Mohamad Reza Mokhber Dezfouli - Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Faisal Zarghami - Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Sadegh Rahbari - Department of Parasitology, Faculty of Veterinary Medicine, University Of Tehran, Tehran, Iran
Elahe Ebrahimzadeh Abkooh - Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.
Samad Lotfollahzadeh - Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Sirous Sadeghian Chaleshtori - Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Parviz Shayan - Department of Parasitology, Iranian Research Center of Ticks and Tick-borne Diseases, Faculty of Veterinary Medicine, University of Tehran,

 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.

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