Sialic Acid-Specific Lectin-Mediated Adhesion of Tritrichomonas foetus and Tritrichomonas mobilensis

Tritrichomonas foetus is an obligate parasite of the bovine urogenital tract producing infection associated with inflammatory changes, abortion, and infertility, Tritrichomonas mobilensis was isolated from squirrel monkey colon, and symptoms involve diarrheal complications. Both tritrichomonads produced hemagglutinins with the properties of sialic acid-specific lectins. Assays on the adherence of these protozoans to Chinese hamster ovary (CHO) cells and to bovine cervical and monkey colon mucus were performed to assess the function of the lectins in adhesion. Sialic acid at concentration as low as 2 mM inhibited the adhesion to CHO cells, less effectively to the mucus. Predigestion with Clostridium perfringens sialidase prevented the adhesion to both epithelial cells and the mucus. Inhibition of endogenous sialidases with 2,3-dehydro-2-deoxy-NeuAc increased the adhesion of T. mobilensis to CHO cells. Specific anti-T. foetus lectin (TFL) and anti-T. mobilensis lectin (TML) antibodies inhibited adhesion of the trichomonads to the epithelial cells and to the mucus. TFL histochemistry disclosed the presence of lectin ligands on keratinized vaginal epithelia, cervical mucosa, and mucin and on endometrial glands and their secretions. TML histochemistry showed reactivity with the luminal membranes of colonic glandular epithelium and less with the colonic mucin. Both lectins bound to the surface membrane of CHO cells. Anti-lectin antibodies showed granular cytoplasmic and strong membrane localization of the lectins in both tritrichomonads. Although the 2 tritrichomonads have different habitats, the results indicate that both these protozoa use lectins with sialic acid specificity for adhesion to mucosal surfaces.