The Cytotoxic Enterotoxin of Aeromonas hydrophila Is Aerolysin

The channel-forming toxin aerolysin was identified 25 years ago by Bernheimer and Avigad (1), who gave the protein its name. Aerolysin was purified by Buckley et al. (2), and its structural gene, named aerA, was cloned and sequenced almost simultaneously by two groups (6, 7). Since then more than 50 articles describing the expression, secretion, and properties of aerolysin have appeared, and aerolysin has become one of the best-characterized bacterial channel-forming toxins. Virtually all of the available evidence indicates that aerolysin kills cells by forming discrete channels in their plasma membranes (for a recent review, see reference 8). Although it is certainly cytotoxic, it has not been shown to directly alter cyclic nucleotide levels and therefore does not satisfy the definition of an enterotoxin.