FIGURE 2.

Effect of mu‐sEVs and mucus‐containing sEVs on HNEC infection by SARS‐CoV‐2. (A) Effect of preincubation of viral particles with different concentrations (10⁷–10⁹) of mu‐sEVs or with EV‐deprived mucus on SARS‐CoV‐2 infection (10 μl of viral inoculum, ∼2.04 × 10⁵ TCID₅₀/ml) at the apical pole of HNECs after removal of recipient cell mucus. Intracellular SARS‐CoV‐2 RNA was extracted 72 h post‐infection and quantified by RT‐qPCR. Results were normalized to 18S rRNA, then to mucus‐free control and viral particle preincubation with PBS alone (black bar). They are expressed as mean ± SEM of two independent experiments. **p < 0.01, ***p < 0.001. (B) Dynamics of SARS‐CoV‐2 RNA production at the apical pole of HNECs, as assessed by RT‐qPCR. Results were normalized to the viral RNA level 4 h post‐infection for each condition and expressed as log₁₀ mean ± SEM of two independent experiments. *p < 0.05, **p < 0.01 (Mann‐Whitney U‐test versus extracellular SARS‐CoV‐2 RNA levels in the presence of recipient cell mucus 72 h post‐infection (blue line))