Studies on Induction of Virus from Adenovirus and SV40 Hamster Tumors 2. "Helper" Viruses.

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Abstract
Summary Cell culture lines of virus-free hamster tumors which were initiated by ade-novirus 7 (Pinckney and Grider) or by adenovirus 18 and which synthesized “T” antigen were tested exhaustively for release of infectious adenovirus following addition of candidate “helper” viruses including SV40 respiratory syncytial virus and reovirus type 1. Attempts to detect adenovirus were by copropagation with susceptible indicator cells and by subculture of supernatant fluid or of disrupted cells in a sensitive assay cell system. In no case was infectious adenovirus recovered. The data permit speculation that the adenovirus genetic material retained in the tumor cells which was sufficient to code for “T” antigen might have been too highly integrated in the cell or might have been insufficient in amount to produce infectious virus. Alternatively, the “helper” viruses chosen might not have been appropriate to demonstrate the effect. Whatever the factors involved, it appeared quite clear that SV40, RS and reovirus 1 agents failed to afford sufficient or proper complementation or facilitation to effect release of infectious adenovirus from adenovirus 7 and 18 tumor cells of hamsters.