Figure 2

(A) The antiviral activity of selected peptides against influenza A/Puerto Rico/8/34(H1N1) by qRT-PCR. The peptides were pre-treated with A/Puerto Rico/8/34 virus at 100 TCID₅₀ for 30 min, and then the virus-peptides mixture was transferred to the cells for another 1 h. At 24 h post-infection, the matrix gene was detected by quantitative real-time PCR. Statistical significance of the data with the virus group was defined as p < 0.05 (*p < 0.01, **p < 0.001). (B) The plaque reduction assay of C20-Jp-Hp against influenza A/Puerto Rico/8/34(H1N1). The cells were divided into four groups. Group 1 (Pretreatment of cell): peptides were added to cell monolayers for 30 min before influenza virus adsorption at 37 °C under 5% CO₂. Group 2 (Pretreatment of virus): peptides were pre-incubated with influenza virus for 30 min at 37 °C before added into the cells. Group 3 (During infection): virus A/PR/8/34 (100 TCID₅₀) with peptide (10 μM) was simultaneously added to cells. Group 4 (After infection): peptides were added to cell monolayers after influenza virus adsorption at 37 °C under 5% CO₂ for 30 min. After incubation at 37 °C 5% CO₂ for 48 h, the plaques from each group were counted. Arbidol (5 μM) was used as positive control. (C) In vitro time-of-addition studies on anti-influenza viral activity of the C20-Jp-Hp and C20-Hp-Jp by CPE reduction assay in MDCK cells. Arbidol was used as positive control. Each data was performed in triplicate, and three independent determinations were carried out.