Efficacy study of Aeromonas hydrophila vaccine by immersion and oral administration in hybrid catfish
1998
Krongkaew Plaimast
Efficacy study of formalin-killed Aeromonas hydrophila vaccine was studied in hybrid catfish with average weight of 1.74 gm. Catfish were immersed in 1.5 percent saline solution for 2 minutes and vaccinated by immersion for an hour with optimum aeration. Then they were raised for three months with diet containing vaccine at different period at one, two, three and four weeks per month. After challenging with virulent A. hydrophila by intraperitoneal injection to determine the effectiveness of vaccine, all vaccinated fish had higher survival rate than the unvaccinated control after seven days of experimental infection (p0.01). Fish fed with diet containing vaccine for four, three, two and one week per month had survival rate of 75.00 +- 0.00 percent, 70.00 +- 0.00 percent, 68.33 +- 2.89 percent and 61.67 +- 2.89 percent respectively while control had 46.67 +- 2.89 percent. Similar result was found after comparison of Relative Percent Survival (RPS) in which the longer the fish were fed with diet containing vaccine the higher the RPS would be and the differences amongst these RPS values were highly significant (p0.01). However, all vaccinated and control fish did not show any significant difference of the antibody titer values after three months of the trial. It can be concluded from this study that initial immunization of hybrid catfish by hyperosmotic immersion followed by oral administration upto three months could enhance the specific immunity against A. hydrophila infection even though the fish did not develop significant amount of antibody in serum.
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