Identification of early proteins induced by highly oncogenic human adenovirus 12 during lytic infection and in hamster tumors

“Early” proteins (EP) induced by infection of cultured human KB cells with human adenovirus 12 (Ad12) were resolved by electrophoresis on sodium dodecyl sulfate (SDS)-polyacrylamide slab gels. Ad12 infected cells were incubated either in the presence of cycloheximide (CH) (to enhance the synthesis of early mRNA relative to cell mRNA) or cytosine arabinoside (ara C) (to prevent the expression of late viral genes) for 8 hr and the proteins were labeled with ${}^{35}\text{S}$] methionine (met) in an isotonic (110 mM NaCl) or hypertonic medium (210 mM NaCl) in the presence of ara C. Seven Ad12 induced EPs with apparent molecular weights of 60,000 (60K), 16.5K, 15K, 13K, 12.5K, 11K, and 10K (EP1 to EP7, respectively) have been identified when infected cells were labeled in an isotonic medium with CH pretreatment or in hypertonic medium with or without CH pretreatment. Sera from hamsters bearing Ad12 induced tumors (Ad12 T antisera) immunoprecipitated at least four of these polypeptides.