The Hepatitis B Virus

The Hepatitis B Virus

Hepatitis B is a DNA Virus of the hepadnaviridae family of viruses. It replicates within infected liver cells (hepatocytes ). The infectious ("Dane") particle consists of an inner core plus an outer surface coat.

In real life the virus is a spherical particle with a diameter of 42nm (1nm = 0.000000001 meters) and is composed as follows. There is an outer shell (or envelope) composed of several proteins known collectively as HBs or surface Proteins.

This outer shell is frequently referred to as the surface coat. The outer surface coat surrounds an inner protein shell, composed of HBc protein. This inner shell is referred to as the core particle or cap Sid. Finally the core particle surrounds the viral DNA and the enzyme DNA Polymerase.
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How the virus reproduces

When the virus enters the body of a new host it's initial response, if it's gets past the immune system, is to infect a liver cell.
First the virus attaches to a liver cells membrane.






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The virus is then transported into the liver cell

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The core particle then releases it's contents of DNA and DNA polymerase into the liver cell nucleus.









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Once within the cell nucleus the hepatitis B DNA causes the liver cell to produce, via messenger RNA; surface (HBs) proteins, the core (HBc) protein, DNA polymerase, the HBe protein, HBx protein and possibly other as yet undetected proteins and enzymes. DNA polymerase causes the liver cell to make copies of hepatitis B DNA from messenger RNA.



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The cell then assembles 'live' copies of the virus. Via the above processes, versions of the hepatitis B virus are constructed by the liver cell .








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However because of the excess numbers of surface proteins produced many of these stick together to form small spheres and chains. These can give a characteristic "ground glass" appearance to blood samples seen under a microscope.






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The copies of the virus and excess surface antigen are released from the liver cell membrane into the blood stream and from there can infect other liver cells and thus replicate effectively.








What is Hepatitis:?

Hepatitis  A
 
Hepatitis B
 
Hepatitis C