| Summary: | 碩士 === 國立屏東科技大學 === 動物疫苗科技研究所 === 97 === The phenotypic and genetic characterization of 92 isolated of fish pathogen Nocardia seriolae from sea water fish and fresh water fish, that were determined by pulse field gel electrophoresis (PFGE) and α-glucosidase activity by API ZYM kit. In PFGE analysis, digestions with restriction enzymes Xba I and Ase I produced 13 and 9 restriction pattern. In α-glucosidase activity, almost Taiwanese strains were positive, but 7 strains were no α-glucosidase activity. According to the result, 10 isolated strains were selected for anti-sera preparation and the formalin-killed bacteria were prepared. Largemouth bass were inoculated intraperitioneally with formalin-killed whole cell vaccine from 10 strains of N. seriolae and follow by secondary and third IP injection after primary immunization and secondary immunization. Increased nitro blue tetrazolium activity was observed in 2 strains at 14 weeks after third immunization. Increased lysozyme activity was observed in 3 strains at 14 weeks. The activity of specific immune response was monitored by an enzyme-linked immunosorbent assay and Western blot. The result indicated that antibodies of 2 strains N. seriolae WCA increased in largemouth bass at 14 weeks and they reacted with major whole cell sonicated antigen at 29 and 72 kDa. Finally, 961113 strain was selected to be vaccine candidate. In an attempt to develop a vaccine against N. seriolae, formalin-killed sonicated antigen, formalin-killed microfluidizer ( MF ) antigen, formalin-killed MF antigen mixed with Frednd’s Adjuvant Incomplete ( FIA ), formalin-killed MF antigen mixed with ISA 763A adjuvant, and formalin-killed MF antigen mixed with ISA 763A adjuvant and heat shock protein were injected into largemouth bass. In addition, fish were challenged with 961113 strain after immunized 4 weeks. The fish injected with MF antigen showed resistance against an artificial challenge with N. seriolae. These results suggest that protective immune responses against N. seriolae are induced in largemouth bass.
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