Virion heat-sensitivity of adenovirus type 5 temperature-sensitive mutants and interferon induction

Kinetics of interferon induction with wild type adenovirus 5, and three temperature-sensitive mutants, ts 1, ts 18 and ts 19 were examined in chick embryo cells (CEC) at permissive (31 degrees C) and non-permissive (38 degrees C) temperatures. Interferon levels reached a maximum four days after infection with the wild type and all ts mutants at 31 degrees C. However, at 38 degrees C, ts 18 and ts 19 failed to induce interferon, while wild type and ts 1 induced normal levels which reached a maximum by three days after infection. Striking differences in virion heat sensitivities between wild type, ts 1, ts 18 and ts 19 at both 50 degrees C and 52 degrees C were detected. These results suggested that ts 18 and ts 19 might each have a mutation in a gene coding for a virion structural component. The production of infectious progeny by shift-up experiments on Hela cells showed that mutant ts 18 was affected immediately after shift-up at all times throughout the growth cycle. On the other hand, interferon production in CEC by mutant ts 18 was only affected by shift-up during the first five hours of incubation, which indicated involvement of an early gene function in elliciting interferon production.