title: In Vivo Synthesis of Cyclic-di-GMP Using a Recombinant Adenovirus Preferentially Improves Adaptive Immune Responses against Extracellular Antigens.
abstract: There is a compelling need for more effective vaccine adjuvants to augment induction of Ag-specific adaptive immune responses. Recent reports suggested the bacterial second messenger bis-(3'-5')-cyclic-dimeric-guanosine monophosphate (c-di-GMP) acts as an innate immune system modulator. We recently incorporated a Vibrio cholerae diguanylate cyclase into an adenovirus vaccine, fostering production of c-di-GMP as well as proinflammatory responses in mice. In this study, we recombined a more potent diguanylate cyclase gene, VCA0848, into a nonreplicating adenovirus serotype 5 (AdVCA0848) that produces elevated amounts of c-di-GMP when expressed in mammalian cells in vivo. This novel platform further improved induction of type I IFN-β and activation of innate and adaptive immune cells early after administration into mice as compared with control vectors. Coadministration of the extracellular protein OVA and the AdVCA0848 adjuvant significantly improved OVA-specific T cell responses as detected by IFN-γ and IL-2 ELISPOT, while also improving OVA-specific humoral B cell adaptive responses. In addition, we found that coadministration of AdVCA0848 with another adenovirus serotype 5 vector expressing the HIV-1-derived Gag Ag or the Clostridium difficile-derived toxin B resulted in significant inhibitory effects on the induction of Gag and toxin B-specific adaptive immune responses. As a proof of principle, these data confirm that in vivo synthesis of c-di-GMP stimulates strong innate immune responses that correlate with enhanced adaptive immune responses to concomitantly administered extracellular Ag, which can be used as an adjuvant to heighten effective immune responses for protein-based vaccine platforms against microbial infections and cancers.
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824;
authors.forename: Fadel S
authors.initials: FS
authors.lastname: Alyaqoub
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824;
authors.forename: Yasser A
authors.initials: YA
authors.lastname: Aldhamen
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824; and.
authors.forename: Benjamin J
authors.identifier: http://orcid.org/0000-0001-7213-0953
authors.initials: BJ
authors.lastname: Koestler
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824; and.
authors.forename: Eric L
authors.identifier: http://orcid.org/0000-0002-6369-4180
authors.initials: EL
authors.lastname: Bruger
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824;
authors.forename: Sergey S
authors.initials: SS
authors.lastname: Seregin
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824;
authors.forename: Cristiane
authors.initials: C
authors.lastname: Pereira-Hicks
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824;
authors.forename: Sarah
authors.initials: S
authors.lastname: Godbehere
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824; and amalfit1@msu.edu watersc3@msu.edu.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Waters
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824; Department of Pediatrics, Michigan State University, East Lansing, MI 48824 amalfit1@msu.edu watersc3@msu.edu.
authors.forename: Andrea
authors.initials: A
authors.lastname: Amalfitano
mesh_terms: D056704:Adaptive Immunity / Q000276:immunology*; D000256:Adenoviridae / Q000276:immunology; D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000941:Antigens / Q000276:immunology*; D015153:Blotting, Western; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D058501:Enzyme-Linked Immunospot Assay; D005434:Flow Cytometry; D005822:Genetic Vectors; D007167:Immunotherapy / Q000379:methods*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D014161:Transduction, Genetic
chemical_list: D000276:Adjuvants, Immunologic; D000941:Antigens; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP