|Reinhardt, Timothy - Tim|
Submitted to: Veterinary Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/18/2006
Publication Date: 11/30/2006
Citation: Akili, D., Heidari, M., Welter, L.M., Reinhardt, T.A., Harp, J.A. 2006. Characterization of a factor from bovine intestine that protects against Cryptosporidium parvum infection. Veterinary Parasitology. 142(1-2):168-172. Interpretive Summary: Crytosporidium parvum is an intestinal parasite that causes diarrheal disease in calves. This disease is costly to dairy and beef producers, and the disease can also spread to humans by contaminated water and food. In previous studies, we showed that resistance to C. parvum infection could be transferred to young animals feeding them by intestinal mucosa from resistant adult animals. In this study, we identified the active component from the adult mucosa as a protein with similarities to an enzyme found in many species of animals, including humans. These findings help to clarify the importance of age-related changes in susceptibility to C. parvum and may lead to strategies to reduce disease incidence and increase profitability for producers.
Technical Abstract: Crytosporidium parvum is a protozoan parasite that causes intestinal infection in a variety of mammals. We have previously described a factor in adult rat or adult bovine intestinal mucosa that protects against C. parvum infection when fed to susceptible infant rats. This factor is absent in intestinal mucosa from bovine calves. In the present study, we describe the further characterization of the active component of bovine intestinal mucosa. The ability to protect infant rats against C. parvum infection was found to be associated with the extrinsic membrane protein fraction of the intestinal mucosa. Extrinsic membrane preparations from adult cows, adult rats, and calves were separated by SDS-PAGE. A band with apparent molecular mass of 54 kD was seen in preparations from adult rat and cow, but not calf. Protein was transferred to PVDF membrane and from this the band was excised and subjected to N-terminal sequence analysis using a gas-phase protein sequenator. A 15-amino acid consensus sequence was generated with homology to leucine aminopeptidase (LAP). Purified LAP was purchased from a commercial source and tested for ability to protect infant rats against C. parvum infection. Rats fed LAP from 7-11 days of age and challenged with C. parvum at 9 days were significantly less infected than controls upon necropsy 15 days of age. These data suggest that a protein with N terminal sequence homology to LAP may reduce susceptibility of infant rats to C. parvum infection.