Post-transcriptional Controls in Virus-infected Cells

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Eukaryotic gene expression is regulated at transcriptional, post- transcriptional, and translational levels. Although the importance of transcriptional, mechanisms is understood, the role of post- translational controls is only beginning to be elucidated. Several observations suggest that the iridovirus, frog virus 3 (FV3), may be an excellent model in which to study post-transcriptional/ translational gene regulation: (a) the steady state level of FV3 early messages does not decline in infected cells, whereas host transcripts are rapidly degraded; (b) FV3 messages are translated more efficiently than host or heterologous messages in vitro; (c) early mRNA is not degraded and, after extraction, actively directs protein synthesis in vitro; and (d) late viral messages, which are major gene products in vivo, are translated poorly in extracts from uninfected cells. Taken together these phenomena suggest that FV3 gene expression is controlled, at least in part, at the post- transcriptional/translational level. %%% In this proposal, the nature of putative post transcriptional/ translational controls will be explored. To accomplish this, two specific aims have been established. Sp. Aim whether the expression of FV3 genes is regulated at the translational level by cis-acting mRNA control sequences and/or trans-acting mRNA-binding proteins. Sp. Aim nucleotide sequence of a representative panel of FV3 immediate early, early, and late mRNAs and ascertain whether viral messages possess unique regulatory signals that control translational efficiency. successfully completed these studies will provide important information on the mechanisms of virus-mediated translational control and on the cis and trans elements that regulate viral protein synthesis. In addition, these studies will extend our understanding of translational control mechanisms in eukaryotic systems.