IFNAR1 and infection: To analyze rZIKV-Paraiba viremia, groups of six-to-seven-week-old female IFNAR−/− A129 mice (n = 6) were infected with different doses (102–104 FFU/mouse) of rZIKV-Paraiba or the natural ZIKV-Paraiba isolate, and viral titers in mouse sera were analyzed at days 2 and 4 post-infection (Fig. 2E).