Epizootic ulcerative syndrome causes cutaneous dysbacteriosis in hybrid snakehead ().

Cutaneous microbiota play an important role in protecting fish against pathogens. infection causes epizootic ulcerative syndrome (EUS) in fish, and by perturbing the integrity of the cutaneous microbiota, increases the potential for infection by pathogenic bacteria. However, whether the composition of the cutaneous microbiota is altered in fish with EUS, and if so, which species are changed and how this might influence infected fish, is still largely unclear. Considering the importance of cutaneous microbiota in maintaining host health, we hypothesized that infection significantly enhances the presence of certain bacterial pathogens in the cutaneous microbiota and causes cutaneous dysbacteriosis. To test this hypothesis, we compared the cutaneous microbiota compositions of hybrid snakehead () with and without infection using Illumina Miseq sequencing of the 16S rRNA gene. Our results showed that the cutaneous microbiota of hybrid snakehead were significantly altered subsequent to EUS infection and that the numbers of potentially pathogenic bacteria classified into the genera , , and were significantly enhanced in the cutaneous microbiota of hybrid snakehead with EUS, whereas bacteria classified into the genera , , , , , , , , , , , and were significantly reduced. These results imply that treatment for EUS should not only take into consideration the control of reproduction but should also focus on regulating the cutaneous microbiota of infected fish.