The presence and expression of the hepatitis B virus in human oocytes and embryos

BACKGROUND: The objective of this study was to explore the potential for vertical transmission of hepatitis B virus (HBV) from parents to offspring via human germ cells. METHODS: For study samples, 250 oocytes from hepatitis B surface antigen (HBsAg) seropositive women and 578 embryos from couples with at least one HBsAg seropositive partner were collected. HBV DNA in the nuclei of oocytes and embryos was detected by fluorescence in situ hybridization; HBsAg expression was analysed using immunofluorescence; and serum HBV DNA levels were measured by real-time PCR. The HBV infection duration of the women and the serum HBsAg status of their mothers were also examined. RESULTS: HBV DNA was present in 9.6% (24/250) of oocytes and 14.4% (83/578) of embryos. Rates of HBV DNA positive embryos were similar among couples in which the woman, man or both partners were HBsAg seropositive, 13.1% (57/436), 21.3% (16/75) and 14.9% (10/67), respectively. Rates of positivity in oocytes and embryos were significantly higher in a group with high serum levels HBV DNA than in a group with lower serum levels (P = 0.004 and P = 0.002, respectively). Higher rates of oocyte positivity were found for women whose mothers were HBV infected compared with those with uninfected mothers. Expression of HBsAg was observed in 8.7% (2/28) oocytes and 14.1% (10/71) embryos (P = 0.34). CONCLUSIONS: The presence of HBV DNA in human oocytes or embryos was related to the women's serum levels of HBV DNA and the infection status of their mothers. The HBV positive embryos were either maternally or paternally dependent. HBV infection may result in vertical transmission to the offspring via germ cells.