Polyclonal antibody based coproantigen detection immunoassay for diagnosis of Oesophagostomum columbianum infection in goats

A polyclonal antibody based coproantigen detection enzyme linked immunosorbent assay (cAg-ELISA) for diagnosis of experimental and natural Oesophagostomum columbianum infection in goats was developed and evaluated. Adult O. columbianum worms, collected from the caecum and colon of slaughtered goats, were triturated and cultured for obtaining infective third stage larvae (L3) and also used for preparation of excretory–secretory antigen (ESAg). Experimental goats were orally infected each with 600 L3/kg of the body weight. Filter sterilized faecal supernatant, i.e. the coproantigen (cAg) was harvested from the rectal faeces of all the infected goats, on alternate days from day-5 till day-31 after the infection. Hyperimmune serum (HIS) against ESAg of O. columbianum was raised in rabbits. Molecular and antigenic characterization of ES products of O. columbianum by HIS revealed that 50 and 39 kDa polypeptides were immuno-dominant. Coproantigen detection ELISA was standardized by using the cAg as coating antigen and its subsequent binding with the HIS against ESAg of O. columbianum. The sensitivity, specificity and accuracy of the standardized assay were determined by evaluating the assay on the faecal supernatant of 96 slaughtered goats taking into consideration their recorded parasitological status in respect of the abomasal and the intestinal parasites. The cAg-ELISA detected the prepatent oesophagostomosis on 20–24-day-post-infection with a sensitivity, specificity and accuracy of 88, 89.13 and 88.54%, respectively. The assay is relatively easy to perform and would serve as a reliable tool for detection of caprine nodular oesophagostomosis.