Analysis of translational products of Friend strain of spleen focus-forming virus

Abstract
Normal rat kidney cells nonproductively infected with the Friend strain of spleen focus-forming virus (SFFV) were analyzed for the presence of murine leukemia virus-specific type C viral proteins. SFFV coded for the p15 and p12 proteins of Friend-murine leukemia virus as determined by immunological typing of their antigenic determinants. Molecular-size analysis of p15 and p12 proteins in SFFV nonproductively infected normal rat kidney cells indicated that these proteins are translated as parts of polyprotein molecules. The apparent MW of the polypeptides bearing p12 antigenic determinants revealed the presence of translational products of the SFFV genome that could not be accounted for by known type C virus helper structural proteins.