Molecular Components of Hepatitis B Virus

Since the discovery of Australia antigen and its association with type B hepatitis, molecular characterization of the components making up hepatitis B virus (RBV) have been pursued with worldwide interest. Over the past two decades, such characterization has led to the development of sensitive assays to screen and exclude contaminated units from blood banks and has recently resulted in the licensing of several RBV vaccines. That more than 200 million people worldwide are chronically infected with RBV, and that they are at a high risk for the development of chronic hepatitis and hepatocellular carcinoma, still represent formidable problems in our understanding of host-virus relationships on the molecular level. In the absence of a suitable tissue culture system, and with a very limited host range of infection, characterization of RBV on the molecular level has made remarkable progress recently with the advent of genome cloning, sequencing and expression of individual virus genes by recombinant DNA technology. The presence of hepatitis B-like viruses in an expanding number of animal hosts, and the possibility of virus replication in cells other than hepatocytes, provide great promise that future work will elucidate the molecular mechanisms operative in the various outcomes of RBV infection.

Contenu

Hepatitis B Surface Antigen (HBsAg).- Nature of the "a" determinant.- Antigenic and immunogenic properties of HBsAg associated components.- Host components in HBsAg particles.- Possible vaccines lacking host components.- HBsAg associated carbohydrate.- HBsAg and the receptor for polymerized albumin.- Dane Particle "Specific" Antigenic Determinants.- Anti-HBs Monoclonal Antibodies.- Dane Particles and Hepatitis B Core Antigen (HBcAg).- Anti-HBc.- Hepatitis B e Antigen.- HBeAg and infectivity.- Chemical characterization.- HBeAg activity in Dane and core particles.- The Protein Kinase Activity in HBcAg and the Proposed Nucleic Acid Binding Properties of Core Polypeptide.- The DNA Polymerase Activity of HBV.- Characterization and relation to other polymerases.- Chemotherapy.- HBV Genome Structure and Expression.- General physical characteristics.- Restriction endonuclease analysis.- Genome isomers.- HBV in Hepatocellular Carcinoma and the Chronic Carrier State.- HBV DNA in human hepatoma cell lines.- HBV DNA in tumorous and nontumorous tissues.- Karyotyping of human hepatoma cells.- Nucleic Acid Sequencing of Dane Particle DNA and Expression of HBV Genes.- Nature of open reading frames.- Surface antigen gene structure and expression.- Core antigen and e antigen gene structure and expression.- The proposed polymerase gene of HBV DNA.- Open region X in HBV DNA.- The 5? Terminal Protein and Possible Origin of Genome Replication Associated with Hepatitis Viruses.- Replication Scheme for Hepatitis B and Related Viruses.- Conclusions.- References.