CLONING AND EXPRESSION OF A CDNA-ENCODING EPITOPES SHARED BY 15-KILODALTON AND 60-KILODALTON PROTEINS OF CRYPTOSPORIDIUM-PARVUM SPOROZOITES

A CDNA (CP15/60) encoding epitopes of Cryptosporidium parvum 15- and 6 0-kDa sporozoite proteins was isolated and expressed in Escherichia co li toward the goal of developing an immunogen for producing high-titer anticryptosporidial colostrum. Antisera prepared in rats to native C. parvum 15-kDa protein and used to identify the CP15/60 bacteriophage clone recognized both 15- and 60-kDa in vitro translation products der ived from sporozoite RNA. Antisera specific for recombinant CP15/60 an tigen recognized native 15- and 60-kDa C. parvum sporozoite proteins b y immunoblotting and identified both surface and internal antigens on C. parvum sporozoites by immunofluorescence staining. Northern (RNA) a nd Southern blot hybridization experiments using sporozoite RNA and DN A indicated that CP15/60 DNA is transcribed as a single 1.4-kb RNA spe cies from a single-copy gene. Recombinant CP15/60 antigen was recogniz ed by hyperimmune colostrum from cows immunized with C. parvum oocyst- sporozoite protein and by convalescent-phase sera from C. parvum-infec ted calves.