Comparison of initiation rates of encephalomyocarditis virus and host protein synthesis in infected cells

Abstract

The relative initiation rates for encephalomyocarditis virus mRNA and host mRNA's in infected cells were measured using two independent techniques. In both cases the results showed that viral mRNA initiates at a much higher rate than host mRNA'S. This difference was observed midway in the infectious cycle, well before virus-induced cytopathic effects (leakage of low-molecular-weight metabolites, failure to exclude trypan blue) were apparent. These results confirm that encephalomyocarditis viral mRNA is a more efficient initiator than host mRNA's in vivo, as has previously been demonstrated in in vitro experiments.

Induction and/or selective retention of proteins in mammalian cells exposed to cycloheximide

“…Moreover, Lodish (1971) demonstrated that graded low doses of the drug are able per se to descriminate among mRNAs with different affinities for the biosynthetic machinery of the cell. Preferential translation of viral vs. cell mRNAs in cells exposed to low doses of the drug has been determined (Jen et al, 1978). Similar data have been obtained in studies on the regulation mechanisms in heat-shock response.…”

Cellular mRNA translation is blocked at both initiation and elongation after infection by influenza virus or adenovirus

“…The selectivity at the initiation step may involve, at least in part, competition between the viral and cellular mRNAs for limiting components of the translational machinery, presumably mainly initiation factors (8,20,35,56). Several types of competition could play a role.…”

Regulation of Protein Synthesis in Virus-Infected Animal Cells

“…In contrast with reovirus and VSV, the concentration of EMC virus mRNA in infected cells may be too low for simple competition to effect the observed switch from host to viral translation, even though EMC mRNA is translated more efficiently than host mRNAs both in uiuo (Jen et al, 1978) and in vitro (Golini et al, 1976;Svitkin et al, 1978). In view of the overall decline in translation that begins 3 hours postinfection, however, the idea that EMC virus mRNA outcompetes host mRNAs for the low, residual translational capacity seems reasonable.…”