Different cell lines treated with ZIKV pseudotypes. HEK 293T and HUH7 cells infected with pseudotypes produced with different ratios of GFP(+) ZIKV glycoprotein and pNL4.3. (a) 1 µg of GFP(+) ZIKV with a range (1–5 µg) of pNL4.3. (b) 2 µg of GFP(+) ZIKV with a range (1–5 µg) of pNL4.3. (c) 3 µg of GFP(+) ZIKV with a range (1–5 µg) of pNL4.3. (d) 4 µg of GFP(+) ZIKV with a range (1–5 µg) of pNL4.3. (e) 5 µg of GFP(+) ZIKV with a range (1–5 µg) of pNL4.3. Pseudotypes were not infectious in either cell line, regardless of amount of plasmid used. (f) HEK 293 T cells were transfected with a fixed pNL4.3 plasmid amount (2 µg) and fivefold dilutions of the ZIKV GP plasmid (2, 0.4, 0.08, 0.016 and 0.0032 µg). No infectious ZIKV pseudotypes were generated. (g) Mammalian cell lines CHO, BHK-21 and VeroE6 were treated with pseudotypes produced using increasing concentrations of GFP(+) ZIKV plasmid (1–5 µg) in HEK 293 T cells. Again, no infectivity was measured. VSV-G and Δ envelope were used as positive and negative controls, respectively. Graphs show mean±sd of three independent experiments.