GA391 virus A strain of Lassa virus in the genus Arenavirus.

G protein Name used for the major glyco-protein of a number of viruses, especially negative-strand viruses.

Gabek Forest virus (GFV) A tentative species in the genus Phlebovirus, belonging to the sandfly fever virus group. Isolated from the spiny mouse, Acomys cahirinus (albigena). The vector species has not yet been determined.

Gadget's Gully virus (GGYV) An unas-signed tick-borne species in the genus Flavivirus. Isolated from ticks, Ixodes (Ceratixodes) uriae on Macquarie Island, Australia. Not known to cause disease in humans.

gag gene (group-specific antigen gene) One of the genes in the genome of retroviruses. Codes for the precursor of all the major internal antigens of the virus.

gag-pol gene The adjacent gag and pol genes of retroviruses are expressed from the full-length unspliced mRNA molecules, but only the gag gene is expressed unless a frameshift occurs into the pol open reading frame. This happens at a frequency of about 1 per 100 translation events, so the amount of pol precursor represents only 1% of the gag precursor that is synthesized.

gal1-gal2 Serotype designation given to the fowl adenovirus 1 isolated from the fowl, Gallus domesticus.

gal virus Synonym for gallus adeno-like virus, an Aviadenovirus.

galactosyl ceramide A cell surface molecule that has been proposed as an alternative to CD4 as a receptor for HIV-1 virus, particularly for entry into brain cells.

Harouse JM et al (1991) Science 253, 320

Galibi virus An unclassified virus isolated from Culicine mosquitoes in the Amazon region of Brazil. Not known to cause disease in humans.

Gallid herpesvirus 1 (GaHV-1) The type species of the genus 'Infectious laryngo-tracheitis-like viruses'. A widespread natural infection of fowls and pheasants, causing hemorrhagic tracheitis with gasping and coughing. Mortality up to 70%. A less virulent strain in Australia and USA causes only coughing and sneezing. Ducks, pigeons and turkeys are occasionally infected. No infections of mammals reported. Transmission via the respiratory route; some recovered birds may excrete virus for long periods. An egg- or cell-culture passage strain can be used as a live vaccine, administered orally in the drinking water. Synonyms: phasianid herpesvirus 1; avian infectious laryngotracheitis virus; infectious laryngotracheitis virus.

Gallid herpesvirus 2 (GaHV-2) The type species of the genus 'Marek's disease-like viruses'. A natural infection of fowls, pheasants, turkeys, quails, ducks, swans, geese, pigeons and budgerigars, causing progressive paralysis, usually in birds aged 2-8 months. The neuropathogenic form of the disease was first described by Jozsef Marek in 1907, hence the name Marek's disease virus, now reserved for the genus name. Causes a neoplastic lymphoprolif-erative disease of domestic chickens characterized by mononuclear cell infiltration and the development of lymphomas, principally in the peripheral nerves and visceral organs. It has been recognized as a major cause of economic loss to the poultry industry. It is the first common naturally occurring neoplastic disease in any species to be controlled by vaccination, and is the first example of an oncogenic herpesvirus. There are obvious similarities between MDV, the Epstein-Barr herpesvirus of humans and oncogenic herpesviruses of various animal species. A member of the subfamily Alphaherpesvirinae of the family

Gallid herpesvirus 2 (GaHV-2)

Herpesviridae. The genome DNA is 178 kb in length encoding 103 proteins. Meleagrid herpesvirus 1 is an antigenically related but non-pathogenic herpesvirus of turkeys (HVT) belonging to the same genus, which can transactivate latent Marek's disease virus genes in quail fibroblast cells. Marek's disease virus is cell-associated, but free virus is released from feather follicles and infection is spread by dust and oral secretions. It can be cultivated in chicken kidney cell cultures with production of plaques, but the virus remains cell-associated. Control is by vaccination of chicks at hatching with live herpesvirus of turkeys (Gallid herpesvirus 3) which establishes a permanent infection that prevents lymphoma formation. Since the introduction and widespread use of live vaccines, an acute form of the disease has appeared in Europe and America, characterized by enlargement and lymphocytic infiltration of the liver and other viscera, rather than the nervous system. Synonyms: fowl paralysis virus; Marek's disease herpesvirus 1; neurolymphomato-sis of fowls virus; phasianid herpesvirus 2.

Calnek BW et al (1998) Avian Dis 42, 124 Lee L et al (2000) Proc Natl Acad Sci 97, 6091 Payne LN (1999) In Encyclopedia of Virology, Second edition, edited by A Granoff and RG Webster. London: Academic Press, p. 945 Tulman ER et al (2000) J Virol 74, 7980 Yamaguchi T et al (2000) J Virol 74,10176

Gallid herpesvirus 3 (GaHV-3) A species in the genus 'Marek's disease-like viruses'. A cell-associated virus antigenically related to Gallid herpesvirus 2, and isolated from turkeys. Non-pathogenic in chickens. Does not cause neoplastic transformation. Replicates in avian cell cultures but, with the exception of hamsters, not in mammalian tissues. It protects fowls against Marek's disease. The virus is not released from the feather follicles so horizontal spread does not occur. The FC-126 strain is commonly used as the vaccine for chickens, and het-erologous antigens have been introduced to extend the usefulness of the vaccine (e.g. NDV, IBDV).

Synonym: Marek's disease herpesvirus 2. Alfonso CL et al (2001) J Virol 75, 971

gallus-adeno-like virus A strain of Fowl adenovirus D in the genus Aviadenovirus.

Originally isolated from chicken cell cultures during attempts to isolate chicken leukosis sarcoma virus. Replicates with typical adenovirus CPE in chicken cell cultures. In eggs causes the death of the embryo. Not apparently associated with spontaneous clinical disease but on inoculation into chicks causes liver necrosis. Antibodies are common in chickens. Synonym: GAL-1 virus.

Aghakhan SM (1974) Vet Bull 44, 531

GALV See Gibbon ape leukemia virus.

Gamboa virus (GAMV) A species in the genus Bunyavirus. With Maru 10962, Pueblo Viejo and 75V-2621 viruses forms the Gamboa serogroup. Isolated from the mosquito, Aedeomyia squamipennis, in Panama. A similar virus has been isolated in Surinam from mosquitoes of Aedes sp. Not reported to cause disease in humans.

gammaglobulin A fraction of serum proteins with antibody activity.

Gammaherpesvirinae A subfamily of the family Herpesviridae. The viruses replicate in lymphoblastoid cells, and some species will also replicate in epithelioid and fibroblastic cells, causing cell lysis. They are specific for either B or T lymphocytes. In lymphocytes replication is often incomplete with persistence of the viral genome but with minimal expression. Even when replication has caused cell death, little or no complete virus may be produced. Latent virus is frequently demonstrable in lymphoid tissues. Several species are associated with tumor formation. Host range narrow, usually limited to species in the same order as the natural host. There are two genera: Lymphocryptovirus (type species Human herpesvirus 4) and Rhadinovirus (type species Saimiriine herpesvirus 2). Synonym: lymphoproliferative herpes-virus group.

gamma interferon A class of interferon (known as 'immune interferon') that is produced by lymphoid cells in response to mitogens and by sensitized T lymphocytes in response to specific antigen. It is a lymphokine that plays a protective role in response to infection by upregulating cytokines such as interleukin 2 in T cells and tumor necrosis factor (TNF) in monocytes.

Guidotti LG and Chisari FV (2000) Virology 273, 221

Gammaretrovirus A genus in the family Retroviridae. The type species is Murine leukemia virus (MLV). Virions have a C-type morphology and a centrally located condensed core. Capsid assembly occurs at the inner surface of the membrane coincident with the budding process. The diploid genome is about 8.3 kb in size (one monomer) with an LTR about 600 bases long. There are four genes in the order gag-pro-pol-env. Both exogenous and endogenous viruses are found in many mammalian species, and reptilian and avian (reticuloendotheliosis) types are also known. There are also many replication-defective viruses that have acquired distinct cell-derived oncogenes belonging to the genus. The genus embraces the leukemia- and sarcoma-producing viruses and a number of related viruses which are probably non-oncogenic. Viruses spontaneously shed by infected cells are called 'exogenous viruses' but in addition there are 'endogenous viruses' whose genetic material is integrated into the cell genome and is vertically transmitted. The nucleic acid sequences of endogenous viruses hybridize with DNA from normal tissue cells. The degree of hybridization with different species of host can indicate the evolutionary origins of the virus. These endogenous viruses may become activated in vivo or in vitro, spontaneously or by various chemical or physical agents, and produce virus particles which may be ecotropic or xenotropic or amphotropic. The role of endogenous viruses in the production of spontaneous tumors is not yet clear. The genus is divided into three groups containing species isolated from mammals, reptiles and birds: mammalian virus group, reptilian virus group and avian (reticuloendotheliosis) virus group, respectively. There are type-specific or subgroup-specific glycoprotein antigens associated with the viral envelope and group-specific (gs) polypeptide antigens associated with the virion core: gs-1 antigen is shared by viruses from one species and is species-specific, but does not cross-

react with type B viruses; and gs-3 antigen is shared by all mammalian type C oncoviruses. Members of the genera Alpharetrovirus and Betaretrovirus do not have such interspecies gs-3 antigens.

Coffin JM (1992) In The Retroviridae, vol. 1, edited by JA Levy. New York: Plenum Press, p. 19

ganciclovir (GCV) 9-(1,3-dihydroxy-2-propoxy) methylguanine A derivative of acycloguanosine that is phosphorylated by an enzyme (product of the CMV UL97 gene) encoded by human cytomegalovirus (HHV-5) and is a potent inhibitor of cytomegalovirus replication. Used for treatment of retinitis and other complications of cytomegalovirus disease in immunosuppressed patients.

Crumpacker CS (1996) New Engl J Med 335, 721

Gan Gan virus (GGV) An unassigned virus in the family Bunyaviridae, serolog-ically a member of the group 3 virus group. Isolated from mosquitoes, Aedes vigilax, in Nelson Bay, Australia. Associated with an acute epidemic poly-arthritic-like illness in humans.

Ganjam group viruses A term no longer in use. The two viruses that it contained: Ganjam and Dugbe, are now placed in the Nairobi sheep disease serogroup of the Nairovirus genus, and Ganjam is now regarded as a strain of Nairobi sheep disease virus.

Ganjam virus A strain of Nairobi sheep disease virus in the genus Nairovirus isolated from ticks of Haemaphysalis sp in India.

Garba virus (GARV) An unassigned vertebrate rhabdovirus. Isolated from birds in Central African Republic. Not reported to cause disease in humans.

Gardner-Arnstein feline sarcoma virus (GAFeSV) A species in the genus Gammaretrovirus. See Feline leukemia virus.

Garissa virus (GAV) A probable species in the genus Bunyavirus, isolated from some human cases of hemorrhagic fever in Kenya and Somalia during an outbreak of Rift Valley fever in 1998. Sequence analysis showed that the virus is a reassortant with S and L genome segments of Bunyamwera virus and an M segment from an unknown source.

gasping disease virus Synonym for avian infectious bronchitis virus. Not to be confused with infectious laryngotracheitis virus (Gallid herpesvirus 1).

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