Vikas Yadav

and 6 more

Goat warble fly infestation (GWFI) is an economically important myiasis caused by larvae of Przhevalskiana silenus (Diptera, Oestridae), prevalent in countries of the Mediterranean Basin and Indian subcontinent. GWFI is characterized by the presence of subcutaneous warbles at the lumbar and sacral region of dorsum in the infested animal. The early larval instars (L1 and L2) remain inaccessible to physical detection due to their small size and subcutaneous presence thus causing prolonged economic loss to animal productivity. The early diagnostic intervention is needed during the disease monitoring and prophylactic management for effective control of the disease. The present study has developed an in-house dot-ELISA for the serodiagnosis of GWFI based on recombinant Hypodermin C (rHyC) antigen of Przhevalskiana silenus, expressed in E. coli. The purified protein was used for optimizing dot-ELISA in a checkerboard titration using goat warble fly infested serum as known positive. The optimized conditions require 188 ng of protein/dot, 1:800 dilution of serum sample, 1:4000 dilution of anti-goat IgG conjugate and 5% skim milk powder in phosphate buffer saline as blocking buffer. The assay was found to have a diagnostic sensitivity and specificity of 97.3% and 95.8%, respectively. The inter-rater reliability of dot ELISA with rHyC indirect ELISA was found to be almost perfect with a Cohen’s kappa index of 0.973. Further testing at ambient temperature (18 oC) and shorter incubation steps (30 min) supported suitability of the assay for field diagnosis of GWFI. The rHyC protein based Dot-ELISA was evaluated using random field serum samples suspected for GWFI. The present study provides the first report of a sensitive and specific dot-ELISA for early diagnosis of GWFI which is rapid and cost effective. The test may provide an effective tool for sustainable control of GWFI.