Interferon production in L929 cells under impaired translational conditions: comparison of rates of interferon, actin, Newcastle disease and encephalomyocarditis viruses mRNAs initiation of protein synthesis

Abstract

The pattern of Interferon (IFN) production in virus-infected cells has been compared with the rate of bulk cellular protein synthesis, on one hand, and with the synthesis of representative cell and virus proteins such as actin, the gamma and the NP proteins of encephalomyocarditis (EMC) and Newcastle Disease (NDV) viruses, on the other hand. This was investigated under conditions of impaired protein synthesis such as i) high osmolarity media, ii) a virus-induced shut-off, and iii) in cells exposed to relatively low doses of cycloheximide (CXM), which slow elongation of protein chain and thus favour the translation of low-affinity messenger RNAs (mRNAs). In each instance IFN production was compared with 35S-methionine incorporation into TCA-precipitable materials and into SDS-polyacrylamide gel-analysed proteins. Data obtained from each of the experimental approaches all indicate that IFN production and cellular protein synthesis are modified in a closely related fashion suggesting that their mRNAs share a similar degree of affinity for ribosomes. Conversely, two mRNAs coding for representative EMC and NDV virus proteins exhibit, respectively, the highest and the lowest affinity for ribosomes as compared to actin mRNA.