To understand the nature of CD4+ T cell-derived signatures involved in infection and disease development, we examined and analyzed whole genome expression profiles of purified CD4+ T cells from healthy individuals (HD), two distinct populations with latent infection (with low or high IFN-γ levels, LTBL/LTBH) and untreated TB patients. The gene discussed is IFNG; the disease is disease arising from reactivation of latent virus.