TLR4 and infection: To assess if tlr4 mutant mice could serve as permissive hosts for long-term respiratory infection, we performed intranasal inoculations of WT (C3H/HeN) and tlr4 mutant (C3H/HeJ) mice with a range of inoculums of a modern A. baumannii respiratory isolate, G636, and sacrificed groups of mice every 3 days starting at 24 h post-infection (hpi).