FIG 3.

Presence of the 350-kb duplication is associated with attenuation in the mouse model of infection. C57BL/6×DBA2 F1 mice were infected via aerosol with the HN878-27 and HN878-45 strains, the latter of which contains the 350-kb duplication. (A and B) Bacterial numbers were monitored at the indicated time points postinfection by harvesting and plating the lungs of infected mice. Results are expressed as the average log₁₀ CFU (± standard deviations) obtained from five mice at each time point (*, P < 0.01 by Student's t test). In panel B, strains H37Rv and G4B1.2 were also used to infect animals, with only two time points analyzed. Initial CFU/lung were 100, 98, 98, and 51 for H37Rv, HN878-27, HN878-45, and G4B1.2, respectively. (C) Kaplan-Meier survival curves of groups of 11 mice infected with isolates HN878-27 (empty squares), HN878-45 (filled squares), G4B1.2 (filled circles), or the laboratory strain H37Rv (open triangles). The Mann-Whitney test was used to determine the statistical significance of observed differences in survival (GraphPad Prism, v3.0; GraphPad Software, CA). For HN878-27, the median survival time was 149 days versus 226 days for HN878-45 (P = 0.0152). The strains that harbor the 350-kb duplication are HN878-45 and GB41.2 (filled squares and circles, respectively).