Inhibitory effect of Qing-Fei-Pai-Du decoction on coronavirus in vitro

Qing-Fei-Pai-Du decoction (QFPDD) is a combination of traditional Chinese medicine and plays an important role in the treatment of coronavirus disease 2019 (COVID-19). This study investigated the inhibitory effect of QFPDD on coronavirus replication and antiviral mechanism. The cytotoxicity of QFPDD was determined by PrestoBlue cell viability assay. Quantitive reverse transcription PCR (qRT-PCR) and immunofluorescence assay (IF) were used to detect the inhibitory effects of QFPDD on coronavirus at RNA and protein levels. qRT-PCR was used to detect the adsorption and penetration of coronavirus after QFPDD treatment. The effects of QFPDD on interferon (IFN) and interferon-stimulated genes (ISGs) were also detected by qRT-PCR. The results showed that QFPDD inhibited coronavirus at RNA and protein levels in a dose-dependent manner at non-toxic concentration, and QFPDD targeted in the early stages of coronavirus infection cycle. Preliminary mechanism studies have shown that QFPDD can directly block the virus entry into the cell by inhibiting virus adsorption, and QFPDD can also play an antiviral role by up-regulating the expression of IFN and ISGs. These results indicate QFPDD as a drug potential to treat coronavirus infection.