ADHERENCE AND INVASIVE CAPACITIES OF THE FISH PATHOGEN PASTEURELLA-PISCICIDA

Pasteurella piscicida strains were weakly or moderately adherent to ce ll lines, the levels of attachment being variable depending on the cel ls employed. All the isolates exhibited the highest binding capacity t o CHSE-214 cells. Adhesive capacities were affected by heat and sugars but not by proteinase K or by treatment with antisera raised against the lipopolysaccharides of P. piscicida, implicating components of gly coprotein(s) as ligands in the adhesion process. The isolates showed a great binding capacity to intestines from the marine fish hosts gilth ead sea bl ram, sea bass and turbot, with values ranging from 10(4) to 10(5) bacteria/g. Although the. piscicida strains showed a weak invas iveness in the poikilothermic cell lines employed as in vitro model, t he bacteria remained viable inside the infected cells at least for 2 d ays. The invasion process was inhibited by cytochalasin D indicating t he active participation of the host cell cytoskeleton in the internali zation of P. piscicida.