The chemotactic response of Vibrio anguillarum to fish intestinal mucus ismediated by a combination of multiple mucus components

Chemotactic motility has previously been shown to be essential for the viru lence of Vibrio anguillarum in waterborne infections of fish. To investigat e the mechanisms by,which chemotaxis may function during infection, mucus w as isolated from the intestinal and skin epithelial surfaces of rainbow tro ut. Chemotaxis assays revealed that V. anguillarum swims towards both types of mucus, with a higher chemotactic response being observed for intestinal mucus. Work was performed to examine the basis, in terms of mucus composit ion, of this chemotactic response. Intestinal mucus was analyzed by using c hromatographic and mass spectrometric techniques, and the compounds identif ied were tested in a chemotaxis assay to determine the attractants present. A number of mucus-associated components, in particular, amino acids and ca rbohydrates, acted as chemoattractants for V. anguillarum. Importantly, onl y upon combination of these attractants into a single mixture were levels o f chemotactic activity similar to those of intestinal mucus generated. A co mparative analysis of skin mucus revealed its free amino acid and carbohydr ate content to be considerably lower than that of the more chemotactically active intestinal mucus. To study whether host specificity exists in relati on to vibrio chemotaxis towards mucus, comparisons with a human Vibrio path ogen were made, A. cheR mutant of a Vibrio cholerae El Tor strain was const ructed, and it was found that V. cholerae and V. anguillarum exhibit a chem otactic response to mucus from several animal sources in addition to that f rom the human jejunum and fish epithelium, respectively.