Vibrio anguillarum is the causative agent of vibriosis in many species important to aquaculture. We generated whole genome sequence (WGS) data on a diverse collection of 64 V. anguillarum strains, which we supplemented with 41 publicly available genomes to produce a combined dataset of 105 strains. These WGS data resolved six major lineages (L1-L6), and the additional use of multilocus sequence analysis (MLSA) clarified the association of L1 with serotype O1 and Salmonidae hosts (salmon/trout), and L2 with serotypes O2a/O2b/O2c and Gadidae hosts (cod). Our analysis also revealed a large-scale homologous replacement of 526-kb of core genome in an L2 strain from a con-specific donor. Although the strains affected by this recombination event are exclusively associated with Gadidae, we find no clear genetic evidence that it has played a causal role in host specialism. Whilst it is established that Vibrio species freely recombine, to our knowledge this is the first report of a contiguous recombinational replacement of this magnitude in any Vibrio genome. We also note a smaller accessory region of high single nucleotide polymorphism (SNP) density and gene content variation that contains lipopolysaccharide biosynthesis genes which may play a role in determining serotype.

鳗弧菌是许多对水产养殖重要的物种中弧菌病的病原体。我们在64个不同的集合上生成了全基因组序列（WGS）数据鳗弧菌菌株，我们补充了41个可公开获得的基因组，以产生105个菌株的组合数据集。这些WGS数据解析了六个主要谱系（L1-L6），另外使用了多基因座序列分析（MLSA）阐明了L1与血清型O1和鲑科 宿主（鲑鱼/鳟鱼）和血清型为O2a / O2b / O2c的L2和 d科主机（鳕鱼）。我们的分析还揭示了来自同种特异性供体的L2菌株中526kb核心基因组的大规模同源置换。尽管受此重组事件影响的菌株仅与d科，我们找不到明确的遗传证据证明它在宿主专业中起了因果作用。虽然已经确定弧菌 物种自由重组，据我们所知，这是任何规模的连续重组替换的首次报道 弧菌基因组。我们还注意到较高的单核苷酸多态性（SNP）密度和基因含量变异的较小附属区域，其中包含可能在确定血清型中起作用的脂多糖生物合成基因。