African Rift Valley fever virus See Rift Valley fever virus

African swine fever virus (ASFV) Only member of the genus Asfivirus. The genome has double-stranded DNA, about 170-200 kb, depending on the isolate. The DNA is linear, covalently closed-ended with inverted complementary tandem repeats and is infectious. Causes a fatal disease resembling classic swine fever in domestic pigs (Sus scrofa domesticus). There is high fever, cough and diarrhea. Incubation period 7-9 days. Virus replication begins in the tonsils but soon becomes generalized: especially involved are lymph nodes and spleen. Surviving pigs may have viremia for months. Natural hosts are domestic and wild swine (Sus scrofa), warthogs, bush pigs and giant forest hogs. Infection is by contact and fomites. Premises may be infective for months. Virus has been recovered from argasid ticks, especially Ornithodorus moubata in East Africa and O. erraticus in Spain and Portugal, and replication in the ticks demonstrated. Virus diameter is

200nm; envelope is acquired as it buds through the plasma membrane. Survives dry at room temperature for years. Resists inactivation by some disinfectants but inactivated by 1% formaldehyde in 6 days, 2% sodium hydroxide in 24 days. Chloroform- and ether-resistant. Replicates in the chick embryo yolk-sac killing the embryo, and in cell cultures of swine macrophages, such as pig bone marrow. Hemadsorption of pig erythro-cytes is seen after 24 h and CPE later. After 100 passes the virus loses virulence for pigs but does not give protection from infection with virulent virus. Antibodies do not provide immunity. Originally observed in East, South and West Africa, the virus reached Portugal and Spain in 1957, France in 1964, Italy in 1967 and Cuba in 1971. Outbreaks occurred in Malta, Sardinia and Brazil in 1978, and Haiti in 1979. In 1982 a severe outbreak occurred for the first time in West Africa. The disease is believed to have been eradicated from Europe (except Sardinia) since 1995. In Brazil the disease is mild and has been difficult to eradicate. Sporadic outbreaks have occurred in and been eradicated from Cuba, the Dominican Republic and Haiti. Probably infection can be spread by waste food from ships and aeroplanes. No vaccine is available. Synonyms: wart-hog disease virus; maladie de Montgomery virus.

Andres G et al (1997) J Virol 71, 2331 Dixon LK et al (1993) Arch Virol Suppl 7, 185 Dixon LK et al (1994) J Gen Virol 75, 1655 Salas ML (1999) In Encyclopedia of Virology, Second edition, edited by A Granoff and RG Webster. London: Academic Press, p. 30 Yanez RJ et al (1995) Virology 208, 249

AG80-663 virus (AG80V) A species in the genus Alphavirus, antigenically related to Venezuelan equine encephalitis virus, but genetically distinct.

AG83-1746 virus (AG83-1746) An isolate of Maguari virus, in the genus Bunyavirus belonging to the Bunyamwera serogroup. Isolated from mosquitoes, Psorophora varinervis.

Mitchell CJ et al (1987) Am J Trop Med Hyg 36, 107

AG83-497 virus (AG497V) An isolate of Melao virus, in the genus Bunyavirus

Aino virus (AINOV)

belonging to the California serogroup. Isolated from mosquitoes, Culex sp.

Mitchell CJ et al (1987) Am J Trop Med Hyg 36, 107

agar A mixture of polysaccharides, some anionic, extracted from red algae, that forms a gel at temperatures below about 40°C. Used as a support medium when supplemented by appropriate buffers/ media ingredients for electrophoresis, production of microbial cultures, overlaying tissue culture cells, etc.

agarose A sulfate-free neutral fraction of agar. Often used in preference to agar as it does not contain inhibitors of virus growth frequently present in agar, and as lower temperature gelling products of agarose are now available. Also used widely in gel electrophoresis as the pore size is more uniform than that of agar.

agarose gel electrophoresis Technique used for separating proteins or nucleic acids by passage of an electric current through the gel.

age-dependent polio-encephalitis of mice virus Synonym for Lactate dehydrogenase-elevating virus.

agglutination test Some viruses will cause clumping of cells due to attachment to more than one cell and this can be used as the basis of an assay. Hemagglutination of red blood cells by influenza virus is an example. Cells other than red blood cells also exhibit the phenomenon. Also used to refer to the clumping of inert particles, e.g. latex, coated with antibody and mixed with homologous virus antigens.

agnoprotein A late protein encoded by SV40 and related viruses (BK and JC polyomaviruses) in the leader region of late mRNA. Function unknown.

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