[Role of programmed death-1 in viral infectious diseases]

The research on the immunoregulatory effect of programmed death-1 (PD-1) in infectious diseases mainly focuses on chronic viral infection, but there are few studies on acute viral infection. In chronic viral infection, PD-1 is highly expressed on the surface of CD8⁺ T cells, which is a sign of CD8⁺ T cell depletion. Recent studies have shown that in chronic viral infection, PD-1 is also highly expressed on the surface of regulatory T cells and binds to programmed death-ligand 1 (PD-L1) on the surface of exhausted CD8⁺ T cells, resulting in a stronger inhibitory effect on CD8⁺ T cell immunity. Blocking the PD-1/PD-L1 signaling pathway between exhausted CD8⁺ T cells and regulatory T cells can significantly reverse the depletion of CD8⁺ T cells and greatly improve the antiviral effect of CD8⁺ T cells. However, the role of the PD-1/PD-L1 signaling pathway in acute viral infection remains unknown. This article summarizes the latest research on PD-1 in infectious diseases and discusses its role in acute and chronic viral infection.