Development of an enzyme linked immunosorbent assay using recombinant cathepsin B5 antigen for sero-surveillance of bovine tropical fasciolosis

Abstract

Bovine tropical fasciolosis, caused by Fasciola gigantica, is a major parasitic disease in tropical countries responsible for significant production losses in animal husbandry practices. The disease is transmitted by the Radix sp. snails. In the early developmental stage of the parasite, the juveniles and immature flukes cause considerable damage to the liver parenchyma of the bovine host while migrating through the liver. The cathepsin (cat) B5 is a cysteine protease that is present in the excretory-secretory product of the fluke both in immature and adult stages. The early detection of fasciolosis is very critical in effective disease management. In this study, the cathepsin B5 gene from newly excysted juveniles were cloned, sequenced and analyzed. The phylogenetic analysis revealed existence of two distinct clades. The clade I includes cat B 1 to B3 whereas clade II consist of cat B4 to B7. Further, the present study was aimed to develop an enzyme linked immuno sorbent assay (ELISA) using recombinant cat B5 antigen. The developed enzyme immuno assay showed 95.3 % sensitivity and 92.4 % specificity with a cut-off of 60 % percent positive. It revealed weighted Kappa value as 0.768 (95 % CI 0.648-0.889) when compared with ELISA using native cathepsin protein. Hence, the developed assay can be exploited as a potent tool in the diagnosis and sero-surveillance of bovine tropical fasciolosis.