Fig. 4.

Challenge of vaccinated pregnant IFNAR^−/− dams with ZIKV_Natal. a Timeline of vaccination, antibody responses, mating, challenge, viremia, and fetal/placental assays. b Anti-ZIKV serum IgG ELISA titers 4 weeks after vaccination with SCV-ZIKA/CHIK or SCV-cont; (p < 0.001 Kolmogorov–Smirnov tests). c Viremia in the vaccinated mice (n = 10 per group). (For days 2–4 all p < 0.001, Kolmogorov–Smirnov tests). Error bars represent standard error of the mean. d Fetal weights at E17.5 for SCV-vaccinated dams (n = 4–5 dams per group) infected with ZIKV_Natal either at E6.5 or E12.5 (for fetuses n = 36, 33, 35, 43 left to right). SCV-cont vaccinated dams had a lower mean fetal weight than SCV-ZIKA/CHIK vaccinated dams when challenged at E6.5 (p < 0.001, t test, n = 36 and 33). Fetal/placental masses were not included in this graph. e Photographs of selected fetuses (E17.5). Highly deformed fetuses and placenta, and fetal/placental masses are indicated by asterisks (*). The orange lines on the left represent a ruler with 1 mm marks. f Fetal and placenta ZIKV tissue titers at E17.5 from SCV-vaccinated dams (at least three fetal/placental tissues from each of the 4/5 litters were tested); fetal heads or placenta, except * indicating deformed fetal/placental masses. Limit of detection was 1.5 log₁₀CCID₅₀/g. The positive placenta in SCV-cont E6.5 group were derived from three litters. Titers were significantly lower in the SCV-ZIKA/CHIK vaccinated groups compared to the SCV-cont groups p < 0.001 (Kolmogorov–Smirnov test) combining data from F and Pl, and E6.5 and E12.5. g qRT PCR of fetal heads. Three uninfected fetal heads (black squares) were analyzed in triplicate and the highest value plus 3 SD was used as a cutoff (all other data points below the dashed cutoff line are not plotted to scale). *Deformed. Statistics as for f, p = 0.001 combining data from E6.5 and E12.5