Distribution of the lpt-O gene in S. flexneri strains detected by PCR.

1Reactivity with monoclonal antibody MASF IV-1 (Reagensia AB) and monovalent antisera IV (Denka Seiken). Numbers of S. flexneri strains with MASF IV-1 positive or IV+ phenotype were listed.2+ and −/+ indicate the presence of the functional and inactivated lpt-O gene, respectively. Number of strains carrying the lpt-O gene is indicated in parentheses.3Serotype 4 av strains (2002091, NCTC 8296 and G1668) were serologically different from typical serotype 4a strains in the MASF IV-1 reactivity.4Serotype Yv strains were serologically different from typical serotype Y strains in the MASF IV-1 and monovalent antisera IV reactivity.