a, b, Vero E6 cells are shown at 24 h after infection with mock virus (a) or 2019-nCoV (b). c, d, Mock-virus-infected (c) or 2019-nCoV-infected (d) samples were stained with rabbit serum raised against recombinant SARSr-CoV Rp3 N protein (red) and DAPI (blue). The experiment was conducted twice independently with similar results. e, The ratio of the number of reads related to 2019-nCoV among the total number of virus-related reads in metagenomics analysis of supernatants from Vero E6 cell cultures. f, Virus growth in Vero E6 cells. g, Viral particles in the ultrathin sections were imaged using electron microscopy at 200 kV. The sample was from virus-infected Vero E6 cells. The inset shows the viral particles in an intra-cytosolic vacuole.