title: As a genetic adjuvant, CTA improves the immunogenicity of DNA vaccines in an ADP-ribosyltransferase activity- and IL-6-dependent manner.
abstract: Cholera toxin (CT) and its subunits (A and B) have been intensively investigated as adjuvants for protein-based vaccines. Their underlying mechanisms vary with respect to the inoculation route used. By fusing the CTA gene to either the HIV-1-derived Tat-Rev-Vif-Integrase-Nef fusion gene or the OVA gene, our study showed that the fusion of CTA in these DNA vaccines had no cytotoxic effect in vitro and significantly improved both the quantity and quality of the elicited CD8(+) T cell responses. Further experiments identified that the fusion of CTA in these DNA vaccines augmented the secretion of IL-6 in a manner that was dependent on its ADP-ribosyltransferase activity, and protein kinase A (PKA) was found to be the major mediator of its downstream signaling. By site-directed mutagenesis of the ADP-ribosyltransferase catalytic center and in vivo RNAi, we demonstrated that the ADP-ribosyltransferase activity and the upregulation of IL-6 were required for the CTA gene-mediated adjuvant effect. These findings demonstrate that when fused to an immunogen gene, the CTA gene could serve as a potent genetic adjuvant, providing new insights into the mechanisms of CTA as an adjuvant.
authors.affiliation: Shanghai Public Health Clinical Center & Institutes of Biomedical Sciences, Key Laboratory of Medical Molecular Virology of Ministry of Education/Health, Shanghai Medical College, Fudan University, Shanghai 201508, China.
authors.forename: Yanmin
authors.initials: Y
authors.lastname: Wan
authors.affiliation: Shanghai Public Health Clinical Center & Institutes of Biomedical Sciences, Key Laboratory of Medical Molecular Virology of Ministry of Education/Health, Shanghai Medical College, Fudan University, Shanghai 201508, China.
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Ren
authors.affiliation: Shanghai Public Health Clinical Center & Institutes of Biomedical Sciences, Key Laboratory of Medical Molecular Virology of Ministry of Education/Health, Shanghai Medical College, Fudan University, Shanghai 201508, China.
authors.forename: Yanqin
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Shanghai Public Health Clinical Center & Institutes of Biomedical Sciences, Key Laboratory of Medical Molecular Virology of Ministry of Education/Health, Shanghai Medical College, Fudan University, Shanghai 201508, China; Institute of Biomedical Science, Fudan University, Shanghai 200032, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Shanghai Public Health Clinical Center & Institutes of Biomedical Sciences, Key Laboratory of Medical Molecular Virology of Ministry of Education/Health, Shanghai Medical College, Fudan University, Shanghai 201508, China.
authors.forename: Zhidong
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Shanghai Public Health Clinical Center & Institutes of Biomedical Sciences, Key Laboratory of Medical Molecular Virology of Ministry of Education/Health, Shanghai Medical College, Fudan University, Shanghai 201508, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Xie
authors.affiliation: Shanghai Public Health Clinical Center & Institutes of Biomedical Sciences, Key Laboratory of Medical Molecular Virology of Ministry of Education/Health, Shanghai Medical College, Fudan University, Shanghai 201508, China; Institute of Biomedical Science, Fudan University, Shanghai 200032, China. Electronic address: jianqingxu2008@gmail.com.
authors.forename: Jianqing
authors.initials: J
authors.lastname: Xu
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism*; D000276:Adjuvants, Immunologic / Q000235:genetics*; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002460:Cell Line; D002772:Cholera Toxin / Q000276:immunology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005260:Female; D053583:Interleukin-1beta / Q000276:immunology; D015850:Interleukin-6 / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D011993:Recombinant Fusion Proteins / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology; D019444:Vaccines, DNA / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D053583:Interleukin-1beta; D015850:Interleukin-6; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; D002772:Cholera Toxin; D036002:ADP Ribose Transferases; D017868:Cyclic AMP-Dependent Protein Kinases
keywords: Adjuvant; Cholera toxin A; DNA vaccine; IL-6; T cell immunity