IFNAR1 and infection: On the contrary, infection with ECTV∆CrmD, a virus lacking a viral antagonist of TNF signaling (29), still exhibited an attenuated phenotype in IFNAR−/− mice (Fig. 6B), demonstrating that these animals were still capable of mounting protective responses, and ECTV needs to block the TNF-mediated pathway to become virulent in IFNAR−/− mice.