Copro-antigen capture ELISA for the detection ofTeladorsagia(Ostertagia)circumcinctain sheep: improvement of specificity by heat treatment

Abstract

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk A copro-antigen capture ELISA for the detection of Teladorsagia circumcincta infection in sheep was developed and evaluated. Experiments with faeces from worm-free sheep, that had been spiked with known concentrations of excretory-secretory (E-S) antigen indicated that a positive signal was generated with 180 ng of E-S/ml. A nested design, based on 8 infected and 8 worm-free sheep, was employed to assess the stages during sample preparation contributing to variation in signal from the assay. This showed that 87% of the variance in the optical density readings (ODs) was directly explained by infection status. Variation between individual sheep within infection groups, and between samples at various stages in the assay, collectively accounted for the remaining variance. Initial evaluation of specificity using faeces from animals carrying a range of monospecific infections indicated cross-reactivity with Haemonchus contortus and Nematodirus spathiger. However, by treating the supernatant from faeces for 20 min at 100 xC, the cross-reactive signal was eliminated whilst the specific signal was largely preserved. Heat treatment of faeces from 12 non-infected sheep, 12 sheep with T. circumcincta and 6 with H. contortus resulted in sensitivity being increased from 66 . 7 to 85 . 7 %, and specificity from 62 . 5 to 87 . 5%. OD values showed a significant positive relationship with adult worm burdens, although at low infection intensities there was some overlap between infected and worm-free animals. We discuss the application of CC-ELISAs in facilitating selective chemotherapy of sheep, as a means of avoiding the development of anthelmintic resistance in pastoral regions where sheep are farmed on a large scale.

A Coproantigen Diagnostic Test for Strongyloides Infection

“…More recently coproantigen tests have used antiserum raised to E/S antigens for the diagnosis of animal nematode infections. In general this approach has proved to be more useful [6], [20], [22].…”

“…In the case of nematode infections, a number of assays have been reported for the detection of animal host parasites, including Necator americanus [21], Ancylostoma ceylanicum [20], Teladorsagia circumcincta [22] and Heligmosomoides polygyrus , [6]. There have also been reports where assay sensitivity and/or specificity was unsatisfactory e.g.…”

Diagnosis of Oesophagostomum columbianum infection in goat by indirect enzyme linked immunosorbent assay

“…The short comings of antibody ELISA in the diagnosis of helminth infections would best be overcome using antigen detection ELISA. Copro-ELISA assay could be the best possible tool for detection of current infection of gastrointestinal parasites and attempts in this regard have already been made (Johnson et al, 2004;Jas et al, 2010). The standardized assay offers the potential for its development as one of good diagnostic tools for oesophagostomosis.…”

“…The infective L 3 were obtained by culturing (Soulsby, 1982) the eggs separated from the adult female worms recovered from the caecum and colon of slaughtered goats (Johnson et al, 2004). The L 3 at the dose rate of 600 per kg body wt.…”

“…For preparation of crude somatic antigen (CSAg) O. columbianum from the caecum and colon of freshly slaughtered goats was collected (Johnson et al, 2004) in a Petri dish containing 0.15 M phosphate buffer saline (PBS), pH-7.2. The worms were washed 4 -5 times in the same buffer and finally 300 worms were homogenized in 10 ml of cooled 0.15 M PBS (pH-7.2) containing 25 mM phenylmethyl sulfonyl fluoride (PMSF) and 24 mM ethylene-diamine tetraaceticacid (EDTA) in a glass tissue homogenizer.…”