With respect to responses against Rpf, a putative TB reactivation marker [14,45], we report, for the first time in a HIV-TB co-infect cohort, that the highest and most frequent responses (including IFN-γ and TNF-α) observed were in the HTB+ group, suggesting that these individuals may have experienced reactivation as this protein is required for the resuscitation of MTB from dormancy [46]. The gene discussed is IFNG; the disease is tuberculosis.