A rapid and safe procedure for preparing the murine toxins of the plague bacillus (Yersinia pestis).

The murine toxins A and B of Y. pestis were purified from a crude extract of the nonencapsulated strain M23NP of Y. pestis using HPLC gel filtration. Toxins A and B had molecular weights of 240,000 and 120,000, respectively. Both toxins had isoelectric points of 3.8. The mouse LD50 of toxin A was 2.5 micrograms, that of toxin B was 1.8 micrograms. Of the protein injected on the column, approximately 9% was toxin, including 2.9% toxin A and 6.1% toxin B. The crude M23NP extract was used periodically over 10 months to purify lots of the toxins. Each HPLC purification required about 30 min.