title: Distinct effects of human herpesvirus 6 and human herpesvirus 7 on surface molecule expression and function of CD4+ T cells.
abstract: This study was undertaken to investigate the effects of newly isolated T lymphotropic viruses, human herpesvirus (HHV)-6 and HHV-7, on CD4+ T cells. We first examined changes in surface molecule expression on CD4+ T cells after infection with HHV-6 or HHV-7 by flow cytometry. Among surface molecules examined, CD3 expression appeared to decline markedly after infection with HHV-6 variant A (strain U1102) but the decreased level of CD3 expression after infection with HHV-6 variant B (strain Z29) was slight. Impairment of surface CD3 expression on HHV-6 variant A-infected cells was also demonstrated by measuring intracellular free Ca2+ concentration in response to anti-CD3 mAb. In contrast, HHV-7 infection induced a marked loss of surface CD4 expression, but the decline of CD3 expression was slight. Cytotoxic activity of virus-specific CD4+ CTL clones decreased after infection with both HHV-6 variant A or HHV-7 but the degree of reduction of cytotoxicity by HHV-6 variant B was not significant. Addition of lectin restored the cytotoxicity of HHV-7-infected CTL but not that of HHV-6 variant A-infected CTL. Northern blot analysis and immunoprecipitation showed that infection with HHV-6 and HHV-7 did not affect the transcription and protein synthesis of CD3 and CD4. These findings suggest that both HHV-6 and HHV-7 may directly cause T cell immunodeficiency but that the mechanisms of CD4+ T cell dysfunction mediated by HHV-6 and HHV-7 are different.
authors.affiliation: First Department of Internal Medicine, Ehime University School of Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Furukawa
authors.forename: M
authors.initials: M
authors.lastname: Yasukawa
authors.forename: Y
authors.initials: Y
authors.lastname: Yakushijin
authors.forename: S
authors.initials: S
authors.lastname: Fujita
mesh_terms: D017252:CD3 Complex / Q000235:genetics / Q000378:metabolism; D015704:CD4 Antigens / Q000235:genetics / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002999:Clone Cells / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D006566:Herpesviridae Infections / Q000209:etiology / Q000276:immunology; D015654:Herpesvirus 6, Human / Q000276:immunology* / Q000472:pathogenicity; D016199:Herpesvirus 7, Human / Q000276:immunology* / Q000472:pathogenicity; D006801:Humans; D007108:Immune Tolerance; D007153:Immunologic Deficiency Syndromes / Q000209:etiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology
chemical_list: D017252:CD3 Complex; D015704:CD4 Antigens; D012333:RNA, Messenger