Fig. 1: Protective effect of ZPIV after prime or prime/boost vaccination.

a The experimental scheme. Six-week-old female wild-type C57BL/6 mice were intramuscularly (i.m.) injected with alum adjuvant alone, or 1 ug alum-adjuvanted ZPIV with either a one (at 0 week) or two (at 0 and 4 weeks) dose regimen. Two weeks after the last vaccination, females were mated and challenged at embryonic day 9.5 (E9.5) with 6 × 10⁵ PFU ZK-BR and examined at 8 dpi (E17.5). b Representative images of fetal phenotypes per group. The horizontal and vertical lines in the grid mark 5 mm intervals. Note macerated fetuses with abnormal vascular development (arrowheads) and extensive fetal demise after ZIKV challenge of mice that received adjuvant alone. The percentage of dams bearing fetuses with normal phenotype after prime (c) or prime/boost (e) vaccination. The numbers above the individual bar indicate the number of dams without any fetal abnormality over the total number of dams examined per group. The percentage of affected fetuses of total fetuses per group after prime (d) or prime/boost (f) vaccination. The numbers above individual bars indicate the number of affected fetuses over the total number of fetuses per group. The percentage of fetal abnormality was analyzed using Fisher’s exact test. The difference between the alum only and the ZPIV vaccinated group was significant, P < 0.0001 but not between the mock-infected and the prime/boost vaccinated groups (P > 0.05).