IFNGR1 and infection: Surprisingly, we found that KitW-sh/W-sh Ifnar1−/− Ifngr1+/+ mice born to naïve mothers were particularly vulnerable to s.c. DENV1 challenge, and all the infected mice died by day 8 post-infection in contrast to infection by i.p. injection where all the mice survived (Supplementary Figure S3), suggesting that the route of infection was critical to the influence of immunity and that skin-resident MCs are likely protective.