Expression analysis of bovine PD-1 in BLV-infected cattle. (a, b) Percentages of PD-1-expressing CD4+ and CD8+ T cells in PBMC (a) and LN (b) isolated from BLV- cattle (CD4+ T cells; n = 20 and 31, CD8+ T cells; n = 16 and 31), BLV+ cattle (CD4+ T cells; n = 35 and 15, CD8+ T cells; n = 28 and 15) and BCBL (CD4+ T cells; n = 7 and 6, CD8+ T cells; n = 7 and 6). (c) An example of gating strategies for PD-1 expression in CD4+ T cells and CD8+ T cells isolated from lymph node of BCBL and BLV- cattle. Values in the quadrant indicate the percentage of the cells in lymphocytes other than IgM+ B cells. (d) Percentages of PD-L1-expressing gp51+ (n = 5) and gp51- (n = 5) in IgM+ B cells from BLV+ and BLV- cattle (n = 9). Representative dot plots of PD-L1 staining in gp51+ or gp51- B cells are also shown. Statistical comparisons were made using one-way ANOVA with Tukey’s test. Differences were considered statistically significant at P < 0.05 (** P < 0.01).