Figure 3.

Zika virus hemifusion efficiency is sensitive to pH but rates are not. Plotted are cumulative distribution functions compiled from single-virus lipid-mixing wait times collected at different pH values and either normalized to fraction of total E-protein-positive particles (a) or normalized by the maximum observed fraction of lipid mixing at each pH value (b). Across the pH range, efficiency changes ∼3 fold: 333/1748 particles at pH 4.6, 145/1514 particles at pH 5.5, 95/1346 particles at pH 5.8, 186/2447 particles at pH 6.1, 68/1447 particles at pH 6.6, and 63/1145 particles at pH 6.9. Kinetic data were compiled from 29 independent fusion streams and replicated with an independent viral preparation. Fraction of total E-protein-positive particles was calculated using mean values measured via immunofluorescence assay (IFA) as described in Supporting Information.