Diagnostic innovations in Equine Parasitology: a Nanogold-ELISA for sensitive serodiagnosis of migratory strongylus vulgaris larvae infections

Strongylus vulgaris, a devastating parasitic nematode in equids, causes life-threatening verminous aneurysms that are challenging to diagnose early. This study pioneered integrating nanotechnology into an indirect enzyme-linked immunosorbent assay (i-ELISA) system to enhance the sensitivity and specificity for detecting S. vulgaris larval antigens in equine serum samples, with PCR confirmation of the species. A conventional i-ELISA and an innovative nano-based ELISA were developed using excretory-secretory antigens from adult S. vulgaris worms. The nano-ELISA incorporated gold nanoparticles (17.4-41.4 nm) conjugated with detection antibodies, enabling remarkable signal amplification. Of the 120 examined equines, 100 (83.33%) were positive for S. vulgaris infection. A conventional i-ELISA and an innovative nano-ELISA incorporating 17.4-41.4 nm gold nanoparticles were optimized using S. vulgaris excretory-secretory antigens. Both assays demonstrated high specificity, with no cross-reactivity against sera from animals infected with other helminth parasites. Remarkably, optical density (OD) readings from both i-ELISAs exhibited a positive quantitative correlation with infection intensity. The i-ELISA OD ranged from 0.45-0.74 (G3), 0.75-0.94 (G2), to 0.95-2.5 (G1). The nano-ELISA showed enhanced signal amplification, with OD ranging from 0.40-0.84 (G3), 0.85-0.99 (G2), to 1.0-3.5 (G1). This nanotechnology-amplified ELISA opens new, highly sensitive, and specific techniques for parasitic diagnosis in equine medicine. Its superior performance, facilitated by signal-amplifying gold nanoparticles, illuminates nanotechnology's potential in revolutionizing parasitological diagnostics for enhanced animal health and welfare management.