Figure 1.

Phyllanthus phillyreifolius extract exhibits antiviral activity against African and Asian strains of Zika virus (ZIKV). (A) A549 cells were incubated with two-fold serial dilutions (1000 to 2 µg/mL) of plant extract for 72 h. Cell viability was evaluated using an MTT assay. (B) A549 cells were infected with ZIKV^GFP at MOI of 1 in presence of different concentrations (250, 125, 62.5, 31.25, 15.60, 7.80, 3.90, and 2 µg/mL) of P. phillyreifolius. Flow cytometric analysis of GFP fluorescence was performed 24 h post-infection. A549 cells were infected with ZIKV-PF13 at MOI of 2 and continuously incubated with increasing concentrations of P. phillyreifolius (PP). (C) The amount of viral genomic RNA in ZIKV-PF13-infected A549 cells was determined by RT-qPCR. (D) ZIKV progeny production was quantified by plaque-forming assay. The results shown are means ± SD of four independent experiments and are expressed as relative value compared to untreated infected cells. ** p < 0.01; *** p < 0.001, n.s. = not significant. (E) Immunofluorescence analysis of viral protein expression in ZIKV-PF13-infected A549 cells. The ZIKV (red) and nuclei (blue) were visualized by fluorescence microscopy. Scale bars are 50 μm. Results from a representative experiment (n = 3 repeats) are shown.