Friend murine leukemia virus FrMLV A

strain of Murine leukemia virus in the genus Gammaretrovirus, originally obtained from the leukemic spleen of a 14-month-old Swiss mouse which had been injected at birth with a cell-free extract of Ehrlich ascites carcinoma cells. Causes a disease not observed to occur spontaneously. Characterized by gross splenomegaly. Adult mice are susceptible and die of the disease in about 3-5 weeks, or longer in a few cases. A number of strains have been isolated: some cause hemorrhage into the spleen and death in 3 weeks, others cause foci of tumor cells in the spleen and a less acutely fatal disease. The virus preparations available appear to be a mixture of two viruses: (1) a lymphoid leukemia virus which does not produce the erythroleukemia typical of Friend virus; and (2) a replication-defective RNA tumor virus responsible for the leukemogenesis, designated spleen focus-forming virus (SFFV), which does not contain an oncogene, the active gene product of which is a deleted Env protein called gp55. Presence of the virus in non-producer cells may be detected by reverse transcriptase activity. The genome of SFFV consists of two sets of nucleic acid sequences: one homologous to part of the helper leukemia virus and the other specific to SFFV, but related to sequences in xenotropic mouse leukemia viruses. Rat passage or passage at endpoint dilution results in the separation of the lymphoid leukemia virus.

Kabat D (1989) Curr Top Microbiol Immunol 148,1 Steeves RA (1975) J Natl Cancer Inst 54, 289 Troxler DH et al (1978) J Exp Med 148, 639

Frijoles virus (FRIV) A species in the genus Phlebovirus; with Joa virus forms the Frijoles complex. Isolated from phle-botomine insects of Lutzomyia sp in the Canal Zone, Panama. Not reported to cause disease in humans.

Frijoles virus VP-161A (FRIV) An isolate of Frijoles virus.

fringilla papillomavirus A probable species in the genus Papillomavirus. Isolated from papillomas excised from the leg of a chaffinch, Fringilla coelebs. Virion diameter: 52nm; sedimentation coefficient: 300S; and density in CsCl: 1.34g/ml. Composed of 72 morphological units arranged in a skew T = 7d icosahedral lattice. The circular double-stranded genome measured 2.6|im. Protein composition similar to Human papillomavirus. Papillomas have only been found in two species of Fringilla: the chaffinch and the brambling, F. montif-ringilla.

Synonyms: avian papillomavirus; bird papillomavirus; chaffinch papillo-mavirus.

Osterhaus ADME et al (1977) Intervirology 8, 351

frog adenovirus (FrAdV-1) An unassigned species in the family Adenoviridae. Found in a culture of the turtle cell line TH-1 inoculated with cells from a granuloma-bearing kidney of a leopard frog, Rana pipiens. Replicated with CPE in turtle cells but not in cells from other reptiles, amphibia, fish or mammals. Optimal temperature for virus replication is 30°C. Does not have mastadenovirus group antigen: not neutralized by aviaden-ovirus antiserum. Does not cause tumors on injection into nephrogenic ridge of Rana pipiens tadpole. Agglutinates rat erythrocytes at 37°C.

Clark HF et al (1973) Virology 51, 392

frog herpesvirus 4 Synonym for ranid her-pesvirus 2.

Frog virus 3 (FV-3) The type species of the Ranavirus genus, family Iridoviridae. A member of the group of icosahedral cyto-plasmic deoxyviruses which infect amphibia. Enveloped virion has a diameter of 165-200nm. The icosahedral particle is 130-145nm in diameter. Replicates in both the nucleus and the cytoplasm. At optimal temperature of 23-26°C, multiplies in cells of all vertebrate classes in vitro. Envelope is acquired on budding through plasma membrane. Genome consists of one molecule of double-stranded DNA (170kb). G + C ratio 54%. Buoyant density (CsCl):

Fv1 gene

1.287g/ml. Lethal to tadpoles of several Rana and Bufo sp. In several toad species the virus produces hemorrhagic necrosis of kidneys and stomach. Replicates in adult newts but not in frogs. On infection, cellular nucleic acid synthesis is inhibited and viruses, such as Vaccinia virus, SV40 and several RNA viruses, that were in the process of replication in the cell when superinfection by FV-3 occurred have their replication halted, while FV-3 continues to replicate. In mice FV-3 does not replicate but causes acute degenerative hepatitis owing to this blocking of RNA synthesis.

Goorha RM and Granoff A (1999) In Encyclopedia of Virology, Second edition, edited by A Granoff and RG Webster. London: Academic Press, p. 582 Murti K et al (1985) Adv Virus Res 30, 1

frog virus 4 Synonym for ranid her-pesvirus 2.

FS (Family Study) virus A virus isolated from an outbreak of gastroenteritis during the course of the Family Study in Cleveland, USA. Could be passed in humans, and infection gave immunity to infection by Marcy virus. The strain has since been lost and can no longer be identified.

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