Fig. 1. MHV68^POS mice are more resistant to Mtb growth and dissemination.

(A) For this study, adult C57BL/6 mice were intranasally infected with 10⁴ PFU of MHV68, or vehicle alone. Eighteen days later, all mice were aerogenically infected with ~80 CFU of virulent Mtb (H37Rv). On post-Mtb infection days 17 and 38, mice from each group were euthanized and the lungs, spleen and MLNs were removed for either CFU burden assessment or measuring the frequency of IFNγ-producing T cells. (B) Mtb burdens in the lungs and spleen from indicated groups were assessed by plating serial dilutions of homogenized organs on 7H11. Shown for each time is the mean number of CFU (log10) present in 3–4 mice per group per time point. Error bars represent ± SD; asterisks indicate that a significant difference between MHV68^POS and MHV68^NEG mice was observed at the indicated time point (i.e., P ≤ 0.05 as determined using Student's t-test). Results are representative of three independent experiments.