In the course of chronic antigen persistence during viral infection, T cells advance through sequential stages of ‘exhaustion’ that are characterized by expression of multiple inhibitory receptors, including the programmed death-receptor 1 (PD-1) [12], which is associated with T cells retaining proliferative but losing cytokine production capacities, and the T cell immunoglobulin and mucin domain 3 receptor (Tim-3), which is linked to poor proliferative and polyfunctional cytokine production capacities in T cells [12]. The gene discussed is HAVCR2; the disease is viral infectious disease.