Effect of BCG immunization on a 16-week <i>id</i> BCG challenge.

<p>Timeline is shown in (<b>a</b>). BALB/c mice were immunized <i>id</i> with 1×10⁴ CFU BCG. Naïve mice received no immunization. 16 weeks later all mice were challenged with 10³ CFU BCG, except the (BCG+(I+R)(no challenge)) group. This group and the BCG+(I+R) group received 6 weeks of isoniazid and rifampicin (starting 8 weeks post initial BCG immunization). In the BCG+(I+R) group, there was a 2 week wash-out period between cessation of antibiotics and subsequent BCG challenge. (<b>b</b>) shows the splenic IFN-γ ELISpot responses to PPD and TB10.3, in naïve, BCG-vaccinated, and BCG+(I+R)(no challenge) animals, 4 weeks post BCG challenge. Whiskers represent minimum to maximum values, boxes the interquartile range, and the bars the median values for each group (*<i>P</i><0.05, **<i>P</i><0.01, “non-significant”, ND. <i>n</i> = 10, except for BCG+(I+R); <i>n</i> = 2). Ears and LNs were harvested 4 weeks after BCG challenge and processed for CFU quantification. Log₁₀ BCG CFU of challenge are shown, for groups 1 (Naïve), 2 (BCG) and 3 (BCG+(I+R)). For group 4 (BCG+(I+R) no challenge), the ear and LN CFU correspond to the CFU remaining from the priming BCG immunization (zero in all animals). Individual data points for each mouse are shown. Bars represent the median per group. (<b>c</b>) Ears (*<i>P</i><0.05,**<i>P</i><0.01, <i>n</i> = 10); (<b>d</b>) LNs (**<i>P</i><0.01, <i>n</i> = 10).