Fu Songzhe, Ni Ping, Yang Qian, Hu Huizhi, Wang Qingyao, Ye Shigen, Liu Ying
College of Marine Technology and Environment, Dalian Ocean University, Dalian, P.R. China.
Key Laboratory of Environment Controlled Aquaculture, Ministry of Education, Dalian, P.R. China.
Can J Microbiol. 2021 Mar;67(3):231-248. doi: 10.1139/cjm-2020-0079. Epub 2020 Sep 17.
is one of the major pathogens in aquaculture. To identify the key virulence factors affecting pathogenesis of towards fish, we conducted a field investigation for three representative fish farms infected with . Multilocus sequence typing (MLST) and whole-genome sequencing were conducted to delineate the phylogenetic relationship and genetic divergence of . A total of 25 strains were isolated from the diseased fish and groundwater and were subtyped into 12 sequence types by MLST. Five virulence genes, , , , , and , were variably presented in the sequenced strains. The virulence gene profiles strongly correlated with the distinct pathogenicity of strains, with a strain harboring all five genes exhibiting the highest virulence towards fish. Phenotype assay confirmed that reduced virulence correlated with decreased motility and biofilm formation ability. Additionally, three types of type VI secretion system, namely T6SS1, T6SS2, and T6SS3, were identified in strains, which can be classified into six, four, and 12 subtypes, respectively. In conclusion, the results indicated that the virulence level of is mainly determined by the above virulence genes, which may play vital roles in environmental adaptation for
是水产养殖中的主要病原体之一。为了确定影响其对鱼类致病机制的关键毒力因子，我们对三个感染该病原体的代表性养鱼场进行了实地调查。进行了多位点序列分型（MLST）和全基因组测序，以描绘其系统发育关系和遗传差异。从患病鱼类和地下水中总共分离出25株该病原体菌株，并通过MLST将其分为12个序列类型。在测序菌株中，五个毒力基因（具体基因名称未给出）呈现出不同的分布情况。毒力基因谱与该病原体菌株的不同致病性密切相关，携带所有五个基因的菌株对鱼类表现出最高的毒力。表型分析证实，毒力降低与运动性和生物膜形成能力下降相关。此外，在该病原体菌株中鉴定出三种VI型分泌系统，即T6SS1、T6SS2和T6SS3，它们分别可分为六个、四个和十二个亚型。总之，结果表明该病原体的毒力水平主要由上述毒力基因决定，这些基因可能在其环境适应性中发挥重要作用
