Cytotoxin is thought to form hydrophilic pores in cell membranes. Produced as a cell-associated inactive precursor which is not secreted extracellularly. The toxin is converted into its active form by the action of proteases concomitantly with cell lysis and is released into the medium. This protein toxin may be one of the virulence factors because it shows strong cytotoxic effects on most eukaryotic cells, especially leukocytes. Belongs to the aerolysin family.