Development of Lateral Flow Assay for Point-of-Care Diagnosis of Trypanosomosis in Equines

Trypanosomosis, commonly known as “Surra” in Indian subcontinent caused by Trypanosoma evansi, is a worldwide parasitic disease of wild and domestic animals. The disease is transmitted mechanically by biting and interrupted feeding of infected animals by hematophagous flies. The diagnostic methods available for this disease require high-end instruments and skilled manpower and are time-consuming. In the present investigation, we attempted an immunoassay based on gold nanoparticles for diagnosis of T. evansi infection in equines. Antibodies to horse IgG were raised in rabbits and conjugated to gold nanoparticles after purification with the protein-A column. The soluble whole cell lysate antigen was prepared from purified T. evansi parasites and coated as test line on nitrocellulose membrane laminates, along with control line to detect anti-Trypanosoma antibodies. The experimental and field serum samples were tested and evaluated to determine the sensitivity and specificity of the assay. The antigen-specific antibodies were detected in experimental serum samples between 10 and 21 days post infection by the lateral flow assay (LFA). The LFA results showed 96.3% sensitivity and 93.9% specificity comparable with enzyme-linked immunosorbent assay. The study suggests that the LFA can be used as a point-of-care diagnostic method in the field, which does not require any specialized instrument for the detection of T. evansi infection in animals.