title: Identification of a spleen focus-forming virus in erythroleukemic mice infected with a wild-mouse ecotropic murine leukemia virus.
abstract: An NFS/N mouse inoculated at birth with an ecotropic murine leukemia virus (MuLV) obtained from wild mice (Cas-Br-M MuLV) developed a lymphoma after 18 weeks. An extract prepared from the lymphomatous spleen was inoculated into newborn NFS/N mice, and these mice developed erythroleukemia within 9 weeks. Spleens from the erythroleukemic mice contained ecotropic and mink cell focus-inducing (MCF) MuLVs; however, when these viruses were biologically cloned and reinoculated into newborn NFS/N mice, no erythroleukemia was induced. In contrast, cell-free extracts prepared from the erythroleukemic spleens induced erythroleukemia within 5 weeks. Analysis of cell-free extracts prepared from the erythroleukemic spleens showed that they contained a viral species that induced splenomegaly and spleen focus formation in adult mice, with susceptibility controlled by alleles at the Fv-2 locus. The spleen focus-forming virus coded for a 50,000-dalton protein precipitated by antibodies specific to MCF virus gp70. RNA blot hybridization studies showed the genomic viral RNA to be 7.5 kilobases and to hybridize strongly to a xenotropic or MCF envelope-specific probe but not to hybridize with an ecotropic virus envelope-specific probe. The virus described here appears to be the fourth independent isolate of a MuLV with spleen focus-forming activity.
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D005622:Friend murine leukemia virus / Q000235:genetics / Q000276:immunology; D009052:Leukemia Virus, Murine / Q000235:genetics / Q000276:immunology; D004915:Leukemia, Erythroblastic, Acute / Q000382:microbiology* / Q000473:pathology; D007942:Leukemia, Experimental / Q000382:microbiology* / Q000473:pathology; D051379:Mice; D012367:RNA, Viral / Q000032:analysis; D013154:Spleen / Q000382:microbiology / Q000473:pathology
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral