Protection of calves against cryptosporidiosis with immune bovine colostrum induced by a Cryptosporidium parvum recombinant protein

The purpose of the study was to determine if immunization with a recombinan t protein (rC7) of Cryptosporidium parvum would induce immune bovine colost rum that protected calves against cryptosporidiosis following oral challeng e with C, parvum oocysts. Late gestation Holstein cows with low titers of a ntibody to the p23 antigen of C. parvum were immunized three times with 300 mu g affinity purified rC7 C, parvum recombinant protein (immune cows), or left nonimmunized (control cows). Colostrum was obtained from each cow in both groups and partitioned into identical aliquots of pooled immune colost rum or pooled control colostrum. Twelve calves obtained at birth received e ither immune or control colostrum within the first 2 h, and again at 12 and 24 h of age. Each calf was challenged orally with 10(7) C. parvum oocysts at 12 h of age and monitored for signs of cryptosporidiosis. All six calves administered pooled control colostrum developed severe diarrhea (mean tota l fecal volume = 8447 +/- 5600 ml) and shed an average of 1.87 +/- 1.66 x 1 0(12) C, parvum oocysts. None of the six calves administered pooled immune colostrum developed diarrhea (mean total fecal volume = 740 +/- 750 mi, p < 0.05), and shed significantly fewer oocysts (3.05 +/- 2.26 x 10(9), p < 0. 05). The absence of diarrhea and 2.79 log(10) (99.8%) reduction in oocyst e xcretion indicates that immune bovine colostrum induced by immunization wit h C. parvum recombinant protein rC7 provided substantial protection against cryptosporidiosis in neonatal calves. (C) 1999 Elsevier Science Ltd. All r ights reserved.