Fig. 4: SR-B1 mediates SARS-CoV-2 attachment and entry.

a, 293T cells transfected with GFP-SR-B1 were exposed to SARS-CoV-2pp in solutions containing 6 μg ml⁻¹ HDL at 4 °C for 30 min for attachment to the cell surface. All images were obtained by confocal microscopy. The scale bar indicates 10 μm. b, Huh-7 cells transfected with siSR-B1 were exposed to SARS-CoV-2 (MOI = 0.1) in 10% FBS at 4 °C for 10 min. All images were obtained by confocal microscopy. The scale bar indicates 40 μm. c,d, Huh-7 cells transfected with siSR-B1 (c) or HA-SR-B1 (d) were infected with SARS-CoV-2 for 1 h, and the cells were collected 3 h after infection for detecting the gene copy number of the virus by RT–qPCR (upper graph) or intracellular SARS-CoV-2 staining by confocal microscopy using an anti-HA antibody (lower images). The scale bar indicates 40 μm in c and 10 μm in d. n = 3 independent biological experiments. P = 0.0002 for HDL siCtrl versus HDL siSR-B1 (c), P = 0.0076 for HDL HA-V versus HDL HA-SR-B1 by two-tailed Student’s t-tests. e, For attachment, 293T cells transfected with HA-SR-B1 were exposed to SARS-2-S in solutions containing 0.1% FBS or 6 μg ml⁻¹ HDL at 4 °C for 30 min. The cells were washed and detached before immunolabeling for flow cytometry. f, Huh-7 cells preincubated with ITX 5061 (25 μM) or BLT-1 (25 μM) were inoculated with SARS-CoV-2pp in solutions containing 6 μg ml⁻¹ HDL, and pseudotyped viral entry was analysed by luciferase activity at 48 h after infection. Signals obtained without compounds in 0.1% FBS were used for normalization. n = 3 independent biological experiments. P < 0.0001 for HDL versus HDL ITX 5061, P = 0.0003 for HDL versus HDL BLT-1 by one-way ANOVA and Bonferroni’s post hoc analysis. g, Huh-7 cells preincubated with ITX 5061 (25 μM) were infected with SARS-CoV-2 (MOI = 0.001) in solutions containing 6 μg ml⁻¹ HDL at the indicated concentrations for 1 h, and the cells were collected to detect the gene copy number of the virus with RT–qPCR at 24 h after infection. n = 3 independent biological experiments. P < 0.0001 for HDL versus HDL ITX 5061 by two-tailed Student’s t-tests. h, Representative images of immunohistochemical staining for ACE2 and SR-B1, which was performed on a paraffin-embedded human normal organ tissue microarray with antibodies against ACE2 or SR-B1, and counterstaining with hematoxylin was performed to show nuclei (blue). The scale bars indicate 200 μm or 20 μm, as indicated. The results shown are representative of two independent biological experiments. The data are the mean ± s.e.m. **P < 0.01, ***P < 0.001.

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