Fig. 4

Acute CS treatment blocks in vitro SARS-CoV-2 replication in differentiated primary airway epithelium. HBECs, fully differentiated into airway epithelium by culture at air–liquid interface, were subjected to acute sham- or CS-exposure prior to SARS-CoV-2 infection. Cells were infected via apical inoculation with SARS-CoV-2 at 0.05 PFU/cell MOI for 1 h at 37C, washed to remove unbound virus, and infections were incubated for 24 h, 48 h, and 72 h. A Samples are collected for RNA purification and RT-qPCR to detect the level of SARS-CoV-2 nucleocapsid gene in infected cells by following the procedure described in method session. The SARS-CoV-2 N gene level is lower in 48 h and 72 h post-infected CS-treated cells compare to Sham-treated cells (n = 3 technique replicates). * = P < 0.05. ** = P < 0.01. CS cigarette smoke. B The infected HBEC cells were sampled by addition of 200 uL fresh media to the apical side of the transwell to collect all the progeny virus that is released from the infected cells. The amount of the progeny viruses was tittered by plaque assay as described in method session. CS-treated cells generated less SARS-CoV-2 progeny compared to Sham-treated cells after 48 and 72 h of infection (n = 4). * = P < 0.05. CS cigarette smoke