Lund Vera, Espelid Sigrun, Mikkelsen Helene
Fiskeriforskning, Norwegian Institute of Fisheries and Aquaculture Research, 9291 Tromsø, Norway.
Dis Aquat Organ. 2003 Aug 15;56(1):31-42. doi: 10.3354/dao056031.
Atypical Aeromonas salmonicida strains comprise a heterogeneous group in terms of molecular and phenotypic characteristics. They cause various conditions of ulcer diseases or atypical furunculosis and are being isolated in increasing number from various fish species and geographical areas. Several marine fish species susceptible to atypical A. salmonicida, including spotted wolffish Anarhichas minor O., are now being farmed and new vaccines may be needed. A commercial furunculosis vaccine for salmon is reported to protect wolffish poorly against experimental challenge with atypical A. salmonicida. The protective antigen(s) in furunculosis vaccines is still unclear, but in oil-adjuvanted vaccine for Atlantic salmon Salmo salar L., the surface A-layer was shown to be important for protection. In spotted wolffish, the efficacy of atypical furunculosis vaccines seems to vary with the atypical A. salmonicida strains used as bacterin in the vaccine. In the present study we investigated whether differences in the A-layer protein among atypical strains might be responsible for the observed variation in vaccine efficacy. Atypical A. salmonicida strains from 16 fish species in 11 countries were compared by genome polymorphism analysis using amplified fragment length polymorphism (AFLP) fingerprinting and by comparative sequencing of the vapA genes encoding the A-protein. The A-protein sequences appeared to be highly conserved except for a variable region between Residues 90 to 170. Surprisingly, the grouping of strains based on AFLP- or A-protein sequence similarities was consistent. In addition, serological differences in the A-protein among the strains were demonstrated by an A-protein-specific monoclonal antibody. Vaccines based on atypical A. salmonicida strains possessing genetically and serologically different A-layer proteins were shown to result in significantly different protection in spotted wolffish.
非典型杀鲑气单胞菌菌株在分子和表型特征方面构成了一个异质群体。它们会引发各种溃疡疾病或非典型疖疮病，并且从不同鱼类物种和地理区域分离出的数量越来越多。包括斑点狼鱼（Anarhichas minor O.）在内的几种易感染非典型杀鲑气单胞菌的海水鱼类目前正在养殖，可能需要新的疫苗。据报道，一种用于鲑鱼的商业疖疮病疫苗对狼鱼抵抗非典型杀鲑气单胞菌的实验性攻击保护效果不佳。疖疮病疫苗中的保护性抗原仍不清楚，但在大西洋鲑（Salmo salar L.）的油佐剂疫苗中，表面A层被证明对保护很重要。在斑点狼鱼中，非典型疖疮病疫苗的效力似乎因用作疫苗菌苗的非典型杀鲑气单胞菌菌株而异。在本研究中，我们调查了非典型菌株之间A层蛋白的差异是否可能是观察到的疫苗效力差异的原因。通过使用扩增片段长度多态性（AFLP）指纹图谱的基因组多态性分析以及对编码A蛋白的vapA基因进行比较测序，对来自11个国家16种鱼类的非典型杀鲑气单胞菌菌株进行了比较。除了90至170位残基之间的可变区域外，A蛋白序列似乎高度保守。令人惊讶的是，基于AFLP或A蛋白序列相似性对菌株进行的分组是一致的。此外，一种A蛋白特异性单克隆抗体证明了菌株之间A蛋白的血清学差异。基于具有遗传和血清学不同A层蛋白的非典型杀鲑气单胞菌菌株的疫苗在斑点狼鱼中显示出显著不同的保护效果。
