CHARACTERISTICS AND PATHOGENICITY OF NON-MELIBIOSE-FERMENTING STRAINSOF YERSINIA-PSEUDOTUBERCULOSIS O3

The biological properties of non-melibiose-fermenting (NMF) strains of Yersinia pseudotuberculosis O3 were investigated. These strains were clearly distinguished from representative melibiose-fermenting (MF) st rains of Y. pseudotuberculosis O3 by their pathogenicity in mice, sens itivity to some phages, production of catalase, restriction endonuclea se analysis of virulence plasmid DNA with BamHI, detection of specific yersinia outer-membrane proteins with SDS-PAGE, antigenicity of the o uter-membrane proteins and neutrophil resistance to phagocytosis, The pathogenicity of NMF strains was clearly less than that of MF strains. In addition, the resistance of NMF strains to phagocytosis and catala se activity was evidently weaker than that of MF strains. These result s suggested that the difference of pathogenicity was due to the abilit y of catalase production. Although the relationship between the above characteristics and melibiose-fermentation was not analysed, the patho genicity of Y. pseudotuberculosis O3 strains can probably be predicted by testing melibiose-fermentation and catalase production.