Adenovirus late protein synthesis is resistant to the inhibition of translation induced by poliovirus.

Inhibition of host protein synthesis after poliovirus infection has been suggested to be a consequence of the proteolytic degradation of a p220 polypeptide necessary to translate capped mRNAs. However, the synthesis of several adenovirus late proteins on capped mRNAs was resistant to poliovirus inhibition. Thus, the hexon protein was still made 8 h after poliovirus superinfection. The synthesis of other adenovirus proteins such as the fiber was much more sensitive to poliovirus-induced inhibition than the hexon, either in the absence or in the presence of guanidine. Detailed densitometric analyses clearly showed the differential behavior of several adenovirus late mRNAs to poliovirus shut-off of translation. This is striking in view of the fact that a common leader sequence in the 5' termini is present in the adenovirus late mRNAs. The use of 3-methyl quercetin, an inhibitor of poliovirus RNA synthesis (Castrillo, J. L., Vanden Berghe, D., and Carrasco, L. (1986) Virology 152, 219-227), showed that translation of several capped adenovirus mRNAs took place in poliovirus-infected cells after the synthesis of host proteins had ceased. The poliovirus mRNA and the adenovirus mRNA coding for the hexon protein are very efficient mRNAs and have a leader sequence of more than 740 and 250 nucleotides, respectively, with very rich secondary structures making it difficult to predict how the scanning model will operate on these two mRNAs.