These data together conclusively provide evidence that IL-17 expression during Mtb HN878 infection is required for effective induction of CXCL-13, a chemokine that is key to facilitating productive interactions between cytokine producing CXCR5-expressing T cells and Mtb-infected macrophages for optimal Mtb HN878 control in the lung. This evidence concerns the gene CXCR5 and infection.