杂色鲍肌肉萎缩症病原菌的分离鉴定及系统发育分析

Isolation,identification and phylogenetic analysis of pathogen from Haliotis diversicolor Reeve with withering syndrome

近几年中国南方杂色鲍(Haliotis diversicolorReeve)养殖场频繁爆发严重的肌肉萎缩症,该病能感染各种规格杂色鲍,死亡率很高。病鲍症状主要表现为外套膜和内脏团萎缩、无生气,附着力下降,最终死亡。该试验从病鲍组织分离到1株优势菌WS,人工感染试验证实其对健康杂色鲍有很强致病性,且与自然发病的杂色鲍症状相同。对菌株WS进行形态学观察和生理生化检测,结果显示与哈维氏弧菌(Vibrio harveyi)最为接近。为了进一步确定其分类地位,采用1对通用引物扩增其16S rDNA序列片断进行序列分析和同源性对比,构建系统发育树,结果表明,菌株WS与弧菌属的V.harveyi[AY750577]聚为1个分支,且同源性达99.70%。综合上述3种鉴定结果,确定该菌为哈维氏弧菌。

In recent years,there have often been serious withering syndrome in many breeding farms of Haliotis diversicolor Reeve in South China.It is infectious to all sizes of abalones with high mortality.The symptoms of sick abalones are：mantle and visceral mass shrink and become lethargic,weak in adhesion and finally die.A bacterial strain WS was isolated from the tissues of cultured H.diversicolor with withering syndrome.Artificial infection test proves that it has strong pathogenicity to healthy H.diversicolor and has symptoms similar to those which get sick spontaneously.We carried out a morphological observation and a test on the physiological and biochemical characteristics of strain WS,which indicates that it is most similar to Vibrio harveyi.In order to define its phylogenetic position,we sequenced,analyzed and compared the 16S rDNA genes whose partial fragments were amplified by a pair of universal primers,and finally constructed a molecular phylogenetic dendrogram based on the genetic distance.The result shows that strain WS and V.harveyi[AY750577] group into one cluster,with a 99.70% homology.According to morphological,physiological,biochemical and phylogenetic analyses,strain WS is proved to be V.harveyi.