Cellular expression of murine leukemia virus gp70-related antigen on thymocytes of uninfected mice correlates with Fv-4 gene-controlled resistance to Friend leukemia virus infection.

Alleles at the Fv-4 locus have been shown to determine susceptibility (Fv-4s) and resistance (Fv-4r) to infection with ecotropic murine leukemia viruses (MuLV). The resistance is dominant in heterozygous mice. BALB/c mice are Fv-4ss and a semicongenic line BALB/c-Fv-4wr, homozygous for Fv-4r allele and called C4W, is being developed. Extracts of 125I-labeled thymocytes from BALB/c and C4W mice were precipitated by a series of antisera against MuLV and the precipitates examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Thymocytes from C4W mice expressed 80K and 73K glycoproteins related to the gp70 of MuLV, while only the 73K glycoprotein was occasionally detectable on BALB/c thymocytes. Genetic studies showed that a locus controlling expression of the 80K protein was dominant and associated with the resistant allele at Fv-4. This membrane gp70 may be important in the Fv-4-mediated resistance to exogenous virus infection.