Identification of Yersinia enterocolitica O15 lipopolysaccharide as a rough antigen

Lipopolysaccharide (LPS) of a reference strain of Yersinia enterocolitica serovar O15, Ye614, was examined for its chemical structure and antigenicity. The O15 LPS was partially hydrolyzed with diluted acetic acid and fractionated on a Sephadex G-50 column. Only one peak was detected at fractions where the R-core oligosaccharide of a Y. enterocolitica rough strain was eluted. The chemical compositions of this oligosaccharide and the O15 LPS were similar to those of the R-core oligosaccharide and the rough LPS, respectively. The O15 LPS was antigenically identical to the rough LPS in immunodiffusion tests. These results indicate that the O15 LPS of Y. enterocolitica is rough LPS and that antigenic factor O15 is a rough antigen.