Design of a lateral flow assay targeting the conserved NIID_2019-nCoV_N gene region for molecular viral diagnosis.

SARS-CoV-2, the causative agent of the COVID-19 pandemic, remains a significant threat to global public health. Therefore, rapid and accurate detection of the virus continues to be of critical importance. Among the specific gene regions of SARS-CoV-2, the Nucleocapsid (N) protein gene is one of the most frequently targeted for viral identification, with NIID_2019-nCOV_N being a notable example. While reverse transcriptase polymerase chain reaction (RT-PCR) remains the gold standard for diagnosis, alternative molecular detection methods are still limited. In this study, a lateral flow assay (LFA) was developed for the detection of a conserved gene region within NIID_2019-nCOV_N. Gold nanoparticles (AuNPs) were employed to enable visual detection, and the assay was designed based on nucleic acid hybridization principles. Two different membrane types (M17 and M12), three oligonucleotide probe concentrations (2, 4, and 8 µM) conjugated to AuNPs, and the assay's limit of detection (LOD) were evaluated. The target sequence from NIID_2019-nCOV_N was successfully detected by the naked eye within 5-6 min. No significant differences in performance were observed between the two membrane types across all probe concentrations, and the LOD was determined to be 1 pM. Consequently, the nucleic acid-based lateral flow assay (NABLFA) designed in this study, which targets a specific conserved base sequence, demonstrated high potential for rapid and sensitive molecular detection of SARS-CoV-2. Furthermore, this approach may be adapted for the identification of emerging viral variants or future outbreaks.