Effect of the Fv-1 locus in vivo: host range pseudotypes of murine sarcoma virus

Fv-1-specific host-range pseudotypes of murine sarcoma virus (MuSV) were developed by rescue from nonproducer cells with N- or B-tropic leukemia viruses. The MuSV(B) and MuSV(N) pseudotype viruses were tested in vitro and were restricted specifically by the Fv-1 gene locus. When the pseudo-type viruses were tested in vivo in mice of specific Fv-1 geno-types, tumor induction was completely restricted in nonpermissive animals, including athymic nude mice, whereas tumors grew progressively in permissive animals. All tumors regressed in adult heterozygous mice, but not in adult athymic nude mice.