Correction: PD-1 Upregulated on Regulatory T Cells during Chronic Virus Infection Enhances the Suppression of CD8+ T Cell Immune Response via the Interaction with PD-L1 Expressed on CD8+ T Cells
J Immunol. 2015 Dec 15;195(12):5841-2.
doi: 10.4049/jimmunol.1502256.