Host range differences among xenotropic type C retroviruses isolated from mouse kidney cell cultures

By co-cultivation procedures, infectious xenotropic type C viruses have been recovered from kidney cells of several strains of mice. They have host-range patterns which place them into separate subgroups. In cells cultivated from one NZB kidney, two biologically different xenotropic type C retroviruses were found. One, X-NZB/K-1, infects and replicates well in human and mink fibroblast cells but does not induce foci in mink S + L - cells with good efficiency. The other, X-NZB/K-2, infects and replicates well in mink but not human fibroblast cells, and induces foci readily in mink S + L - cells. Cross-infection studies indicate that these viruses, classified as xenotropic by host range and envelope properties, are genetically stable.