ACTB and infection: We then used a neutralizing antibody against the SARS-CoV-2 S protein [33] and remdesivir, a well-known inhibitor of SARS-CoV-2 replication, to perform parallel tests as described above in Vero-E6 cells [34], and detected the viral RNA level in the cell lysate relative to the β-actin level at 1 h and 6 h post-infection.