Motile Aeromonas Septicemia (MAS) disease caused by Aeromonas hydrophila infection has become a serious problem in the cultivation of catfish (Pangasius hypophthalmus). MAS control can be done by giving the vaccines. This study aimed to determine the proper and effective dose of bivalent vaccine for MAS control in catfish seeds.

A total of 10 isolates of A. hydrophila bacteria isolated from the kidney of catfish attacked by MAS disease were characterized, identified, and tested for their pathogenicity level through the Koch’s Postulate test. Two of ten isolates were selected as the most pathogenic isolates, namely CASO.O1.G and SBMI. 2. The experimental design used was a completely randomized design with five treatments and three replications, namely the bivalent vaccine with a dose of 109 cells/ml, 108 cells/ml, 107 cells/ml, 106 cells/ml, and control (PBS solution pH 7.0). Furthermore, the quantitative data were analyzed by using ANOVA, the Ducan Multiple Range Test for the real difference, and BNT. The parameters observed were antibody titer, survival rate, Relative Percent Survival (RPS), Mean Time to Death (MTD) or Mean Death Time (MDT), development of disease symptoms, and water quality.

The vaccine was heat-killed at 100 oC for 60 minutes. A total of 13 individuals catfish (9-13 cm total length) were kept in each aquarium (50x20x20 cm). A dose of 107 cells/ml (1,706.67) produced the highest antibody titer. The effectiveness of the vaccine can be seen from its RPS values (%) after vaccinated  with the dose of 108 cells/ml (100%), 106 cells/ml (100%), 109 cells/ml (97.22%), and 107 cells/ml (97.22%). The MDT value for control was one day, with a mortality rate of 97.43%. A similar result was found in the vaccine dose of 107 cell/ml; only one fish died was observed. Water quality parameters were in the tolerance range for the seed rearing period.

Keywords:Aeromonas hydrophila, bivalent vaccine, dose, Pangasius hypophthalmus