title: West Nile virus-specific CD4 T cells exhibit direct antiviral cytokine secretion and cytotoxicity and are sufficient for antiviral protection.
abstract: CD4 T cells have been shown to be necessary for the prevention of encephalitis during West Nile virus (WNV) infection. However, the mechanisms used by Ag-specific CD4 T cells to protect mice from WNV encephalitis remain incompletely understood. Contrary to the belief that CD4 T cells are protective because they merely maintain the CD8 T cell response and improve Ab production, in this study we provide evidence for the direct antiviral activity of CD4 T cells that functions to protect the host from WNV encephalitis. In adoptive transfers, naive CD4 T cells protected a significant number of lethally infected RAG(-/-) mice, demonstrating the protective effect of CD4 T cells independent of B cells and CD8 T cells. To shed light on the mechanism of this protection, we defined the peptide specificities of the CD4 T cells responding to WNV infection in C57BL/6 (H-2(b)) mice, and used these peptides to characterize the in vivo function of antiviral CD4 T cells. WNV-specific CD4 T cells produced IFN-gamma and IL-2, but also showed potential for in vivo and ex vivo cytotoxicity. Furthermore, peptide vaccination using CD4 epitopes conferred protection against lethal WNV infection in immunocompetent mice. These results demonstrate the role of direct effector function of Ag-specific CD4 T cells in preventing severe WNV disease.
authors.affiliation: Department of Molecular Microbiology and Immunology, Oregon National Primate Research Center, Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, OR 97006, USA.
authors.forename: James D
authors.initials: JD
authors.lastname: Brien
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Uhrlaub
authors.forename: Janko
authors.initials: J
authors.lastname: Nikolich-Zugich
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000637:transplantation / Q000821:virology*; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism*; D003601:Cytotoxicity Tests, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000008:administration & dosage / Q000276:immunology*; D016056:Immunodominant Epitopes / Q000008:administration & dosage / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D019463:Mice, Inbred MRL lpr; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000276:immunology; D014901:West Nile Fever / Q000276:immunology* / Q000401:mortality / Q000517:prevention & control*; D053060:West Nile Virus Vaccines / Q000008:administration & dosage / Q000276:immunology; D014902:West Nile virus / Q000276:immunology*
chemical_list: D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D016056:Immunodominant Epitopes; D022223:Vaccines, Subunit; D053060:West Nile Virus Vaccines