A Radiobiological Study of the Replication of Newcastle Disease Virus and of Interferon Formationin Vitro

Abstract

In monkey kidney cells, the production of interferon induced by Newcastle disease virus is closely related to the viral multiplication. (1) The capacity (u.v.) of the viral production is highly radioresistant as compared with that of the interferon production. The latter is an exponential function for doses up to 500 ergs mm⁻². (2) The radiosensitivity of the viral production decreases during the lag time of its cycle. This phenomenon is blocked by puromycin but not by actinomycin D. (3) The radiosensitivity curve of the interferon production, similar to that of the sensitivity to actinomycin D, shows three steps: (a) between 1 and 4 hours after infection, there is the high radiosensitivity of cellular DNA which codes for the messenger RNA of interferon; (b) between 4 and 12 hours the radiosensitivity decreases; (c) and reaches a plateau after 12 hours. Various experimental data suggest that this very low radiosensitivity is a measure of the sensitivity of the ribosomal process of the interferon formation.