Viral Bcl-2-mediated evasion of autophagy aids chronic infection of gammaherpesvirus 68

PLoS Pathog. 2009 Oct;5(10):e1000609. doi: 10.1371/journal.ppat.1000609. Epub 2009 Oct 9.

Abstract

Gamma-herpesviruses (gammaHVs) have developed an interaction with their hosts wherein they establish a life-long persistent infection and are associated with the onset of various malignancies. One critical virulence factor involved in the persistency of murine gamma-herpesvirus 68 (gammaHV68) is the viral homolog of the Bcl-2 protein (vBcl-2), which has been implicated to counteract both host apoptotic responses and autophagy pathway. However, the relative significance of the two activities of vBcl-2 in viral persistent infection has yet to be elucidated. Here, by characterizing a series of loss-of-function mutants of vBcl-2, we have distinguished the vBcl-2-mediated antagonism of autophagy from the vBcl-2-mediated inhibition of apoptosis in vitro and in vivo. A mutant gammaHV68 virus lacking the anti-autophagic activity of vBcl-2 demonstrates an impaired ability to maintain chronic infections in mice, whereas a mutant virus lacking the anti-apoptotic activity of vBcl-2 establishes chronic infections as efficiently as the wild-type virus but displays a compromised ability for ex vivo reactivation. Thus, the vBcl-2-mediated antagonism of host autophagy constitutes a novel mechanism by which gammaHVs confer persistent infections, further underscoring the importance of autophagy as a critical host determinant in the in vivo latency of gamma-herpesviruses.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Apoptosis Regulatory Proteins / genetics
  • Autophagy / genetics
  • Autophagy / immunology
  • Beclin-1
  • Gammaherpesvirinae / genetics*
  • Gammaherpesvirinae / immunology
  • Gammaherpesvirinae / physiology
  • Genes, Tumor Suppressor
  • Herpesviridae Infections / pathology
  • Lysosomes / virology
  • Mice
  • Mutation
  • Proto-Oncogene Proteins c-bcl-2 / genetics*
  • Rhadinovirus / genetics
  • Rhadinovirus / immunology
  • Rhadinovirus / physiology
  • Virulence

Substances

  • Apoptosis Regulatory Proteins
  • Beclin-1
  • Becn1 protein, mouse
  • Proto-Oncogene Proteins c-bcl-2