西伯利亚鲟源嗜水气单胞菌致病菌的分离及其全菌苗的免疫效果

Isolation of Pathogenic Bacteria Aeromonas hydrophila from Acipenser baerii and Immune Effect of Its whole Cell Vaccine

从患细菌性败血症的西伯利亚鲟(Acipenser baerii)的体内分离到一株致病菌株X1,其对西伯利亚鲟的半数致死浓度(LC50)为5.62×105cfu/ml,具有较强毒力;经ATB细菌鉴定仪生理生化鉴定和16S rDNA序列分析,菌株X1为嗜水气单胞菌(Aeromonas hydrophila);其系统发育分析表明,菌株X1与嗜水气单胞菌ATCC35654(登录号:X74676.1)的亲缘关系最近,其同源性为99%。用0.30%福尔马林灭活,将菌株X1制成灭活全菌苗,对西伯利亚鲟进行注射免疫。研究结果表明,嗜水气单胞菌X1全菌苗能够明显提高西伯利亚鲟的血清抗体水平及总蛋白、免疫球蛋白、溶菌酶含量,而且在嗜水气单胞菌X1全菌苗中加入弗氏不完全佐剂,有利于进一步增强西伯利亚鲟血清抗体水平及总蛋白、免疫球蛋白、溶菌酶含量。此外,嗜水气单胞菌X1全菌苗对西伯利亚鲟抗嗜水气单胞菌X1人工感染也具有较好的免疫保护作用,其对西伯利亚鲟的免疫保护率为50%,而且在嗜水气单胞菌X1全菌苗中加入弗氏不完全佐剂,嗜水气单胞菌X1全菌苗对西伯利亚鲟抗嗜水气单胞菌X1人工感染的免疫保护作用更好,其对西伯利亚鲟的免疫保护率为70%。因此,将嗜水气单胞菌X1全菌苗用于西伯利亚鲟细菌性败血症的防治具有广阔的发展前景。

A pathogenic strain X1 was isolated from Siberian Sturgeon （Acipenser baerii ） suffering with bacterial septieaemia. The median lethal concentration （LC50） of strain X1 was 5.62 × 10^5 cfu/ml to healthy Siberian Sturgeon, which showed that strain X1 had rather strong virulence. Strain X1 was identified as Aeromonas hydrophila by physiological and biological studies and 16S rDNA sequence analysis, which indicates that it had close relativity with A. hydrophila strain ATCC35654 （locus number：X74676.1 ）, with a high homology of 99% . Strain X1 was inactivated by 0.30 % formalin and its whole cell vaccine was made to immune Siberian Sturgeon with injection. The experiment results showed that whole cell vaccine of A. hydrophila strain X1 could obviously enhance the level of serum anti-A.hydrophila antibodies - and the total counts of immunoglobulin, total proteins, as well as lysozyme. In addition, whole cell vaccine effectively prevented Siberian Sturgeon from being infected by A. hydrophila. The relative survival percent of Siberian Sturgeon was 50%. Further, whole cell vaccine with FIA improved relative survival percent to 70%, showing more effective immunity effect. Therefore, there is a potential to apply whole cell bacteria A. hydrophila strain X1 to prevention and cure of Siberian Sturgeon suffering with bacterial septicaemia.