Effects of Poliovirus 2Apro on Vaccinia Virus Gene Expression

• DOI: 10.1111/j.1432-1033.1995.849_a.x
• Publication Date: 2004-12-22T21:22:24Z
• Authors: Elena Feduchi; Rafael Aldabe; Isabel Novoa; Luis Carrasco
• Keywords: Gene Expression Regulation, Viral; 0301 basic medicine; Base Sequence; Transcription, Genetic; Blotting, Western; Molecular Sequence Data; Cytarabine; Antiviral Agents; Peptide Fragments; Cell Line; 3. Good health; Cysteine Endopeptidases; 03 medical and health sciences; Peptide Initiation Factors; Protein Biosynthesis; Animals; Humans; Amino Acid Sequence; RNA, Messenger; Cloning, Molecular; Carrier Proteins; DNA Primers; HeLa Cells

The effects of transient expression of poliovirus 2Apro on p220 cleavage in COS cells have been analyzed. When 2Apro was cloned in plasmid pTM1 and transiently expressed in COS cells, efficient cleavage of p220 occurred after infection of these cells with a recombinant vaccinia virus hearing phage T7 RNA polymerase. High numbers of COS cells were transfected with pTM1‐2A, as judged by p220 cleavage, thereby allowing an analysis of the effects of poliovirus 2Apro on vaccinia virus gene expression. A 40–50% cleavage of p220 by transfected poliovirus 2Rpro was observed ten hours post infection and cleavage was almost complete (80–90%) 20–25 hours post infection with vaccinia virus, Profound inhibition of vaccinia virus protein synthesis was detectable ten hours post infection and was maximal 20–25 hours post infection. This inhibition resulted from neither a blockade of transcription of vaccinia virus nor a lack of translatability of the mRNAs present in cells that synthesize poliovirus 2Apro. Addition of ara‐C inhibited the replication of vaccinia virus and allowed the continued synthesis of cellular proteins. Under these conditions, 2Apro is expressed and blocks cellular translation. Finally, p220 cleavage by 2Apro did not inhibit the translation of a mRNA encoding poliovirus protein 2C, as directed by the 5′ leader sequences of encephalomiocarditis virus. Therefore, these findings show a correlation between p220 cleavage and inhibition of translation from newly made mRNAs. Our results are discussed in the light of present knowledge of p220 function, and new approaches are considered that might provide further insights into the function(s) of initiation factor eIF‐4F.