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Protective effect of human leukocyte antigen B27 in hepatitis C virus infection requires the presence of a genotype-specific immunodominant CD8+ T-cell epitope.

ABSTRACT:

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Human leukocyte antigen B27 (HLA-B27) is associated with protection in human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infection. This protective role is linked to single immunodominant HLA-B27-restricted CD8+ T-cell epitopes in both infections. In order to define the relative contribution of a specific HLA-B27-restricted epitope to the natural course of HCV infection, we compared the biological impact of the highly conserved HCV genotype 1 epitope, for which the protective role has been described, with the corresponding region in genotype 3 that differs in its sequence by three amino acid residues. The genotype 3a peptide was not recognized by CD8+ T cells specific for the genotype 1 peptide. Furthermore, patients with acute or chronic infection with HCV genotype 3a did not mount T-cell responses to this epitope region, and their autologous viral sequences showed no evidence of T-cell pressure. Finally, we found a significantly higher frequency of HLA-B27 positivity in patients with chronic HCV genotype 3a infection compared to genotype 1 infection, indicating that there is no protection by HLA-B27 in HCV genotype 3 infection.

Conclusion

Our data indicate that the protective effect of HLA-B27 is limited to HCV genotype 1 infection and does not expand to other genotypes such as genotype 3a. This can most likely be explained by intergenotype sequence diversity leading to the loss of the immunodominant HLA-B27 epitope in viral strains other than genotype 1. Our results underline the central role of a single HLA-B27-restricted epitope-specific CD8+ T-cell response in mediating protection in HCV genotype 1 infection.

SUBMITTER: Neumann-Haefelin C

PROVIDER: S-EPMC4396188 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature

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Protective effect of human leukocyte antigen B27 in hepatitis C virus infection requires the presence of a genotype-specific immunodominant CD8+ T-cell epitope.

Neumann-Haefelin Christoph C Timm Jörg J Schmidt Julia J Kersting Nadine N Fitzmaurice Karen K Oniangue-Ndza Cesar C Kemper Michael N MN Humphreys Isla I McKiernan Susan S Kelleher Dermot D Lohmann Volker V Bowness Paul P Huzly Daniela D Rosen Hugo R HR Kim Arthur Y AY Lauer Georg M GM Allen Todd M TM Barnes Eleanor E Roggendorf Michael M Blum Hubert E HE Thimme Robert R

Hepatology (Baltimore, Md.) 20100101 1

<h4>Unlabelled</h4>Human leukocyte antigen B27 (HLA-B27) is associated with protection in human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infection. This protective role is linked to single immunodominant HLA-B27-restricted CD8+ T-cell epitopes in both infections. In order to define the relative contribution of a specific HLA-B27-restricted epitope to the natural course of HCV infection, we compared the biological impact of the highly conserved HCV genotype 1 epitope, for which th ...[more]

PMID: 20034048

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Project description:Trypanosoma cruzi infection is controlled but not eliminated by host immunity. The T. cruzi trans-sialidase (TS) gene superfamily encodes immunodominant protective antigens, but expression of altered peptide ligands by different TS genes has been hypothesized to promote immunoevasion. We molecularly defined TS epitopes to determine their importance for protection versus parasite persistence. Peptide-pulsed dendritic cell vaccination experiments demonstrated that one pair of immunodominant CD4+ and CD8+ TS peptides alone can induce protective immunity (100% survival post-lethal parasite challenge). TS DNA vaccines have been shown by us (and others) to protect BALB/c mice against T. cruzi challenge. We generated a new TS vaccine in which the immunodominant TS CD8+ epitope MHC anchoring positions were mutated, rendering the mutant TS vaccine incapable of inducing immunity to the immunodominant CD8 epitope. Immunization of mice with wild type (WT) and mutant TS vaccines demonstrated that vaccines encoding enzymatically active protein and the immunodominant CD8+ T cell epitope enhance subdominant pathogen-specific CD8+ T cell responses. More specifically, CD8+ T cells from WT TS DNA vaccinated mice were responsive to 14 predicted CD8+ TS epitopes, while T cells from mutant TS DNA vaccinated mice were responsive to just one of these 14 predicted TS epitopes. Molecular and structural biology studies revealed that this novel costimulatory mechanism involves CD45 signaling triggered by enzymatically active TS. This enhancing effect on subdominant T cells negatively regulates protective immunity. Using peptide-pulsed DC vaccination experiments, we have shown that vaccines inducing both immunodominant and subdominant epitope responses were significantly less protective than vaccines inducing only immunodominant-specific responses. These results have important implications for T. cruzi vaccine development. Of broader significance, we demonstrate that increasing breadth of T cell epitope responses induced by vaccination is not always advantageous for host immunity.

Dataset Information

Protective effect of human leukocyte antigen B27 in hepatitis C virus infection requires the presence of a genotype-specific immunodominant CD8+ T-cell epitope.

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Conclusion

Publications

Protective effect of human leukocyte antigen B27 in hepatitis C virus infection requires the presence of a genotype-specific immunodominant CD8+ T-cell epitope.

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