The isolation and identification of the adenovirus group C tumor antigens

Abstract

Monkey or human cells infected with type 5 adenovirus were labeled with [ 35S]methionine at early or late times after viral infection. Two independently derived preparations of antisera (14b and Adl-SV40) from hamsters bearing group C adenovirus-induced tumors were employed to immunoprecipitate the viral-induced antigens found in adenovirus-infected cells. The specific immunoprecipitates were analyzed by SDS-polyacrylamide gel electrophoresis to determine the molecular weights of the adenovirus-infected cell antigens that reacted with the antibody from these sera. One antiserum preparation (14b) immunoprecipitated predominantly a single protein of 58,000 MW. No homologous protein was detected in uninfected cells and normal hamster serum failed to immunoprecipitate this antigen from infected cell extracts. The second antisera (Adl-SV40) specifically immunoprecipitated this 58,000 MW protein and in addition reacted with viral-specific antigens of 72,000 and 44,000 MW. All three of these viral-specific proteins (72,000, 58,000, and 44,000 MW) were synthesized at early times after viral infection prior to the start of viral DNA replication. The 72,000 and 58,000 MW antigens could be labeled with either [ 35S]methionine or inorganic [ 32P]phosphate. At late times after viral infection, the Adl-SV40 serum immunoprecipitated or coprecipitated a 120,000 MW protein. The 72,000 MW protein was shown to be immunologically related to the adenovirus single-strand specific DNA binding protein. Some or all of the 44,000 MW protein resulted from the proteolytic breakdown of the 72,000 MW protein. The adenovirus type 5 transformed cell line 14b contained the left-hand 40% of the adenovirus genome. In this cell line only the left-hand 7% of the genome was transcriptionally active [ Flint, S. J., Sambrook, S., Williams, J. F., and Sharp, P. A. (1976). Virology 72, 456–470]. The early adenovirus genes carried in the 14b DNA segment are common to all adenovirus-transformed cell lines. Thus it is likely that the 58,000 MW protein found in adenovirus-infected cells is an adenovirus-specific tumor antigen common to all tumors and transformed cells.