Effects of hepatitis B virus S protein exposure on sperm membrane integrity and functions.

BACKGROUND: Hepatitis B is a public health problem worldwide. Viral infection can affect a man's fertility, but only scant information about the influence of hepatitis B virus (HBV) infection on sperm quality is available. The purpose of this study was to investigate the effect of hepatitis B virus S protein (HBs) on human sperm membrane integrity and functions. METHODS/PRINCIPAL FINDINGS: Reactive oxygen species (ROS), lipid peroxidation (LP), total antioxidant capacity (TAC) and phosphatidylserine (PS) externalization were determined. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays and flow cytometric analyses were performed. (1) After 3 h incubation with 25 µg/ml of HBs, the average rates of ROS positive cells, annexin V-positive/propidium iodide (PI)-negative cells, Caspases-3,-8,-9 positive cells and TUNEL-positive cells were significantly increased in the test groups as compared to those in the control groups, while TAC level was decreased when compared with the control. The level of malondialdehyde (MDA) in the sperm cells exposed to 50 µg/ml of HBs for 3 h was significantly higher than that in the control (P<0.05-0.01). (2) HBs increased the MDA levels and the numbers of ROS positive cells, annexin V-positive/PI-negative cells, caspases-3, -8, -9 positive cells and TUNEL-positive cells in a dose-dependent manner. (3) HBs monoclonal antibody (MAb) and N-Acetylcysteine (NAC) reduced the number of ROS-positive sperm cells. (4) HBs decreased the TAC levels in sperm cells in a dose-dependent manner. CONCLUSION: HBs exposure could lead to ROS generation, lipid peroxidation, TAC reduction, PS externalization, activation of caspases, and DNA fragmentation, resulting in increased apoptosis of sperm cells and loss of sperm membrane integrity and causing sperm dysfunctions.