This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Teale, A. Articles by Barry, M. Search for Related Content PubMed PubMed Citation Articles by Teale, A. Articles by Barry, M.

 Previous Article  |  Next Article 

Journal of Virology, March 2009, p. 2099-2108, Vol. 83, No. 5
0022-538X/09/$08.00+0     doi:10.1128/JVI.01753-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Orthopoxviruses Require a Functional Ubiquitin-Proteasome System for Productive Replication

Alastair Teale, Stephanie Campbell, Nick Van Buuren, Wendy C. Magee, Kelly Watmough, Brianne Couturier, Robyn Shipclark, and Michele Barry^*

Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada T6G 2S2

Received 19 August 2008/ Accepted 11 December 2008

Cellular homeostasis depends on an intricate balance of protein expression and degradation. The ubiquitin-proteasome pathway plays a crucial role in specifically targeting proteins tagged with ubiquitin for destruction. This degradation can be effectively blocked by both chemically synthesized and natural proteasome inhibitors. Poxviruses encode a number of proteins that exploit the ubiquitin-proteasome system, including virally encoded ubiquitin molecules and ubiquitin ligases, as well as BTB/kelch proteins and F-box proteins, which interact with cellular ubiquitin ligases. Here we show that poxvirus infection was dramatically affected by a range of proteasome inhibitors, including MG132, MG115, lactacystin, and bortezomib (Velcade). Confocal microscopy demonstrated that infected cells treated with MG132 or bortezomib lacked viral replication factories within the cytoplasm. This was accompanied by the absence of late gene expression and DNA replication; however, early gene expression occurred unabated. Proteasomal inhibition with MG132 or bortezomib also had dramatic effects on viral titers, severely blocking viral replication and propagation. The effects of MG132 on poxvirus infection were reversible upon washout, resulting in the production of late genes and viral replication factories. Significantly, the addition of an ubiquitin-activating enzyme (E1) inhibitor had a similar affect on late and early protein expression. Together, our data suggests that a functional ubiquitin-proteasome system is required during poxvirus infection.

---

* Corresponding author. Mailing Address: Department of Medical Microbiology and Immunology, 621 HMRC, University of Alberta, Edmonton, Alberta, Canada T6G 2S2. Phone: (780) 492-0702. Fax: (780) 492-9828. E-mail: michele.barry{at}ualberta.ca

Published ahead of print on 24 December 2008.

These authors contributed equally.

---

Journal of Virology, March 2009, p. 2099-2108, Vol. 83, No. 5
0022-538X/09/$08.00+0     doi:10.1128/JVI.01753-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Basler, M., Lauer, C., Beck, U., Groettrup, M. (2009). The Proteasome Inhibitor Bortezomib Enhances the Susceptibility to Viral Infection. J. Immunol. 183: 6145-6150 [Abstract] [Full Text]  
• Sperling, K. M., Schwantes, A., Staib, C., Schnierle, B. S., Sutter, G. (2009). The Orthopoxvirus 68-Kilodalton Ankyrin-Like Protein Is Essential for DNA Replication and Complete Gene Expression of Modified Vaccinia Virus Ankara in Nonpermissive Human and Murine Cells. J. Virol. 83: 6029-6038 [Abstract] [Full Text]