Evidence for two genetic loci in Yersinia enterocolitica that can promote invasion of epithelial cells

Virulent strains of Yersinia enterocolitica cause disease syndromes ranging from mild gastroenteritis to lymphadenitis and septicemia. The ability of these bacteria to invade intestinal epithelial cells to gain access to the reticuloendothelial system is thought to be an important aspect of their virulence. We report here on the cloning of two Y. enterocolitica chromosomal loci, inv and ail, each of which confers an invasive phenotype on Escherichia coli HB101. The inv locus allows a uniformly high level of invasion in several tissue culture lines and is homologous to the inv gene of Yersinia pseudotuberculosis. The second locus, ail, shows more host specificity than inv in that it allows invasion to a variable degree of some cell lines (e.g., HEp-2, HEC1B, and CHO cells) but allows no invasion of others (e.g., Madin-Darby canine kidney cells).