ABSTRACT
Among the 11 species included in the genus Yersinia, three are pathogenic for humans and other animals: Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica (except biotype 1A). All pathogenic species harbor a conserved 70 kb plasmid designated pYV (for plasmid associated with Yersinia virulence) which is essential for their virulence phenotype (see chapter 16 for more details about this plasmid). Pathogenic Yersinia can be further subdivided into low-pathogenicity strains, i.e. strains that induce a mild intestinal infection in humans and are non-lethal for mice at low doses, and highpathogenicity strains which cause severe systemic infections in humans and are mouselethal at low doses.
