Development of a lateral flow immunoassay for bovine trypanosomosis using a chimeric protein derived from African and South American trypanosoma vivax strains.

Bovine trypanosomosis (BT), primarily caused by Trypanosoma vivax (T. vivax), remains a significant constraint on livestock productivity across sub-Saharan Africa and Latin America, with increasing reports of emergence in new regions. Rapid and reliable diagnostic tools are crucial to enable timely treatment and control, particularly in field settings where laboratory infrastructure is limited. This study describes the development and evaluation of a novel diagnostic platform for T. vivax based on a chimeric recombinant antigen (QIAFAM), engineered from invariant surface glycoproteins (ISGs) of both African and South American T. vivax strains. Diagnostic performance of QIAFAM was first assessed using an indirect ELISA (QIAFAM-ELISA) with 212 bovine serum samples. Compared to a previously developed ISG antigen mixture (TvISGAf + TvISGAm), the QIAFAM-ELISA showed higher sensitivity (95.3% vs. 89.6%) and comparable specificity (92.6% vs. 93.8%). In light of these findings, a lateral flow immunoassay employing QIAFAM (QIAFAM-LF) was developed using a double-paratope design. Evaluation of the QIAFAM-LF using 108 serum samples classified by parasitological microscopy and/or PCR demonstrated high diagnostic accuracy, with sensitivity and specificity values of 98.1% and 90.9%, respectively, together with strong agreement with QIAFAM-ELISA results (κ = 0.889). This is the first reported device that combines African and South American components into a unique, highly conserved chimeric antigen. This dual-origin antigen design enhances geographic applicability and supports the use of QIAFAM-based assays as scalable, field-deployable diagnostic tools for surveillance and control of T. vivax infection in endemic and emerging regions worldwide.