Suppression of the temperature-sensitive character of adenovirus 12 early mutants in monkey cells transformed by an adenovirus 7-simian virus 40 hybrid

Temperature-sensitive mutants of adenovirus 12, defective in viral DNA replication, fall into three complementation groups; tsA, tsB and tsC. Each of these classes was temperature dependent for virus production, viral DNA synthesis and virion antigen in human embryonic kidney cells and in T22 cells, a monkey cell line transformed by defective particles of simian virus 40 (SV40). In H5 cells, a monkey cell line transformed by an adenovirus 7-SV40 hybrid, however, the tsB and tsC mutants were not temperature sensitive for viral replication while the tsA mutant retained its temperature-sensitive phenotype. Wild-type adenovirus 7, but not wild-type SV40, was able to complement tsA, tsB and tsC for either infectious virus production or DNA replication. These observations suggest that adenovirus 7-specific functions present in the H5 cells complement or suppress the tsB and tsC gene functions. DNA-DNA reassociation kinetics and DNA-RNA hybridization competition experiments have been performed and demonstrate the presence and the transcription of at least a portion of the adenovirus 7 genome in the H5 cells.