In addition, blocking the PD-1/PD-1 L pathway augmented the functionality of LCMV-specific CD4+ T cells in a chronic model of infection, resulting in the increased production of IFN-γ, an increase in the frequency of multifunctional CD4+ T cells and the improvement and recovery of exhausted CD8+ T cells, which resulted in a striking reduction in the viral load [52]. This evidence concerns the gene CD4 and infection.