Genotypic and phenotypic characterization of <i>Edwardsiella</i> isolates from different fish species and geographical areas in Asia: Implications for vaccine development

다국어 초록 (Multilingual Abstract)

<P> The genus <I>Edwardsiella</I> is one of the major causes of fish diseases globally. Herein, we examined 37 isolates from ten different fish species from India, South Korea and Taiwan to gain insight into their phenotypic and genotypic properties, of which 30 were characterized as <I>E. tarda</I> with phenotypic homology estimated at 85.71% based on API-20E biochemical tests. Genotyping using 16S rRNA put all isolates together with <I>E. anguillarum, E. hoshinae, E. tarda, E. piscicida and E. ictaluri</I> reference strains in a monophyletic group. In contrast, the gyrB phylogenetic tree clearly separated <I>E. ictaluri, E. tarda and E. hoshinae</I> reference strains from our isolates and put our isolates into two groups with group I being homologous with the <I>E. anguillarum</I> reference strain while group II was homologous with the <I>E. piscicida</I> reference strain. Hence, our findings point to <I>E. piscicida</I> and <I>E. anguillarum</I> as species infecting different fish species in Asia. Homology of the ompW protein suggested that strains with broad protective coverage could be identified as vaccine candidates. This study underscores the importance of combining genotyping with phenotyping for valid species classification. In addition, it accentuates the importance of phylogenetic comparison of bacterial antigens for identification of potential vaccine candidates. </P>