Intracellular single-chain antibody against hepatitis B virus core proteininhibits the replication of hepatitis B virus in cultured cells

Hepatitis B virus (HBV) is one of the major causes of chronic liver disease s and hepatocellular carcinoma. In this study we used a single chain antibo dy (sFv), which is a man-made antibody with a strong affinity of immunoglob ulin, to inhibit HBV replication. Because HBV replication can only take pla ce in the viral nucleocapsid made of HBV core protein (HBc), we generated a nti-HBc sFv and examined whether intracellular anti-HBc sFv could inhibit v iral replication in the human hepatoblastoma-derived cell line that produce s HBV (HB611). With respect to HBV replication intermediates, both single-s tranded and partially double-stranded DNA intermediates were markedly suppr essed in the cells expressing anti-HBc sFv, although HBV RNA intermediates were not affected. This suggested that intracellular anti-HBc sFv inhibited HBV DNA replication by inhibiting reverse transcription from HBV pregenome RNA to single-stranded DNA, Because the sFv-HBc complex was detected in th e cells expressing anti-HBc sFv by immunoprecipitation analysis but the qua ntity of intracellular HBc was not affected, the anti-HBc sFv was suggested to inhibit HBV DNA replication by interfering with the function of HBc, Th ese results indicate that intracellular sFv against HBc might be effective as a novel active molecule for gene therapy of hepatitis B.