Figure 2.

Papaya pulp extract inhibits ZIKV binding to the cell surface. (a) Schematic representation of time-of-drug-addition assay used to characterize antiviral activity of papaya pulp extract (1000 µg/mL) on ZIKV^GFP infection of A549 cells. Orange arrows indicate the presence of pulp extract during the infection. Flow cytometric analysis of GFP expression in A549 cells infected with ZIKV^GFP at MOI of 2 PFU/cell under the experimental conditions shown in the top. (b) A549 cells were infected with ZIKV at MOI of 2 PFU/cell for 1 h at 4 °C with or without 1000 µg/mL of papaya pulp extract. Pineapple juice and mango pulp extracts (1000 µg/mL) have been used as negative controls. EGCG (100 µM) was used as a positive control. After 24 h of infection, results of GFP-expression in ZIKV^GFP-infected A549 cells under the experimental conditions, shown in the top, were analyzed by flow cytometry assay. The data represent the means ± SD of four independent experiments and are expressed as relative values compared to the mock-treated control. Statistical analyses were performed using a one-way ANOVA and Dunnett’s test for multiple comparisons (**** p < 0.0001; n.s. = not significant).