ABSTRACT
The coronavirus induced disease 2019 (COVID-19) outbreak caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan (China) in December 2019 is currently spreading rapidly worldwide. We recently reported a laboratory protocol for the diagnosis of SARS-CoV-2 based on real-time reverse transcriptase PCR (RT-PCR) assays using two primer sets, N and N2. On January 30-31, 2020, the protocol and the reagents for these assays were distributed to the local public health institutes and quarantine depots in Japan nationwide, and thereafter SARS-CoV-2 diagnostic testing was initiated. For further validation, the assays were compared with the commercially available kits using the SARS-CoV-2 viral RNA and clinical specimens obtained from COVID19-suspected individuals. The LightMix Modular SARS and Wuhan CoV E-gene (LM S&W-E) assay was highly sensitive for the SARS-CoV-2, as was the N2 set, as both the assays showed consistent results for the clinical specimens. While the LM S&W-E set targets the highly conserved region of E gene in the SARS-CoV and SARS-CoV-2, the N2 set was designed to target specifically the unique region in the SARS-CoV-2 N gene. Therefore, the N2 set exhibits high specificity and sensitivity for SARS-CoV-2 detection. These results indicate that the protocol using the N and N2 sets is comparable to the commercially available kits, and thus is reliable for laboratory diagnosis of COVID-19.