碩士 / 國立屏東科技大學 / 獸醫學系 / 93 / Streptococcosis was an important bacterial disease in cultured grey mullet ( Mugil cephalus L. ) and caused serious economic losses. From 1997 to 2004, fifty-one cases of diseased grey mullet with Gram-positive streptococcus-like organisms were collected from cultured farms in central Taiwan. Those cases were diagnosed by clinical pathological, histopathological, microbiological and molecular examinations. All diseased fish had congestion and hemorrhage on the body surface, and showed exophthalmia with or without conjunctival hemorrhage and corneal opacity. The main pathological changes were the presence of ascites, polyserositis and meningitis. The bacterial isolates obtained from the diseased fish, were Gram-positive streptococcus-like bacteria, catalase negative, oxidase negative but grew in 0-5％ NaCl broth. All the isolates grew over a wide temperature ranges ( 4-40℃). Expected 750bp PCR amplicons obtained by using a set of universal primers targeting for the 16S rDNA of Gram positive cocci from the isolates were determined and deposited in the GenBank. The results showed Lactococccus garvieae 90％ ( 45/51 ), Streptococcus agalactiae 5％ ( 3/51 ) and Streptococcus dysgalactiae 5％ ( 3/51 ), respectively. Epidemiologically, L. garvieae was a major bacterial pathogen in cultured grey mullet, occurred highly from May to September in Taiwan. Extracellular product profiles of L. garvieae of field strains, L. garvieae, S. agalactiae, S. dysgalactiae and S. iniae of standard strains were analyzed by protein electrophoresis. The results showed L. garvieae from field strains were similar to the standard strains and major molecular weight were about 56, 51 and 45.5 kDa, but they showed very different from S. agalactiae, S. dysgalactiae and S. iniae. The vaccines were prepared by using formalin- killed whole cells, whole cells adding extracellular products, and lysis of L. garvieae, and evaluated the efficacy in grey mullet. Fish were vaccinated single and booster by intraperitoneal ( i.p. ) injection with 107 and 109 colony-forming units ( CFU ) /fish, respectively. Fish immunized with single dose of whole cells 107 CFU were challenged by a dose of 106 and 108 CFU/fish and had a RPS ( relative percent survival; RPS ) of 67 and 0％, respectively. Fish with single and booster immunization with 109 CFU of the three trial vaccines, were respectively challenged with 106, 108 and 109 CFU/fish and had a RPS between 84-100％. IP immunization of both whole cells adding extracellular products and lysis showed two times of the RPS values higher than the whole cells group. In addition, the immunogenicity of the extracellular protein was identified by Western blots method.
| Identifer | oai:union.ndltd.org:TW/093NPUST541027 |
| Date | January 2005 |
| Creators | Jian-Lin Lee, 李建霖 |
| Contributors | Shinn-Shyong Tsai, 蔡信雄 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 63 |
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