Quantitative differentiation of Yersinia pestis strains by their murine toxin and fraction I contents.

Until now the serological typing of Yersinia pestis into subgroups has not proved possible because all the antigenic components are present in each isolate. Using acrylamide disk electrophoresis it was observed that differences exist in the protein distribution patterns of aqueous extracts from various Y. pestis isolates. One component that was especially plentiful in some Javanese and South American isolates was identified as the murine toxin. The amount of murine toxin varies significantly from isolate to isolate, and so permits them to be roughly grouped. In 28 degrees C cultures the variation in the murine toxin content is independent of the variation in the F-I content. A new method of typing based on this 2-trait variation in quantities, in contrast to classical typing based on qualitative differences, might prove to be a means of differentiating Y. pestis isolates.