Characterizing role of exosomes against SARS-CoV-2 in vitro.

(A) Infection level in Fig 3D against number of donor A549ACE2+ or A549 cells (in 15 cm plates). (B) Number of infectious particles measured by plaque assay from apical washes every 24 h for 72 h of HAECs infected with SARS-CoV-2 alone (red), SARS-CoV-2 and ACE2+ exosomes (blue), SARS-CoV-2 and ACE2− exosomes (green), and SARS-CoV-2 with neutralizing Ab (gray); # corresponds to number of input plates (15 cm). (C) Representative immunofluorescence images of Vero E6 cells infected with SARS-CoV-2 where the cells were stimulated/pretreated with PBS, CpG, or nAb from Fig 3F. Scale bar: 1.25 mm. (D) Infection level 24 hpi with SARS-CoV-2 of ATG16L1 KD or non-targeting shRNA control (NT) A549ACE2+ cells. (E) Infection level 24 hpi with SARS-CoV-2 in ATG16L1 KD or NT control Vero E6 cells. Virus dilution in (D) and (E) corresponds to the step in a 2-fold dilution series of SARS-CoV-2 (MOI: 0.01). (F) Infection level of Vero E6 cells following infection with media alone, SARS-CoV-2 alone, or SARS-CoV-2 mixed with supernatant from Vero E6 cells stimulated with CpG-A or enriched exosomes from CpG-A stimulated Vero E6 cells. Error bars show mean ± SEM, with measurements taken from distinct samples. Underlying data can be found in S1 Data. F One-way ANOVA with Dunnett’s post-test compared to SARS-CoV-2. **** P ≤ 0.0001. HAEC, human airway epithelial culture; hpi, hours post infection; KD, knockdown; ns, not significant; SARS‑CoV‑2, Severe Acute Respiratory Syndrome Coronavirus 2. (TIFF)