Vaccine-induced antibody level as the parameter of the influence of environmental salinity on vaccine efficacy in Nile tilapia

Publication date: Available online 15 August 2018Source: Fish & Shellfish ImmunologyAuthor(s): Jing Wang, Run-Zhen He, Ge-Ling Lu, Heng-Li Luo, Dan-Qi Lu, An-Xing LiAbstractTo effectively increase production and improve economic returns, the co-culture of Nile tilapia (Oreochromis niloticus) and marine shrimp has been adopted in many countries, including China. Although O. niloticus is an euryhaline fish that can tolerate elevated salinities and even full-strength seawater, fluctuations in salinity levels can undoubtedly induce stress and affect the immune response of this fish. Therefore, this study assessed the impact of salinity on vaccine efficacy in Nile tilapia, which used serum antibody level as a surrogate marker to detect vaccine efficacy. Nile tilapia were acclimatized to 0, 10, 20, or 30 ppt salinity, and then immunized with a formalin-inactivated Streptococcus agalactiae vaccine. Significantly lower levels of antibody in vaccinated fish were found at 20 and 30 ppt salinity compared to 0 and 10 ppt salinity. White blood cell counts, absolute blood lymphocyte counts, and serum bactericidal activity levels were all significantly lower in vaccinated fish at 20 and 30 ppt salinity. Elevated cortisol levels were detected in all of the fish exposure to salinity. Concentrations of serum electrolytes (Na+ and Cl−) were significantly higher in fish at 30 ppt salinity, as compared to fish at lower salinities. Furthermore, the mRNA transcription levels of three of...
Source: Fish and Shellfish Immunology - Category: Biology Source Type: research