The prevalence of the fish pathogen <Emphasis Type="Italic">Yersinia ruckeri</Emphasis> among representatives of the marine flora and fauna of the Sea of Okhotsk

This study investigates the spreading of the Gram-negative bacterium Yersinia ruckeri, pathogenic for fish, among representatives of the marine flora and fauna of the Sea of Okhotsk. The enzyme-linked immunosorbent assay (ELISA) revealed the presence of Y. ruckeri outer membrane antigens in 9 of the 29 samples obtained by washing the internal organs of fish, shellfish, crustaceans, and surfaces of algal thalli. Using lipopolysaccharide (LPS) containing a fluorescent label we detected LPS-binding proteins, which are a component of the innate immune system of invertebrates, in half of the samples studied. However, the simultaneous presence of Y. ruckeri and LPS-binding proteins was found only in brachiopods, scallops, and shrimps. It is assumed that this may be indicative of a particular response of the immune system of these animals to infection and/or manifestation of a toxic effect of Y. ruckeri.