Effects of hepatitis B virus S protein on human sperm function

Hepatitis B virus (HBV) has been determined to exist in semen and male germ cells from patients with chronic HBV infection, but no data are yet available on the impact of HBV S protein (HBs), the main component of HBV envelop protein, on the human reproductive system. The purpose of this article was to investigate the effect of HBs on human sperm function. Sperm motility analyses, sperm penetration assays, mitochondrial membrane potential assays, immunolocalizations with confocal microscopy and flow cytometry analyses were performed. HBs reduced sperm motility in a dose- and time-dependent manner and caused the loss of sperm mitochondrial membrane potential. HBs-HBs monoclonal antibody (MAb) complex apparently aggravated such impairments. After 4 h incubation with HBs at concentrations of 25, 50, 100 mu g/ml, the percentages of sperm motility a+b significantly decreased compared with the control (P < 0.01). The fertilization rate and the fertilizing index in HBs-treated group were 40% and 0.57, respectively, which were significantly lower than 90% and 1.6, respectively, in the control (P < 0.01). The asialoglycoprotein receptor (ASGP-R) and HBs were found to localize mainly on the postacrosomal region. Both ASGP-R MAb and asialofoetuin, a high-affinity ligand of ASGP-R, inhibited the HBs-caused loss of sperm motility and mitochondrial membrane potential. HBs had adverse effects on human sperm function, and ASGP-R may play a role in the uptake of HBs into sperm cells, as demonstrated by the competitive inhibition of ASGP-R MAb or asialofoetuin, resulting in diminished impairment caused by HBs.