Gag- and Nef-specific CD4+ T cells recognize and inhibit SIV replication in infected macrophages early after infection

Proc Natl Acad Sci U S A. 2009 Jun 16;106(24):9791-6. doi: 10.1073/pnas.0813106106. Epub 2009 May 28.

Abstract

The precise immunological role played by CD4(+) T cells in retroviral infections is poorly defined. Here, we describe a new function of these cells, the elimination of retrovirus-infected macrophages. After experimental CD8(+) cell depletion, elite controlling macaques with set-point viral loads < or = 500 viral RNA copies/mL mounted robust Gag- and Nef-specific CD4(+) T cell responses during reestablishment of control with > or = 54% of all virus-specific CD4(+) T cells targeting these 2 proteins. Ex vivo, these simian immunodeficiency virus (SIV)-specific CD4(+) T cells neither recognized nor suppressed viral replication in SIV-infected CD4(+) T cells. In contrast, they recognized SIV-infected macrophages as early as 2 h postinfection because of presentation of epitopes derived from virion-associated Gag and Nef proteins. Furthermore, virus-specific CD4(+) T cells displayed direct effector function and eliminated SIV-infected macrophages. These results suggest that retrovirus-specific CD4(+) T cells may contribute directly to elite control by inhibiting viral replication in macrophages.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / metabolism
  • Gene Products, gag / metabolism*
  • Gene Products, nef / metabolism*
  • Macaca mulatta
  • Macrophages / virology*
  • RNA, Viral / blood
  • Simian Acquired Immunodeficiency Syndrome / immunology*
  • Simian Acquired Immunodeficiency Syndrome / virology
  • Simian Immunodeficiency Virus / genetics
  • Simian Immunodeficiency Virus / isolation & purification
  • Simian Immunodeficiency Virus / physiology*
  • Viral Load
  • Virus Replication / immunology*

Substances

  • Gene Products, gag
  • Gene Products, nef
  • RNA, Viral