[Structure of hepatitis B virus and its related serological markers]

Hepatitis B virus (HBV) is a small DNA virus belonging to hepadnaviridae. Genomic DNA of HBV has four open reading frames representing the S gene with pre-S1 and pre-S2 regions for envelope protein, the C gene coding for a nucleocapsid protein, the P gene for the putative DNA polymerase, and the X gene encoding a protein with transcriptional transactivating function. The C gene is preceded in phase by the precore region. Recently, this region has been attracting attention because of its role in the synthesis and secretion of HBe Ag. It has been postulated that HBV mutants with precore region defects prevail in persistently infected hosts along with seroconversion to anti-HBe. Recent advances in molecular biology have enabled us to detect minute amounts of HBV DNA by means of polymerase chain reaction (PCR) and to analyze gene function in detail. The advanced techniques and conventional serological assay systems will help in clarifying the pathogenesis of acute and chronic hepatitis B, in preventing and eradicating HBV infection.