Protective efficacy of recombinant Cryptosporidium parvum CpPRP1 sushi domain against C. tyzzeri infection in mice.

Until now, there are no completely effective parasite-specific pharmaceuticals or immunotherapies for treatment against the zoonotic cryptosporidiosis. Sushi domain (CpSushi) is an important functional domain in Cryptosporidium parvum putative rhoptry protein-1 (CpPRP1), which is the only reported C. parvum rhoptry protein and may play key role in the course of invasion. Here, a 708-bp fragment encoding the CpSushi domain was amplified and expressed in E. coli. Immunofluorescence detection showed that CpSushi was located on the surface of C. parvum oocysts and the apical pole to the sporozoites that belonged to the position of rhoptry. Three-week-old female ICR mice were used for detecting the immunoreactions and immunoprotection of recombinant CpSushi (rCpSushi) to artificial C. tyzzeri infection. The results indicated that a significant increase of anti-CpSushi antibody response was induced by the recombinant protein. Compared to blank, Tris-EDTA (TE) buffer and adjuvant controls mice, rCpSushi-immunized mice produced specific spleen cell proliferation as well as enhanced IL4, IL5, IL12p70 and TNF-α production in vitro. The reduction rate of parasites shedding in stool in mice immunized with rCpSushi was 68.91% after challenging with C. tyzzeri. These results suggest that CpSushi could be a new promising cryptosporidiosis vaccine candidate antigen composition.