The immune efficacy of a Streptococcus agalactiae immersion vaccine for different sizes of young tilapia

Abstract In order to explore the immune efficacy of a Streptococcus agalactiae immersion vaccine for young tilapia, three sizes of tilapia were selected and immunized a single time with an S. agalactiae immersion vaccine. The results that showed the whole cell antigen was crushed into nanoparticles and positive signals of antigen uptake were found in different sizes of tilapia and were mainly distributed in the gill, oropharynx, kidney, liver, spleen, intestine, and fish skin. The relative peak expression values for IgM, IgT, CD8+, and C3 from 1 g tilapia were significantly higher than those in 0.1 g and 0.5 g groups (P