Klebsiella pneumoniae heat-stable enterotoxin was purified to apparent homogenicity by the same techniques used to purify Escherichia coli heat-stable enterotoxin. The two toxins had the same potency in the suckling mouse assay and showed immunological cross-reactivity in enzyme-linked immunosorbent assay, neutralization of secretory activity by specific hyperimmune antisera, and protection against active challenge in rats immunized with a vaccine containing synthetically produced E. coli heat-stable enterotoxin.
