Adhesion Molecules-28

Advances and Experimental-3

Aging-9

Agricultural Biotechnology-37

Angiogenesis-29

Antisense-4

Apoptosis-49

Atherosclerosis-12

Autoimmunity-69

Bacterial Virulence-18

Bioinformatics-13

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Biotechnology-100

Cancer Genetics-25

Cancer Metastasis-19

Cell Biology-16

Cell Cycle-34

Cell Metabolism-327

Channels and Transporters-79

Chaperones-11

Circadian Rhythms-13

Coagulation-14

Cytokines/Growth Factors-52

Development-223

DNA-56

DNA Surveillance and Repair-42

Drug Design-17

Endocrine-66

Evolution-33

Extracellular Matrix-30

Gastroenterology-52

Gene Expression-178

Gene Therapy-53

Heart-61

Heat Shock Proteins-19

Hematology-11

Immunology-93

Infectious Disease-71

Ischemia-Reperfusion-33

Leptin and Leptin Antagonists-1

Medical-22

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Nucleus-15

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Protein-12

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RNA-152

Signal Transduction-186

Stem Cells-80

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T-Cell Activation-12

Tissue Engineering-116

Transplant-51

Vaccines-82

Viruses-85

Chapter category: Viruses

Hepatitis Delta Antigen: Biochemical Properties and Functional Roles in HDV Replication

Chapter authors:
Michael M.C. Lai

Hepatitis delta antigen (HDAg) was first detected in the nucleus of the hepatocytes of some patients infected with hepatitis B virus (HBV).68 The presence of HDAg was frequently associated with severe hepatitis. This antigen was initially thought to be a previously unrecognized HBV-encoded antigen, but later was found to be associated with a novel virus, hepatitis delta virus (HDV).69 HDAg is an internal component of the HDV virion particles, and, together with the viral RNA genome, forms viral nucleocapsid.2 There are approximately 70 HDAg molecules per RNA molecule in each virion particle,72 but the precise structure of the nucleocapsid has not been determined. HDAg in virus preparations from most of the patients usually consists of two distinct forms of different size (27 and 24 kDa, termed the large and the small HDAg, L- and S-HDAg, respectively). The nucleocapsid is released from the virus particle after the latter is treated with nonionic detergents.72 Besides this structural role, HDAg also plays a very critical role in the HDV life cycle by participating in various steps of viral replication, including viral RNA synthesis (by S-HDAg), virus assembly (by L-HDAg) and others. HDAg is the only known functional protein encoded by HDV RNA. It is encoded by the antigenomic-sense strand of HDV RNA, but is translated from a 0.8-kb mRNA, which is transcribed from the viral genomic RNA.

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