RESUMO
An 18-20 kDa Cryptosporidium coproantigen [18-20 CCA] had been detected in the stool of infected humans and calves. A purified, electroeluted and concentrated 18-20 kDa antigen was tested in Ussing chamber. Electric parameters were tested before and after the addition of this antigen. A significant increase in the short circuit current [Isc] was detected. The enterotoxic effect of 18-20 kDa CCA was time and dose dependent, heat labile and CI- dependent. The detected change in the short circuit was not detected when the 18-20 kDa antigen was incubated with its monospecific antibodies. These results indicated an enterotoxic activity of the 18-20 kDa antigen secreted from the released parasite and detected in stool of infected humans and calves. Additionally, they may help in developing an appropriate anti-secretory therapy for the intractable diarrhea caused by cryptosporidiosis