Functional suppression in mammalian cells of nonsense mutations in the herpes simplex virus thymidine kinase gene by suppressor tRNA genes

A nonsense mutation (UAG) in the thymidine kinase gene of herpes simplex virus type 1 can be suppressed in vivo to produce active thymidine kinase by prior infection with a defective simian virus 40 stock which acts as a vector to introduce a functional suppressor tRNA gene into mammalian cells in culture. The suppression is specific for UAG, but not UGA or missense, mutants and restores thymidine kinase activity to 20 to 40% of the wild-type level. These results suggest that many cell lines susceptible to simian virus 40 infection may be transiently converted to a suppressor-positive phenotype for use in the genetic study of mammalian viruses.