Fv-4: gene controlling resistance to NB-tropic Friend murine leukemia virus. Distribution in wild mice, introduction into genetic background of BALB/c mice, and mapping of chromosomes.

A gene controlling resistance to NB-tropic Friend murine leukemia virus (F-MuLV) was studied in wild mice. Mice of various subspecies were crossed with inbred BALB/c mice, and their F1 hybrids were tested for resistance to F-MuLV. Some mice of Mus musculus molossinus (Japan), M. musculus castaneus (Taiwan and the Philippines), and M. musculus urbanus (Sri Lanka) appeared to have a dominant resistance gene. A partially congenic strain, BALB/c-Fv-4wr (C4W), was established by the introduction of the gene Fv-4wr from a M. musculus molossinus into the genetic background of BALB/c mice. [(C4W X DBA/2) X C57BL/6-Fvs] crosses revealed that Fv-4wr is located on chromosome 12 with the gene order of Fv-4w-Pre-1-lgh-1, apparently at the same site as the Fv-4. The resistance of C4W mice was indistinguishable from the Fv-4-controlled resistance of FRG mice.