IFNAR1 and viral infectious disease: Our findings demonstrating direct, IL-15-independent effects of IFNε on NK cells are consistent with reports that NK cell expression of the type I IFN receptor (IFNAR) is required to mediate their cytolytic activity and IFNγ production in other sites during viral infections (Gill et al, 2011; Martinez et al, 2008; Zhu et al, 2008).