Effects of heat shock protein inducer on Hsp70 gene expression and immune parameters during Streptococcus iniae infection in a Persian sturgeon fry

Heat shock proteins (HSPs) as stress-related factors play a fundamental role in innate and adaptive immune responses in fish, which can be considered as strong candidates for the development of new methods for fish disease prevention. It has been proven that Pro-Tex® as a heat shock protein inducer (HSPi) reduces harmful effects of cellular stress by increasing the Hsp70 protein production. We evaluated the effects of Pro-Tex® as an HSPi in a Persian sturgeon, (Acipenser persicus) exposed to a pathogenic bacterium. Therefore, A. persicus fries were pre-treated with 25.00, 50.00 and 100 mg L-1 of Pro-Tex® and then, injected with Streptococcus iniae ATCC29178. The Hsp70 gene expressions were determined in various organs including liver, gill and intestine and lysozyme (LYZ) activities along with supplemental levels of complement component 3 (C3) and immunoglobulin M (IgM) were also determined in sturgeon blood in days 3 and 7 after infection. Expression of Hsp70 gene was increased during the first three days of infection and then, it was found to be down-regulated during the infection process. Also, levels of LYZ activity, C3 and IgM increased in a concentration-dependent manner; but these parameters decreased after 7 days. Our data suggest that induction of Hsp70 is a promising approach in modulation of immune response in A. persicus and it might be employed to confer protection in fish against bacterial infections.