In addition, the combination of Tim-3 and its ligand galectin-9 can increase the expression level of the Tim-3 protein during the activation of regulatory T (Treg) cells, and the increase in Tim-3 level can induce helper T lymphocyte 1 (Th1) cell apoptosis and inhibit Th1-type immune response, thereby regulating Th1/Th2 balance in patients with hepatitis B (13, 16). This evidence concerns the gene HAVCR2 and hepatitis B virus infection.