[Enteropathogenic yersinias: pathogenicity factors and new diagnostic methods].

A limited number of serotypes of Yersinia enterocolitica and Y. pseudotuberculosis is enteropathogenic for humans. During the last decade molecular biology contributed significantly to the understanding of the pathogenicity of these enteric agents. All human pathogenic Yersiniae harbour a 70-kilobase plasmid which is essential for virulence expression. Presently, thirteen plasmid-encoded polypeptides have been identified. Two of them have been identified as true outer membrane proteins and at least ten are secreted into the culture medium. Plasmid-mediated pathogenic functions are survival in serum, resistance to phagocytosis, cell adhesion, and cytotoxicity. As chromosomal determinants two invasions, one heat-stable enterotoxin and one iron-utilization system have been identified. The contribution of the iron-uptake system to mouse lethality has been clearly demonstrated. The plasmid-encoded proteins have been turned out to be more suitable antigens for serologic diagnosis of yersiniosis (immunoblotting and indirect immunofluorescence) than whole bacterial antigens.