Determination of the heterogeneous interactome between Edwardsiella tarda and fish gills

Edwardsiellosis caused by Edwardsiella tarda is a frequent occurrence throughout the world and has resulted in extensive losses in aquaculture. However, information regarding to protein–protein interaction between the pathogenic cells and host is not available although the portal of entry of the pathogen is determined. In this study, fish gill and bacterial pull-down approaches were used to isolate both bacterial outer membrane proteins that bind to gills and fish gill proteins that interact with bacterial cells, respectively. Eight interacting bacterial proteins and twelve interacting fish proteins were obtained. The genes of seven bacterial proteins were cloned and expressed for preparation of antibodies. The prepared antibodies were used to investigate protein–protein interactions between bacterial cells and fish gills. Five heterogeneous protein–protein interactions were determined. Moreover, the protective ability of three of the bacterial recombinant proteins, selected at random, was investigated in a mouse model where they showed significant protection. The gill proteins were highly homologous proteins with from humans and other animals where they are known to be involved in host immunity. These findings indicate that the heterogeneous interactome has significantly biological significance. Our results demonstrate a way to determine and understand the heterogeneous interaction between of E. tarda and gills.

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► We used fish gill and bacterial cells as affinity beads.
► We obtained bacterial proteins that bind to gill cells, and fish gill proteins that interact with bacterial cells.
► Five of grill and bacterial heterogeneous protein–protein interaction were established.
► Three randomly selected bacterial proteins are protective immunogens.
► All fish gill proteins were highly homologous proteins with from humans where they are known to be involved in host immunity.