IFNAR1 and Zika virus infectious disease: For example, experiments using a breeding scheme that enabled the examination of pregnant dams that carry a mixture of fetuses that express type I IFN signaling (Ifnar1+/–) or do not express type I IFN signaling (Ifnar1−/−) within the same uterus found that only Ifnar1+/– was resorbed after ZIKV infection during early pregnancy, whereas their Ifnar1−/− littermates continued to develop (17).