Eosinophils extravasate from the peripheral blood into the lung during RSV infection. The details of how the virus regulates the recruited eosinophils to help combat the infection remain to be determined. Phipps and coworkers show that some TLR-7 is present on the outer surface of the mouse eosinophil. However, most TLR-7 resides inside the cell, presumably in an endosomal and/or lysosomal compartment. Once viral ssRNA comes in contact with TLR-7, activation of an IRF7-dependent signaling pathway occurs, which eventually results in the release of the cell's preformed granule mediators (eg, EPX) and newly generated cytokines (eg, IFN-β) that contributeto the host's antiviral response. The activated eosinophil also increases its expression of important surface proteins like CD11b/ITGAM.