Identification of immunodominant antigens for the development of vaccine formulations against bovine cryptosporidiosis

TOMAZIC, MARIELA L.; LOMBARDELLI, JOAQUÍN; POKLEPOVICH, T.; RODRIGUEZ, ANABEL E.; GALARZA, ROXANA; TOLEDO, JONATHAN; GARRO, CARLOS; TIRANTI, KARINA; FLORIN-CHRISTENSEN, M.; SCHNITTGER, LEONHARD

Cartagena

Congreso; Vaccine and Research Development 2016; 2016

The apicomplexan protozoan Cryptosporidium parvum is a causative agent of diarrhea in bovines and humans. As currently there are no available vaccines, the search for antigens to be included in vaccine formulations is essential. Antigens anchored to the parasite surface via glycosylphosphatidylinositol (GPI) are implicated in the invasion of host cells and thus represent potential vaccine candidates. Our work focused on the identification of the GPI-anchored proteome of C. parvum, from which three proteins, Cph1, Cpgp60, and Cpsubl, were selected for further characterization. These antigens were expressed in E. coli and purified by affinity chromatography. By immunoblotting, proteins were exposed to sera of calves (n=12; 1 to 52 days of age) naturally infected by Cryptosporidium sp. Antibodies against the three antigens were detected in all analyzed bovines demonstrating that the antigens are (i) expressed in the parasite; (ii) have conserved B-cell epitopes between isolates, and (iii) are immunodominant. The early detection of specific antibodies (1 to 11 days of age) suggests transfer via colostrum. However, refractometry did not allow confirming this type of transfer. In addition, no association between the presence of antigen-specific antibodies and diarrhea was observed. Conservation of B-cell epitopes was verified for two of the antigens by PCR amplification of coding genes from genomic DNA of 5 geographic isolates and 3 subgenotypes, followed by direct sequencing and in silico analysis. In future studies, these antigens will be tested in vaccine formulations against bovine cryptosporidiosis. Financed by: FonCyt (PICT-2013-1708 and PICT 0695-2012); INTA (PNBIO-1131034 and PNSA-1115053); Fundación Universidad de Morón(PID8-2015).