ULTRASTRUCTURAL EFFECTS OF LACTOFERRIN BINDING ON GIARDIA-LAMBLIA TROPHOZOITES

Lactoferrin and its derived N-terminal peptide may be important host d efenses against Giardia lamblia. We showed earlier that lactoferrin an d the derived peptides have potent giardicidal activity in vitro. Usin g indirect immunofluorescence, we now demonstrate binding of lactoferr in and the peptides to the live trophozoite surface. Iron strongly inh ibited binding of lactoferrin, and decreased binding of the peptides, while certain divalent metal ions decreased binding of all forms by ab out half. Lactoferrin and the peptides caused striking and complex mor phologic changes in the trophozoite plasmalemma, endomembranes and cyt oskeleton, and increased the electron density of the lysosome-like per ipheral vacuoles.