Efficiency of Vaccination with Streptococcus agalactiae bacterin on Streptococcosis Prevention in Nile Tilapia(Thai)

Abstract

This research focused on examination of the possibility of vaccination against streptococcosis in Nile tilapia both in laboratory and net cage conditions. For the laboratory test, injection was used as the route for vaccination. Comparison between intraperitoneal and intramuscular injection was performed using tilapia of 230.0 + 5.7 g BW. Vaccine was prepared from Streptococcus agalactiae strain KKU 44002 killed with 2% formalin. Concentration of the bacterin was 1x108 CFU/ml and injection dosage was 0.1 ml/100 g fish BW. The results revealed that vaccinated fish showed significantly higher antibody titer and relative percent survival, compared with the unvaccinated control group (P< 0.05). Among vaccinated fish, increase of antibody titer and relative percent survival of the fish vaccinated by intraperitoneal injection was significantly higher than that of the fish vaccinated by intramuscular injection (P<0.05). The field experiment was carried out at a real cage culture system in Chee River, Tapratai District, Mahasarakam. Average BW of the tested fish was 368.8 + 7.8 g. Two from 7 cages were vaccinated with 1x108 CFU/ml of formalin-killed bacterin at the dosage of 0.3 ml/fish by intraperitoneal injection. From the result, vaccinated fish obviously showed clearly higher accumulative percent survival than unvaccinated fish through the culture period