| mouse leukaemia viruses | Retroviruses of the murine leukaemia-sarcoma complex that produce leukaemia and sometimes lymphosarcomas in mice, including the Abelron, Gross, Moloney, Friend, and Rauscher strains of virus; they have been isolated from inbred mice having high incidence of spontaneous lymphoid leukaemia. (05 Mar 2000) |
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| positive strand RNA viruses | Class IV and VI viruses that have a single stranded RNA genome that can act as mRNA plus strand) and in which the virus RNA is itself infectious. Includes Picornaviridae, Togaviridae and Retroviridae. (18 Nov 1997) |
| helper viruses | Viruses which enable defective viruses to replicate or to form a protein coat by complementing the missing gene function of the defective (satellite) virus. Helper and satellite may be of the same or different genus. (12 Dec 1998) |
| sandfly fever group viruses | A group of viruses in the genus phlebovirus of the family bunyaviridae transmitted by the sandfly, phlebotomus papatasii, and causing a short febrile illness in humans. The sandfly fever sicilian virus, the type species of the phlebovirus genus, is not part of this group. (12 Dec 1998) |
| sandfly fever viruses | An unclassified serologic group of arboviruses morphologically like Bunyavirus but antigenically unrelated, transmitted by Phlebotomus papatasi (sandfly) and causing phlebotomus fever; there are 20 strains, including Icoarachi and Itaporanga. Synonym: pappataci fever viruses, sandfly fever viruses. (05 Mar 2000) |
| sarcoma viruses, avian | Species of avian type c retroviruses (retroviruses type c, avian) producing sarcomata and other tumours in chickens and other fowl and also in pigeons, ducks, and rats. (12 Dec 1998) |
| sarcoma viruses, murine | Species of replication-defective mammalian type c retroviruses (retroviruses type c, mammalian) which are capable of transforming cells, but which replicate and produce tumours only in the presence of murine leukaemia viruses (leukaemia viruses, murine). (12 Dec 1998) |
| sarcoma viruses, simian | Species of mammalian type c retroviruses (retroviruses type c, mammalian) producing tumours in primates. Originally isolated from a fibrosarcoma in a woolly monkey, ssv is a replication-defective v-onc virus which carries the sis oncogene. In order to propagate, ssv requires a replication-competent helper virus, simian sarcoma virus-associated virus (ssav). (12 Dec 1998) |
| satellite viruses | Defective viruses which can multiply only by association with a helper virus which complements the defective gene. Satellite viruses may be associated with certain plant viruses, animal viruses, or bacteriophages. They differ from satellite RNA (RNA, satellite) in that satellite viruses encode their own coat protein. (12 Dec 1998) |
| hepatitis c-like viruses | A genus of flaviviridae causing parenterally-transmitted non-a, non-b hepatitis (hepatitis c) which is associated with transfusions and drug abuse. Hepatitis c virus is the type species. (12 Dec 1998) |
| hepatitis viruses | Any of the viruses that cause inflammation of the liver. They include both DNA and RNA viruses as well viruses from humans and animals. (12 Dec 1998) |
| HTLV-blv viruses | Genus of the family retroviridae consisting of exogenous horizontally-transmitted viruses found in a few groups of mammals. Infections caused by these viruses include human b or adult T-cell leukaemia/lymphoma, and bovine leukaemia. (12 Dec 1998) |
| simbu group viruses | A group of viruses in the bunyavirus genus of the bunyaviridae family that are found in asia, africa, and the americas. (12 Dec 1998) |
| spleen focus-forming viruses | Murine leukaemia viruses that are replication-defective and rapidly transforming. The envelope gene plays an essential role in initiating erythroleukaemia, manifested by splenic foci, splenomegaly, and polycythemia. Spleen focus-forming viruses are generated by recombination with other viral types including friend p (polycythemia), friend a (anaemia), rauscher, and cas (from wild mice at lake casita, california). (12 Dec 1998) |
| nairobi sheep disease viruses | A group of viruses of the genus nairovirus, transmitted by the ixodid ticks and producing a lethal gastroenteritis in sheep and goats, especially in africa. Though major veterinary pathogens, their effect on humans has not been firmly established. (12 Dec 1998) |