Abstract
AKR mice, which regularly contain infectious murine leukemia virus, were mated with four Fv-1n strains of mice which show little or no expression of virus. F1, F2, and first and second backcross generation hybrids were tested for virus in tail tissue at 2 and 6 wk of age. The segregation data indicate that the AKR mouse contains two unlinked, autosomal, chromosomal loci, either of which suffices to induce detectable levels of infectious virus in Fv-1n progeny by 6 wk of age. One of the loci (tentatively referred to as V1) is on linkage group I, 25–30 map units from the locus for albino; the gene order tentatively appears to be N1-c-Hbb.