Genotypic Diversity and Population Structure of Vibrio vulnificus Strains Isolated in Taiwan and Korea as Determined by Multilocus Sequence Typing

The genetic diversity and population structure of Vibrio vulnificus isolates from Korea and Taiwan were investigated using PCR-based assays targeting putative virulence-related genes and multilocus sequence typing (MLST). BOX-PCR genomic fingerprinting identified 52 unique genotypes in 84 environmental and clinical V. vulnificus isolates. The majority (> 50%) of strains had pathogenic genotypes for all loci tested; moreover, many environmental strains had pathogenic genotypes. Although significant (p V. vulnificus strain and vice versa. MLST revealed 23–35 allelic types per locus analyzed, resulting in a total of 44 unique sequence types (STs). Two major monophyletic groups (lineages A and B) corresponding to the two known lineages of V. vulnificus were observed; lineage A had six STs that were exclusively environmental, whereas lineage B had STs from both environmental and clinical sources. Pathogenic and nonpathogenic genotypes predominated in MLST lineages B and A, respectively. In addition, V. vulnificus was shown to be in linkage disequilibrium (p V. vulnificus might be comprised of recently sub-divided lineages. These results suggested that the two lineages revealed by MLST correspond to two distinct ecotypes of V. vulnificus.

本研究采用靶向创伤弧菌（Vibrio vulnificus）推定毒力相关基因的PCR检测技术与多位点序列分型（multilocus sequence typing, MLST），对源自韩国及中国台湾地区的创伤弧菌分离株的遗传多样性与种群结构进行了探究。通过BOX-PCR基因组指纹图谱分析，研究人员在84株环境来源与临床来源的创伤弧菌分离株中鉴定出52种独特基因型。超过半数的供试菌株在所有检测位点上均携带致病相关基因型，且诸多环境菌株同样具备致病基因型。尽管存在显著关联（原文此处缺失统计学显著性标记），未发现分离来源与创伤弧菌菌株的主要系统发育谱系之间存在关联，反之亦然。多位点序列分型分析显示，每个被分析的位点存在23至35个等位基因类型，总计得到44种独特的序列型（sequence types, STs）。研究观察到对应于创伤弧菌两个已知进化谱系的两大单系群（谱系A与谱系B）：谱系A仅包含6种仅来自环境来源的序列型，而谱系B的序列型则同时涵盖环境与临床来源的分离株。致病与非致病基因型分别在MLST谱系B与谱系A中占主导地位。此外，研究证实创伤弧菌存在连锁不平衡（linkage disequilibrium）现象（原文此处缺失统计学显著性标记），提示创伤弧菌可能由新近分化的谱系构成。上述研究结果表明，多位点序列分型所揭示的两大谱系，对应于创伤弧菌的两种截然不同的生态型。