TLR7 and susceptibility to pneumonia measurement: We have shown that infection with pneumonia virus of mice (58), a mouse-specific Pneumovirus of the same genus as RSV, predisposes to severe bronchiolitis in Tlr7-deficient mice, while the adoptive transfer of Tlr7-sufficient pDC to Tlr7-deficient mice confers protection, implicating a critical role for TLR7 on pDCs.