Defining the directionality and quality of influenza virus–specific CD8+ T cell cross-reactivity in individuals infected with hepatitis C virus
Victoria Kasprowicz, Scott M. Ward, Alison Turner, Alexandros Grammatikos, Brian E. Nolan, Lia Lewis-Ximenez, Charles Sharp, Jenny Woodruff, Vicki M. Fleming, Stuart Sims, Bruce D. Walker, Andrew K. Sewell, Georg M. Lauer, Paul Klenerman
Victoria Kasprowicz, Scott M. Ward, Alison Turner, Alexandros Grammatikos, Brian E. Nolan, Lia Lewis-Ximenez, Charles Sharp, Jenny Woodruff, Vicki M. Fleming, Stuart Sims, Bruce D. Walker, Andrew K. Sewell, Georg M. Lauer, Paul Klenerman
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Research Article Immunology

Defining the directionality and quality of influenza virus–specific CD8+ T cell cross-reactivity in individuals infected with hepatitis C virus

Abstract

Cross-reactivity of murine and recently human CD8+ T cells between different viral peptides, i.e., heterologous immunity, has been well characterized. However, the directionality and quality of these cross-reactions is critical in determining their biological importance. Herein we analyzed the response of human CD8+ T cells that recognize both a hepatitis C virus peptide (HCV-NS3) and a peptide derived from the influenza neuraminidase protein (Flu-NA). To detect the cross-reactive CD8+ T cells, we used peptide-MHC class I complexes (pMHCs) containing a new mutant form of MHC class I able to bind CD8 more strongly than normal MHC class I complexes. T cell responses against HCV-NS3 and Flu-NA peptide were undetectable in normal donors. In contrast, some responses against the Flu-NA peptide were identified in HCV+ donors who showed strong HCV-NS3–specific reactivity. The Flu-NA peptide was a weak agonist for CD8+ T cells in HCV+ individuals on the basis of novel pMHCs and functional assays. These data support the idea of cross-reactivity between the 2 peptides, but indicate that reactivity toward the Flu-NA peptide is highly CD8-dependent and occurs predominantly after priming during HCV infection. Our findings indicate the utility of the novel pMHCs in dissecting cross-reactivity and suggest that cross-reactivity between HCV and influenza is relatively weak. Further studies are needed to relate affinity and functionality of cross-reactive T cells.

Authors

Victoria Kasprowicz, Scott M. Ward, Alison Turner, Alexandros Grammatikos, Brian E. Nolan, Lia Lewis-Ximenez, Charles Sharp, Jenny Woodruff, Vicki M. Fleming, Stuart Sims, Bruce D. Walker, Andrew K. Sewell, Georg M. Lauer, Paul Klenerman

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Figure 6

Analysis of function and pMHC staining patterns of HCV lines using a variant peptide.

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Analysis of function and pMHC staining patterns of HCV lines using a var...
(A) A short-term cell line was generated from donor 1144, as in Figure 5, by restimulation with HCV-NS3 and then stained using 3 different pMHC constructs (CD8hi, normal, and CD8lo) refolded around the Flu-NA peptide (top), HCV-NS3 peptide genotype 1 variant (middle), or genotype 4 variant (lower). (B) ELISPOT assay results from a T cell line derived from donor 1144 after incubation with HCV-NS3 genotype 1 peptide, genotype 4 peptide, or Flu-NA peptide at the concentrations shown. As previously observed, little response was seen against the Flu-NA peptide, but an enhanced response with the genotype 4 variant was observed, consistent with the enhanced binding to the CD8lo construct. (C) pMHC staining of T cell lines from HCV+ donors specific for 2 separate epitopes. CD8hi, normal, and CD8lo pMHC constructs were refolded using HCV-NS3 as done previously and HCV A2-2594-2602 ALYDVVTKL derived from NS5b. Preserved staining of the HCV-NS5b line was observed using CD8lo pMHCs, and staining was not enhanced with the CD8hi construct, consistent with a population of largely high-affinity, CD8-independent T cells. These data indicate that the failure of the T cells specific to the HCV-NS3 genotype 1 epitope CINGSCWTV to bind CD8lo pMHCs (as also seen in Figure 6A) is not universal in HCV and that the response to Flu-NA, which is only clearly seen with the CD8hi construct, is atypical. We previously reported that the HCV-NS5b peptide has a 50% maximal stimulation concentration (SD50) 2 logs lower than that of the NS3 epitope (21). This is consistent with peptide titration ELISPOT data from these lines, as illustrated.