Immunodiagnostic potency of homologous antigens for natural Haemonchus contortus infection in small ruminants in plate and paperenzyme linked immunosorbent assay

Abstract

The objective of this study was to characterize Haemonchus contortus antigens, and to standardize and evaluate indirect plate and dot-ELISA using homologous antigens in the small ruminants. Electrophoretic separation of somatic antigen in reducing condition on 15% polyacrylamide gel resolved into 16 proteins of molecular weight ranging from 14-100 kDa. Two step ethanolic extraction of the supernatant of in-vitro culture of H. contortus yielded excretory-secretory (E-S) antigen/ cathepsin L cysteine proteinase of molecular weight 28 kDa. The animals (Goats=103; Sheep=91) were broadly kept into post-mortem (PM) and faecal examined groups and further sub-grouped based on mono or multiply helminths infection. At many occasion, the somatic antigen found to cross reacts with other helminths parasites thus minimizing the specificity of the selected tests and antigens. There was no any direct correlation between the parasites load and ELISA reactivity pattern. The prevalence rate of haemonchosis was 55.7 (34/61) in goats/ 47.6 (40/84) % in sheep as per PM examination while it was 45.63 (47/103) in goats/ 41.76% (38/91) in sheep and 36.89 (38/103) in goats/ 35.16% (32/91) in sheep using E-S antigen based plate and dot-ELISA, respectively. With E-S antigen, the overall % sensitivity, specificity, positive and negative predictive values of plate-ELISA was 89.74 (goats)/ 80.95 (sheep), 81.25 (goats)/ 91.84 (sheep), 74.47 (goats)/ 89.47 (sheep), 92.86 (goats)/ 84.91 (sheep), respectively while for dot-ELISA it was 66.67 (goats)/ 61.9 (sheep), 81.25 (goats)/ 87.76 (sheep), 68.42 (goats)/ 81.25 (sheep), 80 (goats)/ 72.88 (sheep), respectively, so the tests and E-S antigen can be recommended for the detection haemonchosis in the small ruminants.