Genetic evidence that the outer membrane protein YOP1 ofYersinia enterocoliticamediates adherence and phagocytosis resistance to human epithelial cells

We studied the role of Yersinia enterocolitica outer membrane protein YOP1 in adherence and phagocytosis resistance to the human epithelial cell line, HEp-2. A 5.2-kb DNA fragment of the plasmid of Y. enterocolitica, serotype O : 9, which encodes a 225-kDa outer membrane protein (YOP1), was cloned into the mobilisable vector pRK290B. After introduction of the recombinant plasmid into a non-adherent Y. enterocolitica strain of serotype O : 5, the resulting transconjugant acquired adherence and phagocytosis resistance properties to HEp-2 cells. Furthermore, the plasmidless Y. enterocolitica strain of serotype O : 9 which is rapidly phagocytosed by HEp-2 cells also became phagocytosis-resistant after receipt of the YOP1-encoding plasmid. These results indicate that YOP1 mediates cell adherence and phagocytosis resistance to HEp-2 cells.