title: Complement C5a acts as molecular adjuvant in fish by enhancing antibody response to soluble antigen.
abstract: C5a, the most potent anaphylatoxin generated during complement activation, has important pro-inflammatory actions and has also been shown to enhance antigen-specific antibody response in mammals, thereby acting as a molecular adjuvant. In rainbow trout, C5a has been shown to have a chemoattractant ability and its receptor has also been found on potential APCs. In this study, we tested the possible role of trout C5a as a molecular adjuvant. We demonstrated the presence of native C5a in trout serum using the antibody generated by recombinant trout C5a, and then we generated recombinant infectious hematopoietic necrosis virus glycoprotein (G), and a G-C5a fusion protein to test the adjuvant activity of trout C5a. Recombinant G-C5a displayed a potent chemoattractant activity in contrast to G alone, indicating that the C5a portion of the fusion protein was functional. Thereafter, G-C5a, partially emulsified in a small quantity of IFA, was injected into one group of trout, while the other group of trout was inoculated with the same dose of recombinant G. At four to sixteen weeks post-injection, the serum IgM antibody levels of the fish injected with recombinant G-C5a were obviously higher than those injected with G protein alone. Thus, these results suggest, for the first time, that C5a acts as molecular adjuvant in teleost fish by enhancing antibody response to a soluble antigen.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Wu
authors.affiliation: Clear Spring Foods, Inc., Research Division, Buhl, ID 83316, USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: LaPatra
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Biological Sciences, Lake Superior State University, Sault Ste Marie, MI 49783, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address: sunyer@vet.upenn.edu.
authors.forename: J Oriol
authors.initials: JO
authors.lastname: Sunyer
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address: yzhang@ihb.ac.cn.
authors.forename: Yong-An
authors.initials: YA
authors.lastname: Zhang
mesh_terms: D000276:Adjuvants, Immunologic / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000956:Antigens, Viral / Q000378:metabolism*; D015936:Complement C5a / Q000235:genetics* / Q000378:metabolism; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D029142:Infectious hematopoietic necrosis virus / Q000276:immunology*; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000956:Antigens, Viral; D029941:Fish Proteins; D011993:Recombinant Fusion Proteins; D015936:Complement C5a
keywords: C5a; Complement; IHNV; Molecular adjuvant; Rainbow trout