Biotin/avidin-free sandwich aptamer-based lateral flow assay (ALFA) for the diagnosis of Trichomonas vaginalis

Abstract

The development of low-cost, rapid point-of-care tests (POCT) for the detection of the parasite Trichomonas vaginalis is listed in the recent WHO global research priorities for sexually transmitted infections (STIs). Aiming to contribute to this call and aid in ending STIs as a public health threat, we report the development of a DNA aptamer-based POCT for T. vaginalis. Herein, we report an aptamer-based lateral flow assay (ALFA) based on dual aptamers for the detection of T. vaginalis. This is the first report of an ALFA that does not rely on biotin/streptavidin for either capture or reporter molecule. Aptamer capture and recognition relies on the use of an UV-crosslinked aminated capture aptamer on the nitrocellulose membrane and gold nanoparticles (AuNPs) functionalized with a thioctic acid-modified reporter aptamer. The developed ALFA has an estimated laboratory production cost of less than 1 € per test, with the running buffer and the ALFA strip stable for at least 1 year at room temperature (22 °C). The assay requires three simple operator steps from sample procurement to result with a 15-minute runtime. The developed ALFA can detect down to 1.6 × 105 T. vaginalis per mL and shows no cross-reactivity to common vaginal microorganisms and no matrix effect from clinical cervicovaginal lavage (CVL) samples is observed. Preliminary clinical evaluation using CVLs demonstrated that the assay has perfect concordance with wetmount assay on matching vaginal swabs. The developed rapid test offers a simple, stable, and low-cost diagnostic test for T. vaginalis.