Efficacy of glutathione-S-transferase purified antigen of the gastro-intestinal nematode Haemonchus contortus in diagnosis of sheep haemonchosis.

Haemonchus contortus is one of the most pathogenic and economically important parasites of sheep. Different H. contortus antigens; crude somatic antigen (CSA), excretory/secretory antigen (ESA), crude larval antigen (CLA), glutathione-S-transferase antigen (GST) and recombinant protein (rhcp 26/23) were prepared and characterized using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blot. The antigens were immunologically evaluated through indirect enzyme linked immunosorbent assay (ELISA) for diagnosis of haemonchosis in experimentally and naturally infected sheep. Analysis of the resultant bands of SDS-PAGE demonstrated that 13, 6, 11, 2 and 1 protein bands from CSA, ESA, CLA, GST and rhcp 26/23, respectively and analysis of the resultant bands of western blot showed that 13, 6, 4 and 1 reactive bands detected from CSA, ESA, CLA and GST, respectively. The results of ELISA of different antigens revealed that sero-prevelance of CSA, ESA, CLA, GST and rhcp 26/23 were 78.51, 82.34, 85.319, 45.319 and 90.8% respectively, sensitivity were 100, 90, 100, 96.66 and 90%, respectively and specificity were 0, 70, 10, 70 and 6.66%, respectively with diagnostic potency were 50, 80, 55, 83.33 and 48.33%, respectively. Statistical analysis using Chi square test found that GST is the best one that can be used. The cross reactivity of GST antigen, crude Fasciola antigen and crude Moniezia antigen tested versus their homologous hyper immune sera at different dilutions using ELISA. The current study reported that GST antigen could be considered as a promising antigen for diagnosis of haemonchosis.