Figure 7.

Longevity of protection. Wild-type C57BL/6 mice were inoculated with 1 × 10³ pfu Zika virus (ZIKV) i.v. and 3 (A,B) or 8 (C,D) months post i.v. inoculation mice were challenged with 1 × 10³ pfu ZIKV i.c. Mice were weighed and monitored daily (A,C), and on day 7 post i.c. challenge, brains were removed and viral titers were measured by a plaque assay (B,D). Mice were weighed and monitored daily, and on day 7 post i.c. challenge, brains were removed and viral titers were measured by a plaque assay. Groups of naïve mice were used as negative controls. The detection limit for virus in brain was 250 pfu/g organ. Each dot represents an individual animal, and bars represent the medians of the groups. The weight curves depict the group medians. n = 4–5 mice/group, *p < 0.05. Similar results were obtained in BALB/c mice (see Figure S2 in Supplementary Material).