The Petri laboraty is interested in how the protozoan parasite Entamoeba histolytica invades the human intestine to cause amebic colitis and liver abscess. His lab is focusing on the amebic contact-dependent cytotoxicity that destroys the human immune cells responding to the site of infection. The contact event prior to host cell killing is mediated by an E. histolytica cell surface lectin. They have identified, cloned, and expressed this lectin, and demonstrated its potential as a vaccine. Currently they are concentrating on identifying domains of the lectin involved in adherence and cell killing, and the application of this information to vaccine design.