title: Frequency, Private Specificity, and Cross-Reactivity of Preexisting Hepatitis C Virus (HCV)-Specific CD8+ T Cells in HCV-Seronegative Individuals: Implications for Vaccine Responses.
abstract: T cell responses play a critical role in controlling or clearing viruses. Therefore, strategies to prevent or treat infections include boosting T cell responses. T cells specific for various pathogens have been reported in unexposed individuals and an influence of such cells on the response toward vaccines is conceivable. However, little is known about their frequency, repertoire, and impact on vaccination. We performed a detailed characterization of CD8(+) T cells specific to a hepatitis C virus (HCV) epitope (NS3-1073) in 121 HCV-seronegative individuals. We show that in vitro HCV NS3-1073-specific CD8(+) T cell responses were rather abundantly detectable in one-third of HCV-seronegative individuals irrespective of risk factors for HCV exposure. Ex vivo, these NS3-1073-specific CD8(+) T cells were found to be both naive and memory cells. Importantly, recognition of various peptides derived from unrelated viruses by NS3-1073-specific CD8(+) T cells showed a considerable degree of T cell cross-reactivity, suggesting that they might in part originate from previous heterologous infections. Finally, we further provide evidence that preexisting NS3-1073-specific CD8(+) T cells can impact the T cell response toward peptide vaccination. Healthy, vaccinated individuals who showed an in vitro response toward NS3-1073 already before vaccination displayed a more vigorous and earlier response toward the vaccine.
  
  
  OBJECTIVE
  Preventive and therapeutic vaccines are being developed for many viral infections and often aim on inducing T cell responses. Despite effective antiviral drugs against HCV, there is still a need for a preventive vaccine. However, the responses to vaccines can be highly variable among different individuals. Preexisting T cells in unexposed individuals could be one reason that helps to explain the variable T cell responses to vaccines. Based on our findings, we suggest that HCV CD8(+) T cells are abundant in HCV-seronegative individuals but that their repertoire is highly diverse due to the involvement of both naive precursors and cross-reactive memory cells of different specificities, which can influence the response to vaccines. The data may emphasize the need to personalize immune-based therapies based on the individual's T cell repertoire that is present before the immune intervention.
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany Hanover Biomedical Research School, Hanover, Germany.
authors.forename: Shihong
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany Hanover Biomedical Research School, Hanover, Germany.
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Bakshi
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany.
authors.forename: Pothakamuri Venkata
authors.initials: PV
authors.lastname: Suneetha
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany.
authors.forename: Paraskevi
authors.initials: P
authors.lastname: Fytili
authors.affiliation: Núcleo de Bioinformática do Laboratório de Imunogenética, Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Dinler A
authors.initials: DA
authors.lastname: Antunes
authors.affiliation: Núcleo de Bioinformática do Laboratório de Imunogenética, Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Gustavo F
authors.initials: GF
authors.lastname: Vieira
authors.affiliation: Department of Clinical Immunology and Rheumatology, Hanover Medical School, Hanover, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Jacobs
authors.affiliation: Intercell AG, Vienna, Austria.
authors.forename: Christoph S
authors.initials: CS
authors.lastname: Klade
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Manns
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany.
authors.forename: Anke R M
authors.initials: AR
authors.lastname: Kraft
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany.
authors.forename: Heiner
authors.initials: H
authors.lastname: Wedemeyer
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany.
authors.forename: Verena
authors.initials: V
authors.lastname: Schlaphoff
authors.affiliation: Department of Gastroenterology, Hepatology, and Endocrinology, Hanover Medical School, Hanover, Germany cornberg.markus@mh-hannover.de.
authors.forename: Markus
authors.initials: M
authors.lastname: Cornberg
mesh_terms: D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D015331:Cohort Studies; D003429:Cross Reactions; D016174:Hepacivirus / Q000276:immunology*; D006526:Hepatitis C / Q000276:immunology / Q000517:prevention & control*; D018937:Hepatitis C Antibodies / Q000276:immunology; D006801:Humans; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D018937:Hepatitis C Antibodies; D014765:Viral Vaccines