Enteropathogenic Escherichia call (EPEC) was found to exhibit a type III se
cretion-dependent, contact-mediated, hemolytic activity requiring the EspA,
EspB, and EspD secreted proteins. EspB and EspD display homology to pore-f
orming molecules. Our data suggest a mechanism to explain the requirement f
or an three Esp proteins in the transfer of EPEC proteins, such as Tir, int
o target cells.