Abstract
NB tropic Friend murine leukemia virus (F-MuLV) replicates equally well in BALB/c and C57BL mice inoculated as neonates but causes almost exclusively erythroblastosis in BALB/c mice and nonerythroid (lymphoid and myelogenous) leukemias in C57BL mice. The C57BL resistance to erythroblastosis appears to be controlled by a single dominant gene in first and second backcrosses to BALB/c. This resistance to erythroblastosis is distinct from other genes known to affect susceptibility to Friend virus including Fv-1, Fv-2, H-2, Rfv-3, Fv-4, and Rmcf. We suggest the name Fhe for the new gene controlling susceptibility to Friend helper virus erythroblastosis.