Throughout the infection all TB10.4 3–11 and TB10.4 74.88 epitope specific CD8 and CD4 T cells displayed an effector phenotype in agreement with a previous study which also showed that both CD4 and CD8 T cell bulk populations in the lungs of chronically infected mice expressed a cell surface phenotype consistent with that of effector T cells (Fig. 4 and [25]). Here, CD4 is linked to infection.