A Chromosomal Locus Which Controls the Ability of Shigella flexneri to Evoke Keratoconjunctivitis.

The primary step in the pathogenesis of bacillary dysentery is the penetration of intestinal epithelial cells by shigellae. Lacking this capacity, Shigella flexneri becomes avirulent. By means of intergeneric conjugation between various Escherichia coli K-12 Hfr strains and S. flexneri 2a virulent recipients and by reciprocal transduction analysis with phage P1 vir, we established a locus on the genome of S. flexneri 2a which is necessary for the ability of this strain to penetrate epithelial cells as measured by the Sereney test for keratoconjunctivitis. This locus, termed kcpA (in reference to its involvement in provoking keratoconjunctivitis), has been positioned between the lac and gal chromosomal markers and is contransducible with the purE allele.