Translation of both 5'TOP and non-TOP host mRNAs continues into the late phase of Baculovirus infection.

Complete cDNA sequences were obtained for ribosomal protein (rp) L15 and eukaryotic initiation factor eIF2alpha from the lepidopteran insect Spodoptera frugiperda, and for elongation factor eEF2 from S. exigua. The presence of a 5' terminal oligopyrimidine (TOP) tract classified the lepidopteran rpL15 transcript as a TOP mRNA. For eEF2, two types of transcripts were observed, one of which had a 5'TOP tract. The transcript levels for rpL15, eEF2 and eIF2alpha decreased following baculovirus infection. Polysome analysis showed that the corresponding mRNAs remained to be translated until at least 16 h post-infection for both TOP and non-TOP mRNAs. Baculovirus-induced host shut-off therefore appears to be regulated at the level of RNA abundance rather than at the translational level.