SARS-CoV-2 antigen rapid diagnostic test enhanced with silver amplification technology

Miyakawa, K.; Funabashi, R.; Yamaoka, Y.; Jeremiah, S. S.; Katada, J.; Wada, A.; Takei, T.; Shimizu, K.; Ozawa, H.; Kawakami, C.; Usuku, S.; Tanaka, N.; Yamazaki, E.; Shimizu, H.; Okabe, N.; Hasegawa, H.; Ryo, A.

Rapid diagnosis of COVID-19 is essential for instituting measures to prevent viral spread. SARS-CoV-2 antigen rapid diagnostic test (Ag-RDT) based on lateral flow immunochromatography assay (LFIA) principle can visually indicate the presence of SARS-CoV-2 antigens as a band. Ag-RDT is clinically promising as a point-of-care testing because it can give results in a short time without the need for special equipment. Although various antigen capture LFIAs are now available for rapid diagnosis for SARS-CoV-2 infection, they face the problems of low sensitivity. We have previously developed highly specific monoclonal antibodies (mAb) against SARS-CoV-2 nucleocapsid protein (NP) and in this study, we have employed these mAbs to develop a new LFIA that can detect SARS-CoV-2 NP in nasopharyngeal swab samples with higher sensitivity by combining them with silver amplification technology. We also compared the performance of our Ag-RDT against the commercially available Ag-RDTs using clinical samples to find that our newly developed LFIA performed best among tested, highlighting the superiority of silver amplification technology.