Evaluation of a polyclonal antibody based sandwich ELISA for the detection of faecal antigens in Schistosoma spindale infection in bovines

摘要

Schistosomosis is a common parasitic infection in animals prevalent in cattle in Asia and Africa, where it is estimated that at least 165 million animals are infected. Out of the 10 species reported to naturally infect cattle only Schistosoma nasale and Schistosoma spindale have received particular attention, because of their recognized veterinary significance. Although animal schistosomes may, under rare conditions favouring intensive transmission, act as important pathogens in endemic areas occur at a subclinical level, causing significant losses due to long term effects on animal growth and productivity. The detection of Schistosoma antigens in serum or stool could be more valuable in diagnosis, hence early treatment before irreparable damage. In this study, fresh adult worms of S. spindale were collected from the mesenteric blood vessels, whole worm antigen was prepared. These were immunized to rabbit and guinea pig to raise antibodies against S. spindale. Polyclonal antibodies of rabbit are further used as primary capture antibodies to coat ELISA plates. The capture of antibodies of guinea pig was conjugation with horse reddish peroxidase was used as secondary antibodies. Sandwich ELISA was performed to detect Schistosoma antigens in faecal samples collected from a total of 86 infected cattle and buffaloes. The working dilutions of capture antibody, detecting antibody and conjugate were found to be 1:32, 1:20 and 1:5,000 respectively by checker board titration method. The dilution of faecal supernatant antigens of S. spindale antibodies was 1:80. Out of 86 faecal samples, 77 samples were positive by Sandwich ELISA indicating 89.54 % infection. Where as in control samples none of the samples was positive. In mixed infection out of 20 samples positive for fasciola, amphistome and hydatid, Out of 20 samples 2 samples were positive indicating 10 % infection rate. The overall sensitivity of this test is 88.65 % and specificity was 90.90 %. It could be concluded that sandwich ELISA is a rapid, easy and sensitive assay for diagnosis of S. spindale infection in bovines.