IFNAR1 and infection: Infection with wild type Sindbis virus strain AR 339 (SINV) in adult C57BL/6 mice (B6- WT) leads to a short viremia with no evidence of virus in CNS, as all B6-WT mice survive the challenge without showing symptoms of disease (Supplementary Figures 1A,B), despite the virus being lethal in B6-IFNAR1 KO (Supplementary Figure 1C).