Validation of an in-house Sarcosystis fusiformis glycoprotein-based ELISA for the serodiagnosis of sarcocystosis in buffaloes

Abstract Sarcocystosis is a highly prevalent parasitic disease with great economic significance in the intermediate hosts, mainly causing asymptomatic infection. The main aim of this study is the molecular characterization and phylogenetic analysis of the Sarcocystis species and developing of a highly sensitive and specific diagnostic tool based on the Concanavalin-A (Con-A) affinity purified S . fusiformis glycoprotein antigen (SF-GlcNAc). Successfully Sarcocystis fusiformis (S. fusiformis) was detected only one type, which was closely related to the strains previously isolated in Egypt. The sensitivity and specificity of the purified antigen containing N-acetyl glucosamine (GlcNAc) were assessed using a set of negative (n = 40), positive (n = 45), and control serum samples from buffaloes. The specificity of the SF-GlcNAc antigen was detected using different sera samples positive for multiple parasitic infections, including toxoplasmosis, cryptosporidiosis, coccidiosis, giardiasis, and blastocistosis with indirect ELISA. The receiver operating characteristic curves and area under the curve demonstrated that SF-GlcNAc-ELISA is 95.56% sensitive, 82.5% specific, and exhibits 89.4% diagnostic accuracy compared with crude whole cyst antigen-ELISA (68.89% sensitivity, 67.5% specificity and 68.24% diagnostic accuracy). SF-GlcNAc-ELISA showed only 12% cross-reactivity with the sera from toxoplasmosis cases with 88% relative specificity. Collectively, our study introduces an SF-GlcNAc-based ELISA as a highly accurate, low-cost method for the serodiagnosis of bovine sarcocystosis.