Abstract
Adhesive capacities of Yersinia strains to L-929 cells were compared in respect to the presence of virulence plasmid and the effects of temperature (25°C and 37°C) for bacterial cultivation and for adsorption with L-929 cells. Yersinia pseudotuberculosis IB carrying virulence plasmid adhered remarkably to L-929 cells when the organisms were cultivated at 37°C and adsorbed on L-929 cells at 37°C. Low degree of adherence was observed in the same organisms with three other combinations of cultivation- and adsorption-temperatures (37°C vs 25°C, 25°C vs 37°C and 25°C vs 25°C). Adhesive capacity to L-929 cells was low in Y. pseudotuberculosis IB mutant lacking virulence plasmid as compared with that in the parent strain. Y. pseudotuberculosis strains showed higher adhesive capacities than Y. enterocolitica strains. Furthermore, formalin-inactivated Y. pseudotuberculosis IB, both cultivated and adsorbed at 37°C, showed as high adhesive capacity as the live organism. The results suggested that the adhesive factor of Yersinia depended greatly on plasmid and was expressed more efficiently when the organisms were cultivated at 37°C and adsorbed with L-929 cells at 37°C.
