Expression and purification of NS1 protein for designing a lateral flow assay-based aptamer-antibody.

Dengue fever, a mosquito-borne viral disease, presents with mild symptoms in most patients but is characterized by dengue hemorrhagic fever (DHF) in severe cases. Current diagnostic methods are expensive and take time to process. Diagnostic testing is currently limited, particularly in low-resource environments. In this work, we provide the development of a rapid diagnostic test for dengue using a lateral flow immunoassay (LFA) strip using an aptamer-antibody sandwich to detect the NS1 protein. The LFA includes an antibody capture zone and a conjugate pad with an aptamer linked to gold nanoparticles (AuNPs). A biotin-labeled complementary aptamer is immobilized in the control zone on streptavidin, forming a sandwich format. In the presence of the NS1 protein, it binds to the antibody and the aptamer-AuNP complex, producing a visible bichromatic line to indicate a positive result. The LFA detects DENV2 NS1 at concentrations as low as 5.2 ng/mL (95% CI: 4.6-5.8) in buffer. With a detection limit of 6.1 ng/mL (95% CI: 5.5-6.8) in spiked human serum, the test may offer a promising approach, pending further clinical evaluation approach for early dengue diagnosis.