IDENTIFICATION OF ENVELOPE PROTEIN RESIDUES REQUIRED FOR THE EXPANDEDHOST-RANGE OF 10A1 MURINE LEUKEMIA-VIRUS

The 10A1 murine leukemia virus (MuLV) is a recombinant type C retrovir us isolated from a mouse infected with amphotropic MuLV (A-MuLV). 10A1 and A-MuLV have 91% amino acid identity in their envelope proteins ye t display different host ranges. For example, CHO-K1 cells are resista nt to A-MuLV but susceptible to infection by 10A1. We have now determi ned that retroviral vectors bearing altered A-MuLV envelope proteins c ontaining 10A1-derived residues at positions 71 (A71G), 74 (Q74K), and 139 (V139M) transduce CHO-K1 cells at efficiencies similar to those a chieved with 10A1 enveloped vectors. A-MuLV enveloped retroviral vecto rs with these three 10A1 residues were also able to transduce A-MuLV-i nfected NIH 3T3 cells. This observation is consistent with the ability of vectors bearing this altered A-MuLV envelope protein to recognize the 10A1-specific receptor present on NIH 3T3 cells and supports the p ossibility that residues at positions 71, 74, and 139 of the 10A1 enve lope SU protein account for the expanded host range of 10A1.