Comparative antigenic proteins and proteomics of pathogenic Yersinia enterocolitica bio-serotypes 1B/O: 8 and 2/O: 9 cultured at 25°C and 37°C.

Yersinia enterocolitica is a Gram-negative enteric pathogen responsible for a number of gastrointestinal disorders; the most pathogenic bio-serotype is 1B/O: 8. In this study, we compared the antigenicity of the outer membrane proteins and proteomics of the whole-cell proteins of a pathogenic bio-serotype 2/O: 9 isolated in China and a bio-serotype 1B/O: 8 strain isolated in Japan. Using two-dimensional gel electrophoresis, we showed that the outer membrane proteins A (OmpA), C (OmpC) and F (OmpF) were the major antigens for both strains, although proteins located on the bacterial cell membrane and enzymes involved in energy metabolism were also identified as antigenic. We compared the whole-cell proteins of the two strains cultured at 25°C and 37°C and found portions of the outer membrane proteins (OmpX, OmpF and OmpA) were downregulated when the bacteria were cultured at 37°C, whereas urease subunit gamma (UreA), urease subunit alpha (UreC) and urease accessory protein (UreE), which are involved in urease synthesis, were upregulated when the bacteria were grown at 37°C. These observations will lay a foundation to selection of diagnostic markers for pathogenic Yersinia enterocolitica, and maybe contribute to choose the vaccine targets.