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. 2022 Apr 21;12:850744. doi: 10.3389/fcimb.2022.850744

Figure 5.

Figure 5

U-exo treatment reduces HCoV replication and shows a synergistic effect with IFN-a on HCoV infection. (A) HCT8 cells were infected with HCoV-OC43 at an MOI of 1. After viral attachment, cells were treated with control (Ctl), U-exo (Exo), IFN-α (10 ng/mL), or IFN-α combined with U-exo (IFN-α+Exo) for 5 days, after which viral gene expression levels were measured using RT-qPCR. Transcriptional expression of the viral nucleoprotein (NP) was quantified and the expression levels of viral genes were normalized to GAPDH. (mean ± SD; n = 3). (B) Immunofluorescent staining of HCoV-OC43 at 5 days post infection was visualized by confocal microscopy. Scale bar represents 20 μm. % OC43-stained cells were calculated and the graph shows an average of three independent experiments. Statistical analysis: **p < 0.01; ***p < 0.001, versus Ctl-treated cells. ##p < 0.01; ###p < 0.001, versus IFN-α-treated cells. (C) U-exo were exposed to 1 μg/mL RNase for 1 h and added to cells. Viral NP expression was measured (mean ± SD; n = 3). Statistical analysis: **p < 0.01; versus Ctl-treated cells. #p < 0.05, versus U-exo (Exo)-treated cells. (D) MRC-5 cells were infected with alpha-coronavirus (HCoV-229E) (MOI 1) for 5 days. Supernatant was collected for TCID50 assay. Viral titers were measured using the TCID50 assay and expressed as TCID50/mL (means ± SD; n = 3). Statistical analysis: ***p < 0.001; compared with Ctl-treated cells.