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Journal of Virology, October 2007, p. 11032-11045, Vol. 81, No. 20
0022-538X/07/$08.00+0     doi:10.1128/JVI.00734-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Fowlpox Virus Encodes a Bcl-2 Homologue That Protects Cells from Apoptotic Death through Interaction with the Proapoptotic Protein Bak

Logan Banadyga, Jenna Gerig, Tara Stewart, and Michele Barry^*

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

Received 4 April 2007/ Accepted 30 July 2007

Poxviruses are renowned for encoding numerous immunomodulatory proteins capable of undermining potent immune defenses. One effective barrier against infection is apoptosis, a process controlled at the mitochondria by pro- and antiapoptotic members of the highly conserved Bcl-2 family of proteins. Although poxviruses are known to encode an array of effective inhibitors of apoptosis, members of the Avipoxvirus genus, which includes fowlpox virus, encode proteins with Bcl-2 homology. Here, we show that FPV039, a fowlpox virus protein with limited Bcl-2 homology, inhibited apoptosis in response to a variety of cytotoxic stimuli, including virus infection itself. Similar to other antiapoptotic Bcl-2 proteins, FPV039 localized predominantly to the mitochondria in both human and chicken cells and protected human cells from tumor necrosis factor alpha-induced loss of the mitochondrial membrane potential. In addition, coimmunoprecipitation revealed that FPV039 interacted constitutively with the proapoptotic Bcl-2 protein, Bak, in both human and chicken cells. Concordantly, FPV039 also inhibited apoptosis induced by the transient overexpression of Bak. To confirm these results in the context of virus infection, we generated a recombinant vaccinia virus lacking F1L, the endogenous apoptotic inhibitor in vaccinia virus, and expressing FPV039. In the context of vaccinia virus infection, FPV039 retained the ability to localize to the mitochondria and interacted with Bak. Moreover, FPV039 prevented the activation of Bak and protected infected cells from apoptosis induced by staurosporine and virus infection. Together, our data indicate that FPV039 is a functional Bcl-2 homologue that inhibits apoptosis by neutralizing the proapoptotic Bcl-2 family member Bak.

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* Corresponding author. Mailing address: Department of Medical Microbiology and Immunology, University of Alberta, 621 HMRC, 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 8 August 2007.

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Journal of Virology, October 2007, p. 11032-11045, Vol. 81, No. 20
0022-538X/07/$08.00+0     doi:10.1128/JVI.00734-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

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