Protection of Calves Against Cryptosporidiosis by Hyperimmunization of Pregnant Cattle Colostrum using Oocyst Whole Antigens

BACKGROUND: Cryptosporidium parvum is a coccidian parasite with worldwide distribution. OBJECTIVES: It is considered one of the most important causes of diarrhea in many vertebrate species and im munocompromised humans. Due to the lack of effective treatment of cryptosporidiosis, protection strategy against this species can be focused on encouraging the immune system through vaccine development. METHODS: For this aim, we prepared oocysts lysate as a whole antigen vaccine candidate (420 μg) and immunized 3 pregnant cows 4 times every 2 weeks from 70 days to parturition. As a control group, 3 unimmunized pregnant cows were used. After parturition, each calf was fed with colostrum of his dam and challenged at 12h of age with 1×10^7 C. parvum oocysts. RESULTS: In contrast to the test group, the calves in the control group developed severe watery diarrhea with excretion of oocysts from 4 days post-infection. The calves in the test group, which received the hyperimmune colostrum, showed no clinical signs and a significant reduction in oocysts excretion. CONCLUSIONS: The whole antigen prepared from oocysts of C. parvum can be considered a suitable candidate for immunizing pregnant cows producing hyperimmune colostrum.