Monoclonal antibodies against simian virus 40 T antigens: evidence for distinct sublcasses of large T antigen and for similarities among nonviral T antigens

Abstract

Three clones of hybrid cells were isolated which synthesize antibodies specific for determinants on SV40 T antigens. Mouse myeloma NS1 cells were fused with spleen cells from mice immunized with SV40-transformed mouse cells. Hybrid cells were selected in HAT medium and cloned in soft agar. An enzyme-linked immunosorbent assay was used for detection and quantification of mouse antibodies against SV40 T antigens. Monoclonal antibodies from 3 of the 24 clones that scored as positive in the enzyme-linked immunosorbent assay were verified by immunoprecipitation to be specific for SV40 T antigens. Two clones (7 and 412) produced antibodies that recognized denaturation-sensitive antigenic determinants unique to large T antigen. Antibodies from clone 7 appeared to have a low affinity for large T antigen. Antibodies from clone 412 had a higher affinity for large T antigen but did not recognize a subclass of large T antigen that was recognized by tumor serum. Antibodies of the 3rd clone, clone 122, recognized a denaturation-stable antigenic determinant of the 53,000 dalton mouse nonviral T [tumor] antigen in SV40-transformed cells. Antibodies from clone 122 also recognized similar (51,000-56,000 dalton) nonviral T antigens in SV40-transformed or lytically infected cells from 5 mammalian species [human, mouse, rat, African green monkey and hamster] and in 4 uninfected mouse lines. The 94,000 dalton SV40 large T antigen may exist as immunologically distinguishable subclasses and the nonviral T antigens of 5 mammalian species share at least 1 antigenic determinant.