INTRODUCTION & HISTORY
The following pages attempt to provide accurate and comprehensible information regarding the various aspects of the hepatitis B virus. Granted, some parts of this site require some scientific background to fully comprehend (i.e. the structural and molecular biology pages), but I have also included a question and answer page for those who feel some information needs clarification. May you find the information you are looking for within.
B Virus General Information
of the Hepatitis B Virus
Before the viruses causing hepatitis were isolated, transmission was differentiated on the basis of epidemiological observations. Type A hepatitis was considered predominantly transmitted via the fecal-oral route while type B hepatitis was believed to be primarily transmitted parenterally.
In 1963, when searching for polymorphic serum proteins, Blumberg discovered a previously unknown protein in the blood of an Australian aborigine. (3) This protein was denoted as the Australia (Au) antigen. It became apparent that this protein was related to type B hepatitis. By 1968, other investigators, notably Prince, Okochi, and Murakami, had established that the Au antigen (now known as the hepatitis B surface antigen) was only found in the serum of type B hepatitis infected patients. (4), (5)
In 1973, Dane found virus-like particles in the serum of patients suffering from type B hepatitis. (6) These particles were designated as the hepatitis B virus (HBV). Non-related hepatitis viruses were discovered later, but the hepatitis B virus retained its name.
Kaplan confirmed the viral nature of these particles by detecting an endogenous DNA-dependent DNA polymerase within its core. (7) Discovery of this polymerase allowed Robinson to detect and characterize the HBV genome. (8) The HBV genome is unique in the world of viruses due to its compact nature, use of overlapping reading frames, and dependence on a reverse-transcriptional step, though the virion contains primarily DNA. In light of this, the human hepatitis B virus became the archetype of the hepadnavirus family, Hepadnaviridae.
Though the hepatitis B surface antigen (HBsAg) from HBV has been detected in other primates, humans remain its primary reservoir. In the recent past, many related viruses have been found in other species, but each particular virus is species specific. With human HBV as the archetype, the members of the hepadnaviridae family include duck hepatitis B virus (DHBV), ground squirrel hepatitis virus (GSHV), snow goose hepatitis B virus (sgHBV), woodchuck hepatitis virus (WHV), and wooley monkey hepatitis virus. There are likely other viruses that have yet to be isolated which would also be classified as a hepadnaviridae.
HBV has been estimated by the World Health Organization (WHO) to have infected over two billion people worldwide. Approximately 500 million are chronic carriers. Transmission of HBV is primarily through blood and/or sexual contact, though other methods of transmission have been suggested. The large reservoir of infected individuals has sustained a satellite virus known as the hepatitis D virus (HDV). HDV can only replicate in cells already infected with HBV since HDV uses hepatitis B surface proteins to package its own RNA. However, the nature of HDV is quite different from HBV. Therefore, it will only be mentioned briefly in this website.
1. MacCallum, F. O. 1947. Homologous Serum Jaundice. Lancet; 2: 691-692.
2. World Health Organization. 1973. Viral Hepatitis Reposty of WHO Scientific Group. WHO Technical Report Series 512. Geneva: WHO.
3. Blumberg, B.S., Gerstley, B.S.J., Hungerford, D.A., London, W.T., and Sutnick, A.J. 1967 A Serum Antigen (Australia Antigen) in Down's Syndrome, Leukemia and Hepatitis. Annals of Internal Medicine; 66: 924-931.
4. Prince, A.M. 1968. An Antigen Detected in the Blood During the Incubation Period of Serum Hepatitis. Proc. Natl Acad Sci USA; 60: 814-821.
5. Okochi K. and Murakami, S. 1968. Observations on Australia Antigen in Japanese. Vox Sang; 15: 374-385.
6. Dane, D.S., Cameron, C.H. and Briggs, M. 1970. Virus-like Particles in Serum of Patients with Australia-Antigen-Associated Hepatitis. Lancet; i: 695-698.
7. Kaplan, P.M., Greenman, R.L., Gerin, J.L., Purcell, R.H. and Robinson,W.S. 1973. DNA Polymerase Associated with Human Hepatitis B Antigen. Journal or Virology; 12: 995-1005.
8. Robinson, W.S. and Greenman, R.L. 1974a. DNA Polymerase in the Core of the Human Hepatitis B Virus Candidate. Journal of Virology; 13: 1231-1236.
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