| Abstract: | An antiserum (WA-SAA) that agglutinates specifically with mouse virulent but not avirulent strains of Yersinia enterocolitica was used to identify virulence-associated factors by Western blot techniques. Several outer membrane polypeptides were identified only in the virulent strains, which included serotypes O:8, O:3, O:9, O:4,32, O:5,27, and O:21. These included three, and possibly four, major outer membrane polypeptides. The prominent high-molecular-weight species was demonstrated by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot, whereas the others were only revealed by the Western blot technique. Expression of these polypeptides correlated with antiserum agglutination reaction and the presence of a 42- and/or 82-megadalton plasmid. These polypeptides were highly temperature dependent and only slightly affected by the inclusion of 10 mM Ca2+ in the growth medium. These polypeptides were produced during both the logarithmic and stationary phases of growth at 37 degrees C. We suggest that the production of these specific polypeptides and calcium dependency may be coded for by the plasmid(s) but are regulated by independent mechanisms. These polypeptides appear to be novel markers specific for virulent strains of Y. enterocolitica and may be important to the pathogenicity of this organism. |
