Abstract Background Controversy exists regarding the role of PD1 and its ligand PD-L1 in chronic hepatitis B infection. In some studies. persistent HBV infection has been attributed to high levels of PD-1 and PD-L1 expression on HBV-specific T-cells and antigen-presenting cells (APCs) respectively. Other studies revealed that the up-regulation of PD-1 and PD-L1 during an acute inflamm... https://lockdownsecuritycanada.shop/product-category/travel-fee/