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093 GAL-LECTIN MUCOSAL VACCINE WITH CPG-ODN ADJUVANT CONFERS PROTECTIVE IMMUNITY AGAINST ENTAMOEBA HISTOLYTICA C Ivory, K Chadee The Gal-lectin of the protozoan parasite Entamoeba histolytica is a surface molecule required for colonization and invasion in the gut. The goal of this study was to administer a mucosal vaccine to gerbils and mice with the native Gal-lectin and CpG-ODN as adjuvant to augment antigen specific immune responses. CpG motifs are recognized by immune cells to initiate activation of the immune system. Gerbils were vaccinated with CpG-ODN or Gal-lectin + CpG-ODN and challenged with 106 amoeba in the left liver lobe. In order to assess protection at the intestinal level, mice were vaccinated and challenged by intra-cecal amoebic injection. The presence of blocking antibodies against the Gal-lectin was determined with an adherence assay and confirmed by Western blot. Lymphoproliferation and cytokine expression from spleen cells was determined for cellular responses. Pre-challenge sera from vaccinated gerbils inhibited amoeba/CHO rosette formation by 80%. Vaccination with Gal-lectin + CpG-ODN protected gerbils from challenge infection determined by no abscess formation as compared to large abscess formation with viable amoeba in control gerbils. Analysis of cytokine expression by RealTime-PCR demonstrated the presence of Th1 cytokines (IFN-gamma) after challenge in the protected animals. Vaccination with Gal-lectin and CpG-ODN protected animals from amoebic liver abscess formation by a Th1-dependent immune response. We are in the process of analyzing the intestinal disease and protection in the vaccinated and control mice. Preliminary data suggests that Gal-lectin + CpG-ODN mucosal vaccine is protective in the mouse model of amoebic colitis.
Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta