Fig. 2: SARS-CoV-2 Omicron and Delta Variant live virus replication in 3D tissue culture systems and 2D cell lines. | Nature

Fig. 2: SARS-CoV-2 Omicron and Delta Variant live virus replication in 3D tissue culture systems and 2D cell lines.

From: Altered TMPRSS2 usage by SARS-CoV-2 Omicron impacts infectivity and fusogenicity

Fig. 2

a, Overview of the viruses and culture systems used. The schematic was created using BioRender.com. be, The spread of infection by replication-competent Omicron versus Delta variants over time in hNECs (b), and Calu-3 (c), Caco-2-Npro (d) and HeLa-A2T2 (e) cells. Viral RNA and/or infectious virus in the supernatant (TCID50) were measured. Data are mean ± s.d. of the technical replicates shown, representative of two independent experiments. Statistical analysis was performed using two-sided unpaired Student’s t-tests; *P < 0.05. h.p.i., hours post-infection. f, Western blot analysis of two live Omicron isolates and one Delta virus isolate in Vero-ACE2/TMPRSS2 cells probed with antibodies against S2, S1 and N, with quantification of the ratio of S2 and S1 to total spike. Data are mean ± s.e.m. of 2–4 biological replicates. g, Vero-ACE2/TMPRSS2 producer cell lysates infected with live isolates probed with antibodies against S2, S1 and N. GAPDH was used as the loading control. A non-specific band above the S2 band is indicated (~). Data are representative of two independent experiments. hj, The subcellular localization of spike in cells infected with SARS-CoV-2 Delta versus Omicron. The subcellular distribution of Omicron and Delta spike proteins in HeLa-ACE2 cells infected with live virus isolates. h, Cells on coverslips were infected for 24 h, fixed and stained with anti-spike, anti-GM130-cis-Golgi, phalloidin 647 and 4′,6′-diamidino-2-phenylindole dihydrochloride (DAPI), and imaged on a Leica TCS SP8 confocal microscope. i, The distance of spike proteins from the nucleus at 24 h after infection. Data points (n = 144 for each virus) are shown along with the median ± interquartile range. j, Quantification of spike–Golgi colocalization in infected cells. Data are mean ± sd. n = 10 for each virus. Values were determined using Pearson’s correlation coefficient. Scale bars, 10 µm (main images) and 1 µm (insets). Statistical analysis was performed using two-sided unpaired Student’s t-tests; NS, not significant.

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