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Genotypic and phenotypic characterization of Edwardsiella isolates from different fish species and geographical areas in Asia: Implications for vaccine development
- Saurabh Dubey, Biswajit Maiti, Sung‐Hyun Kim, Sangeetha Madambithara Sivadasan, Dhamotharan Kannimuthu, Pramod Kumar Pandey, Shivani Kallappa Girisha, Stephen Mutoloki, Shih‐Chu Chen, Øystein Evensen, Indrani Karunasagar, Hetron Mweemba Munang´andu
- Journal of fish diseases 2019 v.42 no.6 pp. 835-850
- Edwardsiella hoshinae, Edwardsiella ictaluri, Edwardsiella piscicida, Edwardsiella tarda, bacterial antigens, fish, fish diseases, genotyping, monophyly, phenotype, ribosomal RNA, vaccine development, vaccines, India, South Korea, Taiwan
- The genus Edwardsiella 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 E. tarda with phenotypic homology estimated at 85.71% based on API‐20E biochemical tests. Genotyping using 16S rRNA put all isolates together with E. anguillarum, E. hoshinae, E. tarda, E. piscicida and E. ictaluri reference strains in a monophyletic group. In contrast, the gyrB phylogenetic tree clearly separated E. ictaluri, E. tarda and E. hoshinae reference strains from our isolates and put our isolates into two groups with group I being homologous with the E. anguillarum reference strain while group II was homologous with the E. piscicida reference strain. Hence, our findings point to E. piscicida and E. anguillarum 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.