FIG. 1.

Model of cysteine proteinase expression during infection by E. histolytica and E. dispar. E. dispar expresses at least three cysteine proteinases (EdCP1, EdCP2, and EdCP3) but cannot invade. E. histolytica expresses at least five cysteine proteinases, ACP1, ACP2, ACP3, EhCP5, and EhCP112. Extracellular cysteine proteinases cleave sIgA, degrade the extracellular matrix, activate complement, and degrade IgG to circumvent the host immune response. Reprinted from reference 82a with permission of the publisher.