The pathogenesis of both acute and viral hepatitis is slowly being unravelled. Thus far, most data show that members of the hepadnaviridae family are not highly cytotoxic per se. It appears that the intense levels of cellular death are primarily due to host defence mechanisms against the HBV infection.

The virus is most efficiently transmitted through percutaneous introduction. Sexual transmission and perinatal transmission are less efficient, typically requiring high titres of virus. HBV is most concentrated in the liver and blood, with lesser amounts found in saliva and semen.

The Liver
The liver plays a pivotal role in helping the body maintain adequate levels of metabolites in the blood stream. The liver is also important in detoxifying potentially toxic chemicals that may enter our blood stream.

Torso Anatomy (human male)

On average, the liver weighs about four pounds and is the only organ able to regenerate itself even when up to 25% of it is removed.

The liver has many functions involved in digestion and metabolite conversion. Some of its key functions are:

Bile Production:This fluid is stored in the gallbladder for release when needed in digestion. Bile is necessary for the digestion of fats as it dissolves fat down into small globules. Bile works in the same way as detergent lifts oil off greasy plates. Bile also assists in the absorption of fat soluble vitamins (i.e. vitamin A, D, F, and K) In addition, bile converts beta-carotene to vitamin A.
Glucose Homeostasis: Blood sugar levels must be maintained for other organs to functions properly, especially the brain. The liver plays a pivotal role in that it is one of the sites where excess sugar can be stored in the form of glycogen (a polysaccharide) when there is an overabundance. Glucose can then be released from the glycogen when needed by the body.
Fat Metabolism: The liver is involved in the synthesis of fatty acids from amino acids and sugars, in the production of lipoproteins, cholesterol, and phospholipids, and in the oxidation of fat to produce energy. Excess food is converted to fat in the liver which is then transported to the adipose (fatty) tissues of the body for longer-term storage.
Detoxification: Protein metabolism and bacterial fermentation of food in the intestines produce the by-product ammonia which is detoxified by the liver. The liver regulates protein metabolism. The liver also combines toxic substances including metabolic waste, insecticide residues, drugs, alcohol, and chemicals with other substances that are less toxic. These substances are then excreted from the kidneys. Thus, to have proper liver function, you must have proper kidney function. When either the liver or the kidney appears to be malfunctioning, treating both organs produces the best health results.

Cell/Tissue Tropism
The primary site of HBV replication is, without surprise, the liver. However, various extrahepatic sites have been proposed. Hemapoetic stem cells have been postulated to support viral replication. This could account for various hematological abnormalities sometimes found in patients with acute hepatitis.

HBV replicative intermediates and/or viral transcripts have also been found in extrahepatic sites. These include mononuclear cells, bile duct epithelial, endothelial, pancreatic acinar cells, and smooth muscle tissue. They have also been found in adrenal glands, gonads, cultured bone marrow, kidneys, lymph nodes, spleen, and thyroid glands of acute hepatitis B infected patients.


Elfassi, E., Romet-Lemmone, J.L., Essex, M., Frances-McLane, M. and Haseltine, W.A. 1984. Evidence of Extrachromosomal Forms of Hepatitis B Viral DNA in Bone Marrow Culture Obtained from a Patient Recently Infected with Hepatitis B Virus. Proc Natl Acad Sci USA; 81: 3526-3528.

Hadchouel M., Pasquinelli, C., Fournier, J.G., et al. 1988. Detection of Mononuclear Cells Expressing Hepatitis B Virus in Peripheral Blood from HBsAg Positive and Negative Patients by in situ Hybridization. J. Med. Virol.; 24: 27-32.

Laure, F., Zagury, D., Saimot, A.G., Gallo, R.C., Hahn, B.H. and Brechot, C. 1985. Hepatitis B Virus DNA Sequences in Lymphoid Cells from Patients with AIDS and AIDS-related Complex. Science; 229: 561-563.

Lie-Injo, L.E., Balasegaram, M., Lopez, C.G. and Herrera, A.R. 1983. Hepatitis B Virus DNA in Liver and White Blood Cells of Patients with Hepatoma. DNA; 2: 301-308.

Noonan, C.A., Yoffe, B., Mansell, P.W.A., Melnick, J.L. and Hollinger, F.B. 1986. Extrachromosomal Sequences of Hepatitis B Virus DNA in Peripheral Blood Mononuclear Cells of Acquired Immune Deficiency Syndrome Patients. Proc Natl Acad Sci USA; 83: 5698-5702.

Romet-Lemonne, J.L., McLane, M.F., Elfassi, E., Haseltine, W.A., Azocar, J. and Essex, M. 1983. Hepatitis B Virus Infection in Cultured Human Lymphoblastoid Cells. Science; 221: 667-669.

Shen, H.D., Choo, K.B., Lee, S.D., Tsai, Y.T. and Han, S.H. 1986. Hepatitis B Virus DNA in Leukocytes of Patients with Hepatitis B Virus-Associated Liver Disease. J Med Virol; 18: 201-211.

Yoffe, B., Noonan, C.A., Melnick, J.L. and Hollinger, F.B. 1986. Hepatitis B Virus DNA in Mononuclear Cells and Analysis of Cell Subsets for the Presence of Replicative Intermediates of Viral DNA. J Infect Dis; 153: 471-477.

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