IFNAR1 and infection: In addition, using 16S quantitative PCR (qPCR) analysis we confirmed a significant increase in Enterobacteriaceae in the stool samples of the PR8-infected WT mice, but not in the PR8-infected Ifnar1-/- mice (Fig 1D), however no significant difference was found between WT and Ifnar1-/- mice at day 0 prior to infection (Fig 1D).