Conditions for the Production of an Interferon Appearing in Chick Cell Cultures Infected with Sindbis Virus

Abstract

A viral inhibitor with the properties of interferon appeared in the fluids of chick cell cultures inoculated with a rapidly cytocidal agent-Sindbis virus. It was found that an important condition for the optimal production of this inhibitor was preincubation of the culture from which it was derived with heat inactivated virus. The inhibitor itself did not potentiate its production. Inactivated virus alone produced no inhibitor although it imparted minimal cell resistance. Interferon production was followed along with infective virus production under conditions close to synchronous infection. Apparently, synthesis of both products took place in the same cells but inhibitory activity was detectable slightly later than infectivity.