| 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) |
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| 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) |
| 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) |
| defective viruses | Viruses which lack a complete genome so that they cannot completely replicate or cannot form a protein coat. Some are host-dependent defectives, meaning they can replicate only in cell systems which provide the particular genetic function which they lack. Others, called satellite viruses, are able to replicate only when their genetic defect is complemented by a helper virus. (12 Dec 1998) |
| swine influenza viruses | Strains of influenza virus type A which cause influenza of swine and can infect humans. (05 Mar 2000) |
| DNA tumour viruses | DNA viruses producing malignant tumours. Of the six major groupings of DNA viruses four contain members which are actually or potentially oncogenic: the adenoviridae, the herpesviridae, the papovaviridae, and the poxviridae. (12 Dec 1998) |
| DNA viruses | Viruses whose nucleic acid is DNA. (12 Dec 1998) |
| inclusion conjunctivitis viruses | Former name for Chlamydia trachomatis. (05 Mar 2000) |
| influenza viruses | Virus's of the family Orthomyxoviridae which cause influenza and influenza-like infections of humans and other animals; virus's included are influenza virus types A and B of the genus Influenzavirus, causing, respectively, influenza A and B, and influenza virus type C, which probably belongs to a separate genus and causes influenza C. (05 Mar 2000) |
| insect viruses | Viruses infecting insects, the largest family being baculoviridae. (12 Dec 1998) |
| oncogenic viruses | Viruses that produce tumours. (12 Dec 1998) |