title: Adjuvant Immune Enhancement of Subunit Vaccine Encoding pSCPI of Streptococcus iniae in Channel Catfish (Ictalurus punctatus).
abstract: Channel catfish (Ictalurus punctatus) is an important agricultural fish that has been plagued by Streptococcus iniae (S. iniae) infections in recent years, some of them severe. C5a peptidase is an important virulent factor of S. iniae. In this study, the subunit vaccine containing the truncated part of C5a peptidase (pSCPI) was mixed with aluminum hydroxide gel (AH), propolis adjuvant (PA), and Freund's Incomplete Adjuvant (FIA). The immunogenicity of the pSCPI was detected by Western-blot in vitro. The relative percent survival (RPS), lysozyme activity, antibody titers, and the expression of the related immune genes were monitored in vivo to evaluate the immune effects of the three different adjuvants. The results showed that pSCPI exerted moderate immune protection (RPS = 46.43%), whereas each of the three adjuvants improved the immune protection of pSCPI. The immunoprotection of pSCPI + AH, pSCPI + PA, and pSCPI + FIA was characterized by RPS values of 67.86%, 75.00% and, 85.71%, respectively. Further, each of the three different adjuvanted pSCPIs stimulated higher levels of lysozyme activity and antibody titers than the unadjuvanted pSCPI and/or PBS buffer. In addition, pSCPI + FIA and pSCPI + PA induced expression of the related immune genes under investigation, which was substantially higher than the levels stimulated by PBS. pSCPI + AH significantly stimulated the induction of MHC II β, CD4-L2, and IFN-γ, while it induced slightly higher production of TNF-α and even led to a decrease in the levels of IL-1β, MHC I α, and CD8 α. Therefore, we conclude that compared with the other two adjuvants, FIA combined with pSCPI is a more promising candidate adjuvant against S. iniae in channel catfish.
authors.affiliation: Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. jiangjiejj2013@126.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Department of Aquaculture, Rongchang Campus, Southwest University, Chongqing 402460, China. zhengzonglin@126.com.
authors.forename: Zonglin
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. kywangsicau@126.com.|Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. kywangsicau@126.com.
authors.forename: Kaiyu
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. wangjun1986616@gmail.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. heyang@sicau.edu.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. welsicau@126.com.
authors.forename: Erlong
authors.initials: E
authors.lastname: Wang
authors.affiliation: Department of Aquaculture, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. chendf_sicau@126.com.
authors.forename: Defang
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. ouyang.ping@live.cn.|Department of Aquaculture, Rongchang Campus, Southwest University, Chongqing 402460, China. ouyang.ping@live.cn.
authors.forename: Ping
authors.initials: P
authors.lastname: Ouyang
authors.affiliation: Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. gengyisicau@126.com.|Department of Aquaculture, Rongchang Campus, Southwest University, Chongqing 402460, China. gengyisicau@126.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Geng
authors.affiliation: Department of Aquaculture, Sichuan Agricultural University, Wenjiang District Huimin Road No. 211, Chengdu 611130, China. hxldyq@126.com.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Huang
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics* / Q000378:metabolism; D000276:Adjuvants, Immunologic; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D010450:Endopeptidases / Q000235:genetics* / Q000378:metabolism; D005393:Fish Diseases / Q000235:genetics / Q000401:mortality / Q000517:prevention & control*; D015870:Gene Expression; D007059:Ictaluridae / Q000276:immunology* / Q000382:microbiology*; D007109:Immunity / Q000235:genetics; D007114:Immunization; D009113:Muramidase / Q000378:metabolism; D013291:Streptococcus / Q000235:genetics* / Q000276:immunology*; D022223:Vaccines, Subunit / Q000235:genetics* / Q000276:immunology*
chemical_list: D018829:Adhesins, Bacterial; D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D022223:Vaccines, Subunit; D009113:Muramidase; D010450:Endopeptidases; C053088:C5a peptidase
keywords: Channel catfish; Streptococcus iniae; adjuvant; immune effect; pSCPI; subunit vaccine