The application of Streptococcus iniae vaccine and egg yolk immunoblobulin (IgY) from hen pre-immunized with the same vaccine on cultured grouper (Epinephelus coioides)

• Main Author: 李舒萍
• Other Authors: Guo-Gau Lee
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/54444362853264333899

碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 100 === This study evaluated the effectiveness of oral and injected vaccines prepared from formalin-killed Streptococcus iniae cells, as well as the protective effect of Epinephelus coioides fed with egg yolk immunoglobulin (IgY) from hens pre-immunized with the same vaccine-supplemented diets against Strep. iniae infection. In this experiment, the median lethal concentration (LD50) of the bacterium strain LW2010, was 1.89×105 CFU/fish body weight. The symptoms of Streptococcal infection included pop eyes, cloudy eyes, darkening of body, and erratic swimming, resulting in death. In active immunization, formalin-killed bacterin combined with soybean oil adjuvant was intraperitoneally (i.p.) injected into the juveniles in the experimental groups and had a good protective effect. Four months after the immunization, the survival rate in the challenge test was 92 % (RPS 91%), and the serum antibody titer was higher in the experiemental groups than in the control. Also, formalin-killed bacterin coated with agar had the best effectiveness in the grouper in the oral vaccine experiment. Four weeks after the injection, the survival rate in the challenge test was 100 % (RPS 100%), and its serum antibody titer was significantly higher than the control group. In passive immunization, the experimental groups fed diets contained 2 % immunized IgY had a better protective effect compared to the groups fed with non-immunized IgY and the blank; the survival rate was 80 % (RPS 80%) after the challenge and decreased to 53.33% (RPS 53%) in the second week. The results indicated that feeding diets supplemented with immunized IgY to fish had a significant protective effect and did not cause any apparent stress on the cultured fish.