Lack of correlation between haemagglutination and adherence to epithelial cells in Yersinia pseudotuberculosis.

Yersinia pseudotuberculosis was examined for its haemagglutinating activity and adherence to cultured epithelial cells (HEp-2) in relation to possession of a virulence (VW) plasmid and to growth conditions. VW-lacking (VW-) bacteria were isolated from ten VW+ strains of each serovar which, after they were grown on CFA plates at 37 degrees C, agglutinated the erythrocytes from five different species. In contrast to the bacteria possessing the plasmid (VW+) half of the VW- bacteria, grown on CFA plates at 37 degrees C, did not agglutinate any of the erythrocytes used and the other half agglutinated only human erythrocytes. Furthermore, when grown on CFA plates at 25 degrees C, neither VW+ nor VW- bacteria showed a haemagglutinating activity. When the bacteria were grown in CFA broth, only two strains grown at 25 degrees C did not agglutinate any of the erythrocytes tested. The VW+ and VW- bacteria of the remaining strains, grown either at 25 degrees C or 37 degrees C, showed relatively high haemagglutinating activity. Adherence to HEp-2 cells did not correlate with haemagglutinating activity in Y. pseudotuberculosis; the VW+ bacteria grown at 37 degrees C adhered to HEp-2 cells more efficiently than either the VW- derivatives or the VW+ bacteria grown at 25 degrees C, regardless of the growth medium. These results indicate that some of the haemagglutinins detected on Y. pseudotuberculosis are not involved in the adherence to HEp-2 cells.