Lack of uptake of Renibacterium salmoninarum by gill epithelia of rainbow trout

The role of rainbow trout (Oncorhynchus mykiss, Walbaum) gill cells in uptake of the salmonid pathogen Renibacterium salmoninarum was examined using in vitro, whole animal and isolated perfused head models. Uptake of the pathogen was observed only when dissected gill tissue was exposed to the live pathogen. In contrast, live cells of Yersinia ruckeri interacted with the gill epithelia in the isolated perfused head model, confirming the findings of previous studies with whole animal and in vitro systems. These results are discussed in relation to the role of gill tissue in bacterial kidney disease (BKD) pathogenesis and in antigen trapping.