In vivo and in vitro TSTA-inducing activity of temperature-sensitive (ts) mutants of SV40.

In vivo TSTA induction in Syrian hamsters was studied with the use of SV40 ts mutants (A, B, C, BC and D). The ts A30, TS A239 and possibly also the ts BC210 mutants were defective in resistance-inducing activity in hamsters in contrast to wild type SV40 and other ts mutnats. At the permissive temperature ts A30 and ts A239 did not induce TSTA in hamster cells during abortive infection in vitro, while they did so in green monkey cells at both permissive and non-permissive temperatures. In hamster cells transformed by ts A30, ts A239 and ts A209 mutants none at all or very little TSTA was detected by in vivo transplantation immunological tests. Thus, expression of TSTA induced by these three SV40 ts A mutants was found to be dependent from the species of infected cells and was being a temperature independent viral function.