TLR3 and bacterial infectious disease: We found that exposure to the TLR3 and RIG-I ligand, poly I:C, was sufficient to impair pulmonary clearance of secondary bacterial infection, using two clinically-relevant gram-positive pathogens, S. pneumoniae and MRSA, as the second “hit.” There appeared to be a dose-dependent effect of poly I:C on the level of impairment, with 1 dose of poly I:C being sufficient to observe at least a trend towards impaired clearance, but 3 daily doses of poly I:C needed to achieve statistically significant levels of impairment.