Highly Sensitive and Quantitative Diagnosis of SARS-CoV-2 Using a Gold/Platinum Particle-Based Lateral Flow Assay and a Desktop Scanning Electron Microscope

• Published in: Biomedicines Vol. 10; no. 2; p. 447
• Main Authors: Kawasaki, Hideya, Suzuki, Hiromi, Furuhashi, Kazuki, Yamashita, Keita, Ishikawa, Jinko, Nagura, Osanori, Maekawa, Masato, Miwa, Takafumi, Tandou, Takumi, Hariyama, Takahiko
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 15.02.2022; MDPI
• Subjects: Antibodies; Antigens; Cellulose; Copy number; Coronaviruses; COVID-19; desktop scanning electron microscopy; Disease transmission; Infections; Laboratories; lateral flow assay; NanoSuit; Patients; Platinum; Polymerase chain reaction; Reverse transcription; SARS-CoV-2; Scanning electron microscopy; Severe acute respiratory syndrome coronavirus 2; Statistical analysis; United States > US; Japan; Fiji; COVID-19; NanoSuit; SARS-CoV-2; desktop scanning electron microscopy; lateral flow assay
• ISSN: 2227-9059; 2227-9059
• DOI: 10.3390/biomedicines10020447

The gold standard test for identifying SARS-CoV-2, the causative agent of COVID-19, is polymerase chain reaction (PCR). Despite their limited sensitivity, SARS-CoV-2 antigen rapid diagnostic tests are vital tools in the fight against viral spread. Owing to its simplicity and low cost, the lateral flow assay (LFA) is the most extensively used point-of-care diagnostic test. Here, we report a newly designed LFA-NanoSuit method (LNSM) that works in conjunction with desktop scanning electron microscopy (SEM) to detect SARS-CoV-2. LNSM requires no standard SEM treatment, avoids cellulose and residual buffer deformation, and enables the capture of high-resolution images of antibody-labeled gold/platinum particles reacting with SARS-CoV-2 antigens. To assess its applicability, we compared clinical SARS-CoV-2 samples via visual detection of LFA, LSNM detection of LFA, and real-time reverse transcription-PCR (qRT-PCR). Compared to qRT-PCR, LNSM showed 86.7% sensitivity (26/30; 95% confidence interval (CI): 69.28-96.24%) and 93.3% specificity (14/15; 95% CI: 68.05-99.83%) for SARS-CoV-2. In samples with a relatively low SARS-CoV-2 RNA copy number (30 < Ct ≤ 40), the sensitivity of LNSM was greater (73.3%) than that of visual detection (0%). A simple, sensitive, and quantitative LNSM can be used to diagnose SARS-CoV-2.