Isolation and characterization of two group-specific antigens from feline leukemia virus

Analytical polyacrylamide gel electrophoresis of feline leukemia virus revealed three major protein components, termed EI, EII, and EIII in order of decreasing electrophoretic mobility. Molecular weights of about 15,000, 18,000 and 33,000, respectively, have been found for these proteins. In comparative experiments, mouse leukemia virus (Rauscher) showed a similar electrophoretic pattern, but avian leukemia virus (AMV) a clearly different one. From feline leukemia virus, materials were isolated that behaved electrophoretically like EI and EIII. The EI isolate was characterized serologically as a group-specific (gs) antigenic component, which has thus far been found only in feline leukemia and feline sarcoma viruses. It is termed “gs-spec. antigen.” The EIII protein represents a gs-antigen which occurs in leukemia viruses of other mammalian species as well. It is designated “gs-interspec. antigen.”