Further experiments investigating the CD4 T cell landscape may provide more apparent differences between the two infection cohorts and Tcf1+ and Tcf1– populations, given both the role of T follicular helper cells in chronic infection and that previous studies performing CD4 depletion have demonstrated that the terminally differentiated Tcf1– population shrinks but not in the proliferation-competent CD8 T cells (7, 22). The gene discussed is TCF7; the disease is infection.