Oral vaccination of tilapia against Streptococcus agalactiae using Bacillus subtilis spores expressing Sip. Issue 86 (March 2019)

• Record Type: Journal Article
• Authors: Yao, Yuan-Yuan; Chen, Dan-Dan; Cui, Zheng-Wei; Zhang, Xiang-Yang; Zhou, Yuan-Yuan; Guo, Xia; Li, Ai-Hua; Zhang, Yong-An
• Is Part Of: Fish & shellfish immunology. Issue 86(2019)
• Page Start: 999
• Page End: 1008
• Publication Date: 2019-03
• Subjects: Oreochromis niloticus -- Bacterial infection -- Vaccine -- Bacillus -- Surface display; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2018.12.060
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: Streptococcus agalactiae infections are becoming an increasing problem in aquaculture because of significant morbidity and mortality, which restricts the healthy development of tilapia aquaculture. To seek safe and effective prevention measures, a Bacillus subtilis GC5 surface displayed vaccine was prepared and applied orally in tilapia. The study first showed that recombinant spores can engraft in the tilapia intestine. Then, the effect of protection and the immune responses were evaluated. The results of ELISA showed that Sip-specific antibody in the sera of GC5-Sip-immunized fish can be detected after the first oral administration when compared to the phosphate buffer saline (PBS) control group, and the levels of specific IgM gradually strengthened with boosting, so does the specific antibody against bacteria, proving that humoral immunity was induced. Quantitative real-time PCR (qRT-PCR) results showed that the immune-related gene expression of the gut and spleen exhibited a different rising trend in the GC5-Sip group, revealing that innate immune response and local as well as systemic cellular immunity were induced. The outcome of fish immunized with GC5-Sip spores provided a relative percent survival (RPS) of 41.7% against S. agalactiae and GC5 group had an RPS of 24.2%, indicating that GC5-Sip was safe and effective in protecting tilapia against bacterial infection. Our study demonstrated that the oral administration of B. subtilis spores expressing Sip could cause an effective immune response and offer good resistance to bacterial infection. Our work may lead to the development of new ideas for immunoprophylaxis against S. agalactiae infection. Highlights: Oral vaccine GC5-Sip spores for tilapia can resist S. agalactiae infection. GC5-Sip spores can engraft in the tilapia intestine. GC5-Sip spores can activate innate immune response. GC5-Sip spores can trigger humoral immunity in tilapia. GC5-Sip spores can induce local and systemic cellular immunity in tilapia.