Estructura de Investigación Multidisciplinar en Biotecnología y BioMedicina (ERI BioTecMed), Department of Microbiology and Ecology, University of Valencia, 46100 Valencia, Spain.
Institute of Basic Medical Sciences and Department of Microbiology and Immunology, National Cheng Kung University, Tainan 701, Taiwan, Republic of China.
Microbiol Spectr. 2015 Jun;3(3). doi: 10.1128/microbiolspec.VE-0005-2014.
Vibrio vulnificus biotype 2 is the etiological agent of warm-water vibriosis, a disease that affects eels and other teleosts, especially in fish farms. Biotype 2 is polyphyletic and probably emerged from aquatic bacteria by acquisition of a transferable virulence plasmid that encodes resistance to innate immunity of eels and other teleosts. Interestingly, biotype 2 comprises a zoonotic clonal complex designated as serovar E that has extended worldwide. One of the most interesting virulence factors produced by serovar E is RtxA13, a multifunctional protein that acts as a lethal factor for fish, an invasion factor for mice, and a survival factor outside the host. Two practically identical copies of rtxA13 are present in all biotype 2 strains regardless of the serovar, one in the virulence plasmid and the other in chromosome II. The plasmid also contains other genes involved in survival and growth in eel blood: vep07, a gene for an outer membrane (OM) lipoprotein involved in resistance to eel serum and vep20, a gene for an OM receptor specific for eel-transferrin and, probably, other related fish transferrins. All the three genes are highly conserved within biotype 2, which suggests that they are under a strong selective pressure. Interestingly, the three genes are related with transferable plasmids, which emphasizes the role of horizontal gene transfer in the evolution of V. vulnificus in nutrient-enriched aquatic environments, such as fish farms.
创伤弧菌生物型 2 是温水弧菌病的病原体，这种疾病会影响鳗鱼和其他硬骨鱼，特别是在鱼类养殖场。生物型 2 是多源的，可能是通过获得可转移的毒力质粒从水生细菌中出现的，该质粒编码对鳗鱼和其他硬骨鱼先天免疫的抗性。有趣的是，生物型 2 包括一个被指定为血清型 E 的人畜共患病克隆复合体，该复合体已经在全球范围内扩展。血清型 E 产生的最有趣的毒力因子之一是 RtxA13，这是一种多功能蛋白，对鱼类具有致死作用，对小鼠具有侵袭作用，在宿主外具有生存作用。所有生物型 2 菌株中都存在两个几乎相同的 rtxA13 副本，一个位于毒力质粒中，另一个位于染色体 II 中。质粒还包含其他与鳗鱼血液中生存和生长相关的基因：vep07，编码一种参与抵抗鳗鱼血清的外膜（OM）脂蛋白的基因和 vep20，编码一种 OM 受体，该受体特异性结合鳗鱼转铁蛋白，可能还有其他相关鱼类转铁蛋白。这三个基因在生物型 2 中高度保守，这表明它们受到强烈的选择压力。有趣的是，这三个基因与可转移质粒有关，这强调了水平基因转移在创伤弧菌在富含营养的水生环境（如鱼类养殖场）中的进化中的作用。
