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

Abstract
Summary 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°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°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°C, neither VW+ nor VW− bacteria showed a haemagglutinating activity. When the bacteria were grown in CFA broth, only two strains grown at 25°C did not agglutinate any of the erythrocytes tested. The VW+ and VW− bacteria of the remaining strains, grown either at 25°C or 37°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°C adhered to HEp-2 cells more efficiently than either the VW− derivatives or the VW+ bacteria grown at 25°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.