Figure 3.

Strain-dependent effects of fibroblast growth factor 2 (FGF2) on Zika virus (ZIKV) replication. A, Human fetal astrocytes (HFAs) were infected with MR766, PLCal, or PRVABC-59 strains of ZIKV (multiplicity of infection [MOI], 0.3). Two and 3 days after infection, levels of FGF2 in the culture medium were determined by an enzyme-linked immunosorbent assay (i). ZIKV-infected HFAs were cultured in the presence or absence of FGF2 for 2 days, after which viral titers were determined by a plaque assay (ii). ZIKV-infected HFAs were cultured in medium containing a neutralizing mouse anti-FGF2 antibody (Ab) or an isotype-matched mouse Ab. Viral titers in supernatants were determined by a plaque assay (iii). ZIKV-infected HFAs were treated with FGF receptor inhibitor (BGJ398) or dimethyl sulfoxide (DMSO) alone for 2 days, after which viral titers were determined by a plaque assay (iv). Values are expressed relative to control, which was set to 1.0. All statistically significant differences are relative between control and experimentally treated (rFGF2, anti-FGF2 Ab or BGJ398) samples. B and C, ZIKV PRVABC-59–infected HFAs (MOI, 0.3) were cultured in the presence or absence of 12.5 µg/mL recombinant human FGF2 (B) or 2.5 nm BGJ398 or DMSO (C) for 2 days, after which automated high-content immunofluorescence imaging was used to determine the numbers of cells positive for ZIKV E protein. Values are expressed as the mean of 3 independent experiments. Error bars represent standard errors of the mean. *P < .05 and **P < .01, by the Student t test.