Temporal regulation of the rate of vesicular stomatitis virus mRNA translation during infection of Chinese hamster ovary cells

Vesicular stomatitis virus (VSV) mRNAs on polysomes 3 hr after infection are not translated in vivo as efficiently as mRNAs 2 hr after infection. There are 14?, 12?, 11?, and 8-fold increases in the amounts of L, G, N, and M messengers, respectively, on polysomes between 2 and 3 hr after infection. However, there are only 3?, 5?, 3?, and 4-fold increases in the rates of synthesis of the respective proteins. The in vivo translational efficiences of these messengers, which is a measure of their capacity to act as template for protein synthesis, are therefore lower at 3 hr after infection than at 2 hr. Since the mRNAs isolated 3 hr after infection are as active in a wheat germ cell-free protein synthesizing system as the mRNAs isolated at 2 hr, the decreased efficiency of VSV translation in vivo at 3 hr is not due to changes in mRNA primary structure. The observed difference is more likely due to a reduced efficiency of the host cell translational system to translate VSV mRNA at 3 hr relative to 2 hr. It was found that at 2 hr after infection, the majority of VSV mRNA is not associated with polysomes, but at 3 hr, the majority of viral messages is polysome bound.