title: Th cell-independent immune responses to chimeric hemagglutinin/simian human immunodeficiency virus-like particles vaccine.
abstract: CD4(+) Th cells are believed to be essential for the induction of humoral and cellular immune responses. In this study we tested the effect and possible mechanisms of the major antigenic component in influenza, hemagglutinin (HA), in helping HIV Env to induce immune responses in CD4(+) T cell knockout (CD4 KO) mice. Simian HIV virus-like particles (SHIV VLPs) or phenotypically mixed chimeric influenza HA/SHIV VLPs were used as immunogens to immunize CD4 KO mice either i.p. or intranasally (i.n.). We found that chimeric HA/SHIV VLPs significantly induced a greater IgG Ab response in both i.p. and i.n. immunized mice and a greater IgA Ab response in mucosal washes in i.n. immunized mice compared with SHIV VLPs. Importantly, chimeric HA/SHIV VLPs induced approximately 3-fold higher neutralizing Ab titers against HIV 89.6 than SHIV VLPs in the absence of CD4(+) T cell help. There was also approximately 40% more specific lysis of the HIV Env-expressing target cells in chimeric HA/SHIV VLP-immunized than in SHIV VLP-immunized CD4 KO mouse splenocytes. Moreover, we have found that chimeric HA/SHIV VLPs could efficiently bind and activate dendritic cells and stimulate the activated dendritic cells to secret TNF-alpha and IFN-gamma. Therefore, chimeric HA/SHIV VLPs could efficiently prime and activate APCs, which could, in turn, induce immune responses in a CD4(+) T cell-independent manner. This study suggests a novel adjuvant role of influenza HA as well as a new strategy to develop more effective therapeutic vaccines for AIDS patients with low CD4(+) T cell counts.
authors.affiliation: Molecular Surgeon Research Center, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA. qizhiyao@bcm.tmc.edu
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Yao
authors.forename: Rongxin
authors.initials: R
authors.lastname: Zhang
authors.forename: Lizheng
authors.initials: L
authors.lastname: Guo
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Changyi
authors.initials: C
authors.lastname: Chen
mesh_terms: D000276:Adjuvants, Immunologic; D000281:Administration, Intranasal; D000818:Animals; D015704:CD4 Antigens / Q000502:physiology; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D015683:Gene Products, gag / Q000235:genetics / Q000276:immunology; D006678:HIV / Q000235:genetics / Q000276:immunology*; D015483:HIV Antibodies / Q000096:biosynthesis* / Q000276:immunology; D019302:HIV Envelope Protein gp160 / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology*; D006801:Humans; D007114:Immunization / Q000379:methods; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000276:immunology; D007274:Injections, Intraperitoneal; D007371:Interferon-gamma / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009500:Neutralization Tests; D016865:Reassortant Viruses / Q000276:immunology*; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014616:Vaccinia virus / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*; D014771:Virion / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D015704:CD4 Antigens; D015683:Gene Products, gag; D015483:HIV Antibodies; D019302:HIV Envelope Protein gp160; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007074:Immunoglobulin G; D014409:Tumor Necrosis Factor-alpha; D014765:Viral Vaccines; C483468:hemagglutinin, human influenza A virus; D007371:Interferon-gamma