TLR9 and viral infectious disease: However, resident corneal immune cells (Hamrah et al., 2002, 2003b, 2003c; Brissette-Storkus et al., 2002), such as cDCs and macrophages, do not express TLR9 in the cornea, and their contribution to secretion of type I IFNs upon viral infections is limited (Noisakran and Carr, 2000; Wuest et al., 2006; Chintakuntlawar et al., 2010; Conrady et al., 2011), suggesting that other hitherto unidentified bone marrow (BM)-derived cells may contribute to corneal antiviral immunity.