Bacterial expression of a human monoclonal antibody that inhibits in vitro adherence of Entamoeba histolytica trophozoites.

Abstract

Despite the medical importance of Entamoeba histolytica , neither an effective vaccine nor chemoprophylaxis to prevent amebiasis has yet been developed. On the other hand, it has been reported that passive immunization with murine monoclonal antibodies to several E. histolytica antigens is effective in preventing amebic liver abscess formation in animal models (1,2). Therefore, if human antibodies with such specificity can be obtained, it is possible that mortality from amebiasis could be reduced by passive immunization. However, hybridoma technology has not been very successful for the production of human monoclonal antibodies. Recently, new technologies have been established to generate human monoclonal antibodies. We have developed a vector for the expression of Fab fragments in Escherichia coli (3). Four recombinant human monoclonal antibody Fab fragments specific for E. histolytica have been prepared from the peripheral blood of a patient with an amebic liver abscess (4). However, these Fab fragments did not react with the surface of trophozoites, and did not inhibit amebic adherence to human erythrocytes. We report here the successful production of a recombinant human monoclonal antibody that inhibits in vitro adherence of E. histolytica trophozoites.