This exhaustion, demonstrated by an experiment conducted by Habiba et al., is characterized by a shift to a profile of diminished cytokine secretion 21 days after the infection following the initial pro-inflammatory T cell response (CD4+ and T helper 17 (Th17) T cells secreting interferon-γ (IFN-γ), Tumor Necrosis Factor-α (TNF-α) and IL-17), as shown in Figure 1. The gene discussed is CD4; the disease is infection.