FIG 5.

TMPRSS2 is a crucial protease for replication of IAV but not IBV. (A) Experiment setup. Calu-3 cells were transfected with a TTSP- or KLK-targeting siRNA and infected with IAV or IBV. The percentage of infected cells was quantified by high-content imaging of NP. (B) Impact of protease knockdown on cell viability (gray bars) or virus growth (colored bars), expressed relative to the condition receiving no siRNA. Data are the means ± SEM (n = 3 with four replicates). P values for results versus those with a scrambled siRNA are indicated as follows: *, ≤0.05; ***, ≤0.001; ****, ≤0.0001 (ordinary one-way ANOVA, followed by Dunnett’s test). (C) TMPRSS2 knockdown markedly reduces IAV but not IBV replication, as shown by NP staining. (D) IBV infection in Calu-3 cells receiving combinations of siRNAs.