The therapeutic action of monoclonal antibodies against a surface glycoprotein of Giardia muris.

Twenty-three monoclonal antibodies (mAbs) against Giardia muris were obtained in two fusions using spleen cells of immunized mice. Similarly, the fusion of mesenteric lymph node (MLN) cells of an infected mouse yielded 15 mAbs. Three mAbs arising from spleen cells and two from MLN (all five were IgM) were able to kill trophozoites in the presence of guinea-pig complement (GPC). They can agglutinate trophozoites and also impair the movement of the flagella in the absence of GPC. I.p. treatment of mice with mAb 45C on Days -1, 1, 3 and 5 of infection significantly reduced the intestinal parasite burden. Indirect immunofluorescence assays on live and fixed trophozoites revealed that the cytotoxic mAbs were directed against antigens located on the periphery of the body, the sucking disc, the flagella and the ventro-lateral flange. In Western blots, our mAbs recognized major 36,200 and 30,300 MW glycoproteins located on the surface of the parasite.