Evaluation of a diagnostic ELISA for insect bite hypersensitivity in horses using recombinant Obsoletus complex allergens.
Authors: van der Meide Nathalie M A, Savelkoul Huub F J, Meulenbroeks Chantal, Ducro Bart J, Tijhaar Edwin
Journal: Veterinary journal (London, England : 1997)
Summary
Insect bite hypersensitivity (IBH) in horses is predominantly caused by Culicoides midges of the Obsoletus complex, yet diagnostic confirmation has historically relied on whole body extract (WBE) antigens, which can be labour-intensive and variable in quality. Van der Meide and colleagues evaluated seven individual recombinant allergen proteins (Cul o 1–7) derived from Obsoletus complex midges against WBE using IgE ELISA testing in 194 horses with clinical IBH and 175 unaffected controls, assessing sensitivity, specificity and diagnostic accuracy. Whilst WBE demonstrated superior performance overall, a three-allergen combination panel (Combi-1: Cul o 3, 5 and 7) achieved 89% sensitivity and specificity—matching the diagnostic accuracy of WBE—with two four-allergen combinations also performing comparably, though winter sampling reduced detection rates to approximately 70%. These findings are significant for practitioners because recombinant allergen panels offer standardised, reproducible diagnostic tools that could streamline IBH confirmation without the technical limitations of whole body extract preparation. For farriers, vets and physiotherapists managing horses with seasonal or year-round hypersensitivity reactions, access to validated, reliable serological testing via recombinant allergens may improve diagnostic certainty and inform more targeted management strategies, though practitioners should be aware that winter sampling may yield false negatives.
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Practical Takeaways
- •A simplified three-allergen ELISA panel (Cul o 3, 5, 7) offers practical diagnostic accuracy equivalent to whole body extract testing for confirming IBH in horses with clinical signs
- •Recombinant allergen testing may be more standardizable and reproducible than whole body extract, potentially improving consistency across diagnostic laboratories
- •Winter sampling shows reduced sensitivity; consider spring-summer testing for optimal diagnostic accuracy when screening horses for Obsoletus complex hypersensitivity
Key Findings
- •Whole body extract (WBE) achieved the highest diagnostic accuracy, but combination of three recombinant allergens (Combi-1: Cul o 3, 5, 7) achieved 89% sensitivity and 89% specificity
- •Combi-1 (Cul o 3, 5, 7) performed comparably to WBE and could potentially replace it in IgE ELISA diagnostics for IBH
- •Recombinant allergen combinations showed reduced performance in winter-collected samples but still identified over 70% of IBH-affected horses
- •Individual recombinant allergens Cul o 2, 3, and 5 performed best among single allergen tests after WBE