ISG15 and infection: By comparison, IFN-β, RIG-I, and ISG15 mRNAs accumulated to higher levels in C57BL/6 and Rag1−/− adult mice after the infection with NoV than with NoVΔB2 (Fig. 6B), indicating that expression of VSR-B2 from NoV did not inhibit the induction of the IFN response in adult mice, consistent with the findings from MEFs (Fig. 2).