ADHERENCE AND TOXICITY OF YERSINIA ENTEROCOLITICA 0:3 AND 0:9 CONTAINING VIRULENCE‐ASSOCIATED PLASMIDS FOR VARIOUS CULTURED CELLS

Abstract

Plasmid (47 and 44 megadaltons, respectively) containing strains of Y. enterocolitica O:3 and O:9 adhered to and were toxic for HEp-2 human epithelial carcinoma and Y-1 mouse adrenal tumor cells in vitro. At 37.degree. C, but not at room temperature, the adhesion of the bacteria led to rounding and partial detachment of the cultured cells. UV-inactivated plasmid-positive Y. enterocolitica were neither adherent nor toxic for the cells but readily endocytosed by HEp-2 cells. The adherence of plasmid-positive Y. enterocolitica O:3 and O:9 on epithelial cells may be pathogenentically important as an intitial step for intestinal colonization, and possibly in Y. enterocolitica-induced diarrhea. Plasmid-positive Y. enterocolitica also adhered to the surface of cultured human macrophages and were apparently not phagocytosed as effectively as the plasmid-negative derivatives of the same bacteria. Thus, resistance to phagocytosis may form an additional plasmid-dependent virulence property of Y. enterocolitica O:3 and O:9.