Level of CD4⁺ and CD8⁺ cell apoptosis in PBMCs after EBV stimulation. PBMCs were stimulated with purified Akata virus or mock virus and were then seeded at 5 × 10⁵ cells/mL and cultured for 24 hours. Cells were subsequently stained with FITC-coupled Annexin V and PE-labeled anti-CD4 or PE-labeled anti-CD8. The mean percentage values of Annexin V-positive CD4⁺ or CD8⁺ cells ± SEM obtained from 4 separate donors are plotted.