At day 42 the expression of the following genes was at a relatively higher level in M. bovis AF2122/97 infected animals than in M. tuberculosis H37Rv infected animals (Fig. 4B): CXCL9, a previously described potential TB biomarker50,57; mediator of mycobacterial-induced cytokine production in macrophages CD18058; and the chemokine CXCL11. Here, CXCL9 is linked to tuberculosis.