FIGURE 3.

The rate of cell infection with Zika virus (ZIKV) and the speed of ZIKV-containing endocytotic vesicles depend on the ZIKV strain. (A) The percentages of ZIKV-positive astrocytes and neurons, infected with three different ZIKV strains [Brazil 2016 (Brazil), French Polynesia 2013 (FP), and Uganda #976 1947 (Uganda)] at 12 h post-infection (p.i.) and 84 h p.i. (means ± SEM; one-way ANOVA, *p < 0.05). The percentages were determined by counting the number of immunolabeled cells versus the number of all DAPI-stained nuclei (representing single cells). Data were collected from one experiment performed in duplicate. Results are based on a total of 10⁴ cells/group, counted in 16 independent fields of view (the numbers of cells counted per strain: 858–1805 astrocytes and 4882–5765 neurons). The percentages of ZIKV-positive astrocytes and neurons are different at both 12 h p.i. and 84 h p.i. in both cell types and increase with time. Note that the rate of cell infection depends on the ZIKV strain. (B) In astrocytes, the average speed of endocytotic vesicles increased with longer times p.i. for ZIKV-Br- and ZIKV-Ug-laden vesicles, while the average speed of ZIKV-FP-laden vesicles decreased. In neurons, the average vesicle speed exhibited the most prominent increase at 36 h p.i., regardless of the virus strain, and then declined the most in ZIKV-FP-laden vesicles. (C) A schematic representation of the higher speed of ZIKV-Br- and ZIKV-Ug-laden vesicles, as compared to the speed of ZIKV-FP-laden vesicles. The ZIKV is depicted as pink dots. Modified from Jorgačevski et al. (2019) with permission.