CD4 and tuberculosis: Tri:ChAd:TB immunization differed significantly from its monovalent counterpart in its capacity to markedly boost TB10.4 and RpfB-specific CD4+ and CD8+ T cells in BCG-primed hosts, with a twofold increase in TB10.4 and RpfB-specific CD4+ T cells and 4- and 20-fold increase in TB10.4 and RpfB-specific CD8+ T cells, respectively, compared to those boosted with its monovalent counterpart (Fig. 2D, E).