Hepadnaviruses including Hepatitus A, B and C

Hepadnaviridae is a family of hepadnaviruses comprised by 2 genera: Avihepadnavirus and the Orthohepadnavirus. Hepadnaviruses have partially double strands DNA (partial dsDNA virion) and they replicate their genome in the host cells using reverse transcriptase and are therefore, termed retroviruses. Their virion DNA, invades the hepatocytes (i.e., the liver cells) of vertebrates, which are their natural hosts. When hepadna retroviruses invade a cell, a complete viral dsDNA is made before its random integration in one of the host's chromosomes, and is then transcribed into an intermediate messenger RNA (mRNA) into the hosts' cells

The viral mRNA then leaves the nucleus and undergoes reverse transcriptase, mediated by a viral reverse transcriptase enzyme that transcribes complementary strands of complementary dsDNA in the cell cytosol, thus forming new partial dsDNA virions.

Orthohepadnavirus is the pathogenic agent that causes chronic hepatitis (thta is, Hepatitis type B) in mammals, which may eventually lead to either cirrhosis or liver cancer if not detected and treated. Hepatitis B Virus or HBV, the prototype member of the family Hepadnaviridae, is transmitted by both infected blood (blood transfusions, grafts) and by body fluids (usually through sexual relations with infected partners). HBV comprises several viral species that also infect the liver cells of orangutans, dogs, and other mammalians besides, of course man. Vaccines for both human Hepatitis B and several forms of animal Hepatitis B (lions, cats, dogs) are available as a standard form of disease prevention. All Hepadnaviridae viruses have a high affinity with liver cells (hepatotropy) and the viruses of the genus Avihepadnavirus, also known as avian hepadnaviruses, have as targets the liver of birds, such as storks, ducks and herons

Hepatitis simply means inflammation of the liver. Viral hepatitis is liver inflammation caused by a virus. There are several types of viral hepatitis, including hepatitis A, B, C, D, E, and G.

Hepatitis A

The hepatitis A virus is the organism responsible for this disease that bears its name. It belongs to the Picornaviridae family and can also live outside the body for a few months, if conditions permit. Following transmission of the hepatitis A virus, a person does not immediately become sick. Symptoms typically appear 15 to 45 days after the infection.

The hepatitis A virus (HAV) is the virus responsible for hepatitis A. A person infected with the virus may then develop:
• A sudden onset of fever
• Extreme tiredness
• Nausea
• Lack of appetite
• Abdominal pain (stomach pain)
• Yellowing of the skin or whites of the eyes (known as jaundice).

These symptoms occur because the virus directly affects the liver. However, not everyone infected with the hepatitis A virus will develop symptoms.

The virus is an RNA virus that belongs to the genus hepatovirus of the Picornaviridae family. It can live outside the body for a few months, depending on environmental conditions The virus can be killed by boiling water for one minute, contact with formaldehyde or chlorine, or with ultraviolet radiation.

Hepatitis B

Hepatitis B is one of several types of hepatitis (liver inflammation). Many acute cases of hepatitis B get better on their own, but chronic hepatitis B many times requires treatment with medications. Among the ways in which the hepatitis B virus can be spread are contact with infected blood or sex with an infected person. The hepatitis B virus can also be transmitted from an infected mother to her child during childbirth. The best way to prevent hepatitis B is through the standard hepatitis B vaccine.

Hepatitis B is a disease of the liver caused by a virus (specifically, the hepatitis B virus). Most people who get hepatitis B can get rid of the virus on their own, but others can develop chronic (or life-long) hepatitis B. The cause of hepatitis B is an infection with the hepatitis B virus itself. The hepatitis B virus is a DNA virus that belongs to the genus Orthohepadnavirus of the Hepadnaviridae family. There are two types of hepatitis B - acute (recently acquired) and chronic (life-long).

For most people with acute hepatitis B, symptoms gradually get better within a couple of months itself. These people with have no long-lasting liver damage and will recover completely. For some people, the body is not able to completely get rid of the virus. These people end up having a long-term liver infection. This is called chronic hepatitis B. People with chronic hepatitis B can infect others and are at an increased risk of serious liver disease, including cirrhosis and liver cancer.

Besides hepatitis B, there are several other types of viral hepatitis, including hepatitis A, C, D, E, and G.

Hepatitis C

Hepatitis C is a disease that causes direct inflammation of the liver. Approximately 300 million people world wide are infected with the hepatitis C virus. Based on current hepatitis C statistics, it's estimated that almost 8,000 to 10,000 people die each year from chronic liver disease caused by hepatitis C!

What Causes Hepatitis C?
Hepatitis C is caused by infection with the hepatitis C virus (HCV). The virus is able to enter liver cells from the blood and then use those cells to directly make more copies of itself. During this process, liver cells are damaged, leading to inflammation and possibly scarring of the liver.

How Is Hepatitis C Spread?
Hepatitis C is spread most frequently when a person comes in contact with infected blood. This can happen by working in a dialysis unit or by sharing needles for tattoos, body piercings, or drugs. Toothbrushes, razors, or manicure tools can harbor small amounts of infected blood. While hepatitis C transmission can occur through sexual intercourse, this is quite rare.

It is not currently believed that oral sex can also spread hepatitis C. Also, you cannot get hepatitis C from a kiss, or from other everyday activities like shaking hands or hugging.

Possible Symptoms of Hepatitis C
Approximately 80% of people with hepatitis C have no symptoms whatsoever, even after many years. Most patients do not develop symptoms until there is already cirrhosis, or even liver failure.