SARS-CoV-2 enters faster on Calu-3 cells than SARS-CoV and entry speed is increased by the multibasic cleavage site. ( A ) SARS-CoV PP and SARS-CoV-2 PP infectivity on VeroE6 and Calu-3 cells. ( B and C ) SARS-CoV PP and SARS-CoV-2 PP entry route on Calu-3 cells. Cells were pretreated with a concentration range of camostat ( B ) or E64D ( C ) to inhibit serine proteases and cathepsins, respectively. T-test was performed for statistical analysis at the highest concentration. * P
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