Abstract: BACKGROUND ＆ AIM: Hepatitis B is a public health problem of worldwide importance. To explore possibility of hepatitis B virus (HBV) vertically transmitting via spermatozoon, to study the replication and expression of sperm-mediated HBV genes in two-cell embryos of golden hamster. MATERIAL AND METHODS: Golden hamster oocytes were fertilized with spermatozoa cocultured with pBR322-HBV DNA plasmids. The slide preparation and RNA extraction of two-cell embryos were carried out. Fluorescence in situ hybridization (FISH), RT-PCR and immunofluoresence assay were performed to detect the replication and expression of sperm-mediated HBV genes in the embryonic cells. RESULTS: ① FISH HBV DNA-positive signals within each nucleus of two-cell embryo in the test sample were observed. ② RT-PCR the positive bands for HBx DNA in the tested samples were detected.③ Immunofluoresence assay the HBsAg-positive signals within cytoplasm of embryonic cells in the test sample were found. CONCLUSION: Sperm-mediated HBV genes are able to replicate themselves and express their function in early mouse embryo. It suggested that the vertical transmission of HBV via male germ cells from father to offspring could exist.

Key words: HBV gene, replication and expression, vertical transmission, golden hamster