Antigenic Relationship Of Sv40 Early Proteins To Purified Large-T Polypeptide

Rabbit antiserum was produced against SV40 large T antigen purified by immunoprecipitation and SDS-polyacrylamide gel electrophoresis. This antiserum immunoprecipitated both large T and small t antigens, and reacted with SV40 T, U, and S antigens by immunofluorescence. these data establish the antigenic relatedness of all the known SV40 early gene products, with the exception of transplantation antigen activity, and confirm the virus-specific nature of each. The reactivity of the anti-T polypeptide serum was compared with the specificities of T-reactive antisera produced by different methods, including conventional tumor-bearing hamster sera, rabbit antiserum directed against whole-cell SDS-lysates of SV40-transformed rabbit kidney cells, and high-titer ascites fluid from hamsters in which ascites was induced by injection of SV40-transformed hamster ascites cells. Each of the antisera was reactive in all of the tests for SV40-induced early antigens, but the relative reactivity toward each protein varied considerably. It is postulated that the differences in reactivity to small t antigen and U antigen represent differences in the immune response of individual animals to the amino and carboxyl termini of the large T antigen polypeptide, respectively. Antiserum produced against the SDS-denatured large T polypeptide exhibited the highest reactivity to both small t and U antigenic sites relative to its reactivity against intranuclear large T antigen.