Abstract
The neutralization of Cryptosporidium muris sporozoites by rabbit antiserum was examined in vitro and in mice. The sporozoites of C. muris could be separated from intact oocysts by repeated centrifugation. The antiserum reacted strongly with three bands of sporozoite antigens at > 200, 78, and 47.5 kilodaltons during immunoblotting. Heat-inactivated antiserum caused morphological changes seen ultrastructurally in the sporozoites. The antiserum reduced the viability of the sporozoites as measured with fluorescein diacetate. When antiserum-treated sporozoites (1×105) were used to inoculate 7-day-old mice per os, endogenously developed parasites were first detected 10 days later by an indirect fluorescence antibody test. When sporozoites treated with normal rabbit serum were used to inoculate mice, parasites were first detected 6 days later. The results suggest that the antiserum partially neutralizes the infectivity of C. muris sporozoites.
