The Hepatitis B virus
Hepatitis B is what we used to originally known as just simply
serum hepatitis. Hep B has been recognized as this new name
since World War II. The virus is responsible for current
epidemics in parts of Asia and Africa. Recognized as endemic in
China and various other parts of Asia, the Hepatitis B virus has
infected over one third of the world's current population.
Hepatitis B is in the Hepadnavirus family. Meaning that it
consists of a proteinaceous core particle that has the viral
genome inside of it in the form of double stranded DNA. It also
has an outside lipid-based envelope that contains embedded
proteins. These envelope proteins on the outside are involved in
viral binding and release into susceptible cells. Where as the
inner capsid refinds the DNA genome to a cell's nucleus where it
transcribes viral mRNAs. Although HIV, the virus that causes
AIDS, and Hepatitus are not related they are both viruses that
use reverse transcription process. This also include HTLV.
Hepatitis B's genome is DNA, and reverse transcription is one of
the latter steps of the entire process which results in making
new viral particles. HIV on the other hand has an RNA genome and
reverse transcription is one of the first steps in replication
of the virus.
Hepatitis B is most commonly transmitted through direct exposure
to bodily fluids that contain the virus. This is a wide category
but in most cases includes: - Re-using contaminated needles and
syringes - Uncleanly Blood transfusions - Unprotected sexual
contact - Direct transmission from mother to child during
childbirth
The dominant mode of transmission depends largely on the
prevalence of the disease in a given area. For example if areas
such as North America drug abuse and unprotected sex are the
primary mode of infection. Where as in areas such as such as
China where Hepatitis B is very prevalent, the vertical
transmission(mother to child) is the most common. A mother who
is positive for the Hepatitis B surface virus has a 20% risk of
passing the infection to her offspring during birth. That
percentage can rise to as high as 90% if the mother is also
infected with the hepatitis B e antigen.
The older a person is at the time of infection, the greater the
risk that their body will not clear the infection. Hepatitis B
infection can lead to a permanent inflammation of the liver, the
result of this inflammation leads cirrhosis. These affects
largely increase the likelyhood of developing liver cancer.