Impact of epitope escape on PD-1 expression and CD8 T-cell exhaustion during chronic infection

Joseph N. Blattman, E. John Wherry, Sang Jun Ha, Robbert G. Van Der Most, Rafi Ahmed

Research output: Contribution to journalArticle

100 Scopus citations

Abstract

During some persistent viral infections, virus-specific T-cell responses wane due to the antigen-specific deletion or functional inactivation (i.e., exhaustion) of responding CD8 T cells. T-cell exhaustion often correlates with high viral load and is associated with the expression of the inhibitory receptor PD-1. In other infections, functional T cells are observed despite high levels of pathogen persistence. The reasons for these different T-cell fates during chronic viral infections are not clear. Here, we tracked the fate of virus-specific CD8 T cells in lymphocytic choriomeningitis virus (LCMV)-infected mice during viral clearance, the persistence of wild-type virus, or the selection and persistence of a viral variant that abrogates the presentation of a single epitope. Viral clearance results in PD-1lo functional virus-specific CD8 T cells, while the persistence of wild-type LCMV results in high PD-1 levels and T-cell exhaustion. However, following the emergence of a GP35V→A variant virus that abrogates the presentation of the GP33 epitope, GP33-specific CD8 T cells remained functional, continued to show low levels of PD-1, and reexpressed CD127, a marker of memory T-cell differentiation. In the same animals and under identical environmental conditions, CD8 T cells recognizing nonmutated viral epitopes became physically deleted or were PD-1hi and nonfunctional. Thus, the upregulation of PD-1 and the functional inactivation of virus-specific T cells during chronic viral infection is dependent upon continued epitope recognition. These data suggest that optimal strategies for vaccination should induce high-magnitude broadly specific T-cell responses that prevent cytotoxic T-lymphocyte escape and highlight the need to evaluate the function of vaccine-induced T cells in the context of antigens presented during virus persistence.

Original languageEnglish (US)
Pages (from-to)4386-4394
Number of pages9
JournalJournal of virology
Volume83
Issue number9
DOIs
StatePublished - May 1 2009

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology

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