Amebiasis contributes to approximately 50 million cases of life-threatening dysentery world-wide. Comparison of the lectins from Entamoeba histolytica (pathogenic) and Entamoeba dispar (nonpathogenic) was undertaken to elucidate the differential roles of this molecule in invasion versus colonization. Surface lectin was less abundant on axenic E. dispar than on axenic E. histolytica, commensurate with differences in lectin (heavy and light subunits) RNA when assessed by semiquantitative RT-PCR. The 1G7 epitope, which falls within the immunodominant and immuno-protective cysteine-rich region (480-900), was absent on axenic E. dispar. Indirect immunofluorescence, transient transection of COS7, and immunoprecipitation demonstrated that the 1G7 epitope was conserved in the nonpathogenic lectin homologue but not exposed on live E. dispar trophozoites. Hg12 (E. histolytica) and Dhg12 (E. dispar) lectin homologues demonstrated comparable high-affinity binding to multivalent GalNAc19BSA. These data provide evidence for relative gene and conformational regulation of the E. dispar lectin.
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