Compared with that of the control group, the TIGIT expression of CD4+ and CD8+T cells among PBMCs of the infection group was significantly upregulated on the 7th day post infection (TIGIT+CD4+T cell: 5.58% ± 1.30% vs. 72.72% ± 0.64%, p < 0.001; TIGIT+CD8+T cells: 13.15% ± 2.32% vs. 78.72% ± 2.06%, p < 0.001). The gene discussed is CD8A; the disease is infection.