Evaluation of a live attenuated vaccine against Edwardsiella piscicida by 16S rRNA sequencing

A complex and dynamic community of microorganisms is attached to the mucosal surface of the fish gut. Gut microbes play important roles in fish metabolism and immunity. Edwardsiella piscicida infection of turbot causes Edwardsiellosis, and vaccination is an effective method to prevent and control aquaculture diseases. Here, intraperitoneal vaccination by E. piscicida 10Δ, a live attenuated vaccine candidate, significantly upregulated the expression of immune response-related genes in the turbot spleen and enhanced the serum antibody titers of IgM. 16S rRNA amplicon sequencing revealed that the vaccination of E. piscicida 10Δ slightly reduced the relative abundance of intestinal microbiota in turbot. Meanwhile, E. piscicida 10Δ potentially conferred the intestinal microbiota metabolic capacity associated with carbohydrate metabolism, while hypothetically impaired their metabolic capacity related to fatty acid degradation and amino acid metabolism. Collectively, E. piscicida 10Δ can effectively stimulate the host immune responses and has no apparent influence on the relative abundance of intestinal microbiota, which can thus be considered as a potentially safe live attenuated vaccine.