Immunological characterization of a 17-kDa antigen from Cryptosporidium parvum recognized early by mucosal IgA antibodies.

Cryptosporidium parvum antigens were characterized by immunoblot analysis of sera and intestinal secretions of BALB/c mice orally infected with 10(5) oocysts. A major band at 17 kDa under non-reduced conditions and at 18 kDa under reduced conditions was recognized by anti-C. parvum IgA and IgG in serum and intestinal secretions from day 15 post-infection. This recognition persisted throughout the experiment (day 30). Mouse-serum antibodies raised against the 17-kDa purified antigen (P17) showed no cross-reactivity with other C. parvum antigens. Immunofluorescence study revealed that this antigen is located on the sporozoite. It is suggested that this antigen could be a good candidate for studies of mucosal immune response to C. parvum and for vaccination.