Fig. 8: Membrane-tethered mucins restrict infection of multiple respiratory viruses.

a–c, Calu-3 mucin GOF cells were infected with (a) SARS-CoV-2, (b) HKU5-SARS-CoV-S or (c) MERS-CoV at an MOI of 0.1. At 24 h postinfection, viral titers were quantified by plaque assay. The dotted line is the NTG average, n = 3 biological replicates. Significance was calculated by a two-sided t-test between each GOF cell line versus NTG. d, As a–c, except on WT Calu-3 cells pretreated with StcE. n = 3 biological replicates, two-sided t-tests were performed for the indicated pairs. e, Calu-3 cells were treated with StcE or left untreated and then infected with the indicated virus for 24 h. Relative levels of viral gene copies were quantified by RT–qPCR. Displayed are n = 4 (HCoV-229E), n = 10 (HCoV-OC43), n = 15 (Influenza A virus, PR8), n = 5 (PIV3) and n = 10 (RSV) biological replicates. Two-sided t-tests were performed for the indicated pairs. f,g. Mucin-overexpressing Calu-3 cells were infected with HCoV-229E or PIV3, and relative levels of viral gene copies were quantified 24 h postinfection by RT–qPCR. n = 3 biological replicates, the dotted line is the NTG average. Significance was calculated by a two-sided t-test between each GOF cell line versus NTG. h, PIV3 infection of the indicated GOF Calu-3 cells, with and without StcE treatment, at 48 h postinfection quantifying GFP⁺ cells. Displayed is a single time point from the experiment shown in Extended Data Fig. 10a. Displayed are n = 5 biological replicates, two-sided t-tests were performed for the indicated pairs. Dotted lines indicate the NTG average for two separate guides, with (upper) and without (lower) StcE treatment. Error bars denote mean ± s.e.m. NS, not significant; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.