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The role of poxvirus decapping enzymes

Tuesday, October 09, 2012 — Poster Session I

1:00 p.m. – 3:00 p.m

Natcher Conference Center, Building 45




  • S.W. Liu
  • B. Moss


All cellular and most viral mRNAs have a 5’-methylated cap structure that protects mRNA from hydrolysis by exonucleases and enhances translation. Vaccinia virus(VACV), a member of the poxvirus family, replicates in the cytoplasm and encodes a capping enzyme and polymerases for mRNA synthesis. Remarkably, VACV encodes decapping enzymes, D9 and D10, that can destabilize both viral and host cell mRNAs. Both D9 and D10 deletion mutants are viable. However, each of these mutants still contains one functional decapping enzyme that could compensate for loss of the other. To test this hypothesis, a panel of mutant VACVs(D9mu, D10mu and D9muD10mu) with mutations in the catalytic sites of one or both decapping enzymes was constructed. In a cell line commonly used for poxvirus studies, BS-C-1 monkey cells, the replication ability of the double mutant was drastically reduced by 60,000 fold compared to either of the single mutants or the wild type, confirming our hypothesis. Nevertheless, replication of D9muD10mu was much less impaired in RK13 rabbit cells. This host range effect suggests that an important role of the decapping enzymes is to prevent expression of antiviral factors that are more potent in BS-C-1 cells than in RK13 cells.

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