Cryptosporidium parvum is a significant human pathogen whose incidence has increased dramatically in the last decade and that currently infects approximately 10% of the AIDS patients in the U.S. Mortality due to this parasite exceeds 60% of infected immunocompromised patients. No therapeutic drugs are available; however, bovine colostrum that contains anti-Cryptosporidium antibodies has proven efficacious in animal studies and patients. The availability of cloned, protective antigens would remove major obstacles in quantifying protective antibody and in reproducing vaccines for a passive antibody product. Cloned proteins from a lambda gt11 expression library have been selected as potential protective antigens based on the localization of these antigens on sporozoites. In this proposal, these antigens will be screened for recognition by protective antibody. Positive clones will be used to affinity purify antibody that, in turn, will be assayed for protective activity in vitro. Antibody will also be affinity purified from the cognate sporozoite proteins (using western blotting of native gels) to estimate the protection provided by antibodies to native proteins. The long term goal is to use a cloned antigen in the production and quantitation of anti-Cryptosporidium passive antibody product for treatment of infected, immunocompromised patients.
