Antibody-induced formation of caps in Toxoplasma gondii.

Trophozoites of Toxoplasma gondii from mouse peritoneal exudate move their surface membrane antigens towards one pole of the cell when incubated with antibodies. The phenomenon may be induced in up to 50% of incubated parasites. It is prevented by some metabolic inhibitors and low temperatures (0-4 degrees C). These properties do not change in parasites subpassaged after repeated incubation with antibodies.