Objective    To investigate the possibility and regulation of that hepatitis B virus (HBV) infects trophoblastic cells in primary culture.     Methods    Trypsin and DNAse sequential digestion and Percoll density centrifugation were used to separate and purify human chorionic trophoblastic cells. The direct serum (HBV DNA positive) infection method was adopted to infect trophoblastic cells. The results of HBV infection of trophoblastic cells were compared with that of normal human adult liver cell line L02 and that of liver cancer cell line HepG2.2.15. Real-time PCR was used to detect HBV DNA in culture supernatant. Further

ultrastructural characteristics of infected trophoblastic cells were observed with transmission electron microscope.     Results    The HBV DNA in culture supernatant that released by HBV infected trophoblastic cells reached the peak in 48-72 h. For L02 cell

it occurred in 12-24 h and for HepG2.2.15 cell line

it kept increasing. The ultrastructure of infected HBV trophoblastic cells differed obviously from that of normal cells

and showed hyperplasia of lysosome

appearance of vacuoles and virus-like particles around the nucleus.      Conclusion    Trophoblastic cells could be infected by HBV

and the cellular ultrastructure changed dramatically following HBV infection.