Aerosol Mycobacterium tuberculosis infection

Frozen aliquots of Mtb H37Rv were thawed and diluted in PBS with 0.05% Tween 80. Mice were infected with either low-dose (100–200 CFU) or high-dose (~1000 CFU) of Mtb using a nose-only aerosol exposure chamber (In-Tox Products, NM), equipped with a miniHEART nebulizer (WestMed, Tucson, AZ), as previously described [11]. A day 1 CFU count was performed to determine the infecting dose. At indicated time-points after infection, bacterial loads in the lungs and spleens were determined by plating serial dilutions of tissue homogenate on Middlebrook 7H11 agar plates (BD, Franklin Lakes, NJ), and colonies were counted after 2–3 weeks of incubation at 37°C.