title: Persistent high frequencies of varicella-zoster virus ORF4 protein-specific CD4+ T cells after primary infection.
abstract: Open reading frame 4 (ORF4) of varicella-zoster virus (VZV) encodes an immediate-early protein that is believed to be important for viral infectivity and establishing latency. Evidence suggests that VZV-specific T cells are crucial in the control of viral replication, but there are no data addressing the existence of potential ORF4 protein-specific CD4+ T cells. We tested the hypothesis that VZV ORF4 protein-specific CD4+ T cells could be identified and characterized within the peripheral blood of healthy immune donors following primary infection. Gamma interferon (IFN-gamma) immunosorbent assays were used to screen peripheral blood mononuclear cells obtained from healthy seropositive donors for responses to overlapping ORF4 peptides, viral lysate, and live vaccine. High frequencies of ORF4 protein-specific T cells were detected ex vivo in individuals up to 52 years after primary infection. Several immunogenic regions of the ORF4 protein were identified, including a commonly recognized epitope which was restricted through HLA-DRB1*07. Total ORF4 protein-specific responses comprised 19.7% and 20.7% of the total lysate and vaccine responses, respectively, and were dominated by CD4+ T cells. Indeed, CD4+ T cells were found to dominate the overall virus-specific IFN-gamma cellular immune response both ex vivo and after expansion in vitro. In summary, we have identified an ORF4 protein as a novel target antigen for persistent VZV-specific CD4+ T cells, with implications for disease pathogenesis and future vaccine development.
authors.affiliation: MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom.
authors.forename: Louise
authors.initials: L
authors.lastname: Jones
authors.forename: Antony P
authors.initials: AP
authors.lastname: Black
authors.forename: Gathsaurie N
authors.initials: GN
authors.lastname: Malavige
authors.forename: Graham S
authors.initials: GS
authors.lastname: Ogg
mesh_terms: D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D002644:Chickenpox / Q000276:immunology / Q000378:metabolism; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D006684:HLA-DR Antigens / Q000276:immunology; D059811:HLA-DRB1 Chains; D014645:Herpesvirus 3, Human / Q000276:immunology* / Q000502:physiology; D022283:Herpesvirus Vaccines / Q000276:immunology; D006801:Humans; D017874:Immediate-Early Proteins / Q000276:immunology* / Q000378:metabolism; D007371:Interferon-gamma / Q000096:biosynthesis / Q000494:pharmacology; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D014764:Viral Proteins / Q000276:immunology* / Q000378:metabolism
chemical_list: D018985:Epitopes, B-Lymphocyte; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; C456920:HLA-DRB1*07 antigen; D022283:Herpesvirus Vaccines; D017874:Immediate-Early Proteins; C085824:ORF4 protein, Human herpesvirus 3; D010446:Peptide Fragments; D014764:Viral Proteins; D007371:Interferon-gamma