usually causes only mild disease or silent infection. Is widespread and can be isolated from infected horses over a prolonged period. A slowly replicating cytomegalo-type virus that is not host-cell specific. There are several serotypes, and the viruses numbered by Plummer as types 2, 3 and 4 are probably best regarded as serotypes of Equid herpesvirus 2. Serologically distinct from equid her-pesviruses 1 and 3. Synonym: equine cytomegalovirus.

Agius CT and Studdert MJ (1994) Adv Virus Res 44, 357

Browning GF and Studdert MJ (1989) Arch Virol 104, 77

Telford EA et al (1995) J Mol Biol 249, 520

equid herpesvirus 3 (EHV-3) A tentative species in the genus Varicellovirus. Isolated from horses during an outbreak of coital exanthema, an acute, relatively mild disease in which there are pustular lesions on the external genitalia and vagina. Cross-neutralization tests showed it to be distinct from equid herpesviruses 1 and 2. Transmission experiments with this virus produced typical equine coital exanthema, except in one animal which had recently recovered from the disease. Synonyms: coital exanthema virus; equine herpesvirus 3.

Studdert MJ (1974) Cornell Vet 64, 117 Sullivan DC et al (1984) Virology 132, 352

Equid herpesvirus 4 (EHV-4) A species in the genus Varicellovirus. A major cause of acute respiratory disease in horses worldwide, most horses being infected during the first 2 years of life. Shown in 1981 to be distinct from EHV-1 by restriction endonuclease studies on the virus genome. Horses may become latently infected, and reactivation with virus shedding may then occur to infect young foals and so maintain the virus indefinitely in a population of horses. Acute disease is associated with fever, anorexia and profuse nasal discharge. In extreme cases the disease may become a fatal bronchopneumonia. A combined EHV-4/EHV-1 inactivated vaccine is available, and alternative recombinant-derived vaccine candidates are under investigation. Synonyms: equine herpesvirus 4; equine rhinopneumonitis virus; respiratory infection virus.

Crabb BS and Studdert MJ (1995) Adv Virus Res 45, 153

Studdert MJ (1981) Science 214, 562

equine adenovirus 2 (EAdV-2)

Equid herpesvirus 5 (EHV-5) A species in the genus Rhadinovirus. Following respiratory tract infection, causes a disease in horses which resembles infectious mononucleosis, with malaise, fever and enlarged lymph nodes followed by virus persistence in circulating leukocytes. The consequent loss of physical performance is a serious concern to the racehorse industry. The similarities to Epstein-Barr virus suggest that EHV-5 may best be classified with the gamma-herpesviruses, and this awaits further molecular characterization of the genome.

Synonym: equine herpesvirus 5.

Agius CT and Studdert MJ (1994) Adv Virus Res 44, 357

Browning GF and Studdert MJ (1989) J Gen Virol 68, 1441

equid herpesvirus 6 (EHV-6) A tentative species in the genus Varicellovirus. Isolated from vesicular lesions on the muzzle of a foal donkey and the external genitalia and udder of its dam. Restriction analysis of the genome DNA revealed a relationship to EHV-3, but the viruses are antigenically quite distinct. Synonym: asinine herpesvirus 1.

Browning GF et al (1988) Arch Virol 101, 183

Jacob RJ (1988) In Equine Infectious Diseases, vol. 5, edited by DG Powell. Lexington: University of Kentucky Press, p. 140

Equid herpesvirus 7 (EHV-7) A species in the genus Rhadinovirus. Isolated from the peripheral blood leukocytes of a healthy donkey by co-cultivation with equine fetal kidney cells. A betaherpesvirus that is distantly related to EHV-2 and EHV-5. The clinical and epidemiological significance is not known. Synonym: asinine herpesvirus 2.

Browning GF et al (1988) Arch Virol 101, 183

Equid herpesvirus 8 (EHV-8) A species in the genus Varicellovirus. Isolated from an EHV-1 seropositive donkey that was treated with corticosteroids for 3 days before nasal swabs were taken and inoculated into equine fetal kidney cells. The virus is genetically related to EHV-1, and is apparently an alphaherpesvirus of donkeys which causes acute respiratory disease followed by latent infection in the natural setting.

Synonym: asinine herpesvirus 3. Browning GF ei al (1988) Arch Virol 101,183

Equid herpesvirus 9 (EHV-9) A species in the genus Varicellovirus. Isolated from a captive gazelle, but zebras may be the primary host. Immunologically related to Equine herpesvirus 1. Synonym: gazelle herpesvirus.

Fukushi H ei al (1997) Virology 227, 34

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