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 (۴۲۰ μg) and immun-ized ۳ pregnant cows ۴ times every ۲ weeks from ۷۰ days to parturition. As a control group, ۳ unimmunized pregnant cows were used. After parturition, each calf was fed with colostrum of his dam and challenged at ۱۲h of age with ۱×۱۰۷C. parvum oocysts. RESULTS: In contrast to the test group, the calves in the control group developed severe watery diarrhea with excretion of oocysts from ۴ 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.

کلیدواژه ها:

Cryptosporidium parvum ، Hyperimmune colostrum ، Immunization ، Oocyst whole antigen ، Pas-sive vaccine