Use of UV irradiation to identify the genetic information of vesicular stomatitis virus responsible for shutting off cellular RNA synthesis.

UV irradiation of infectious vesicular stomatitis virus was employed to study the relationship between the expression of certain viral gene functions and viral inhibition of RNA synthesis in mouse myeloma (MPC-11) cells. Viral infectivity, protein synthesis, and viral mRNA synthesis were all highly susceptible to inactivation by UV radiation; however, low levels of viral transcriptase activity were detected in vitro in virus preparations subjected to large doses of UV radiation. In sharp contrast, the capacity of vesicular stomatitis virus to shut off cellular transcription was quite resistant to UV radiation. The data presented here indicate that viral transcription is essential to inhibit host RNA metabolism, even though synthesis of viral polypeptides in the inhibited cells could not be detected. At those levels of UV radiation that inactivated all viral gene functions, except viral inhibition of cellular RNA synthesis, the only viral product detected was non-adenylated, low-molecular-weight RNA species.