The enigma of Yersinia enterocolitica biovar 1A.

Yersinia enterocolitica, an important food- and water-borne enteropathogen causes acute diarrhea, terminal ileitis, and mesenteric lymphadenitis. It is represented by six biovars (1A, 1B, 2-5). The biovar 1A strains are generally regarded as avirulent as they lack pYV plasmid and major chromosomal virulence genes. Despite this, some biovar 1A strains produce disease symptoms indistinguishable from that produced by known pathogenic biovars (1B, 2-5). Suggested prospective studies to understand pathogenic potential of biovar 1A should focus on role of insecticidal toxins, urease, protease, superoxide dismutase, and host responses. These studies should also take into account the clonal groups of biovar 1A.