The magnesium transporter 1 (MAGT1) is a critical regulator of basal 
intracellular free magnesium ([Mg2+]i) levels. It has been shown that MAGT1 was 
involved in the disorder in Mg2+ homeostasis after Epstein-Barr virus (EBV) 
infection. Here, we identified the effects of MAGT1-mediated disturbance of Mg2+ 
homeostasis on chronic hepatitis B virus (HBV)-infected natural killer (NK) and 
CD8+ T cells. The expression of MAGT1 was gradually decreased with the increase 
of infected time in CD8+ T cells, but not with that in NK cells, of the 
patients. Decreased level of intracellular free Mg2+ ([Mg2+]i) leads to 
defective expression of programmed cell death 1 (PD-1) and the NK activating 
receptor (NKG2D) in NK and CD8+ T cells. Our data illustrate that [Mg2+]i plays 
a key role in control of HBV infection.