There are 4 open reading frames derived from the same strand (the incomplete + strand)
S - the 3 polypeptides of the surface antigen ( preS1, preS2 and S - produced from alternative translation start sites.
C - the core protein
P - the polymerase
X - a transactivator of viral transcription (and cellular genes?). HBx is conserved in all mammalian (but not avian) hepadnaviruses. Though not essential in transfected cells, it is required for infection in vivo.
Hemophiliacs and other patients requiting blood and blood product treatments
Health care personnel who have contact with blood
Residents and staff members of institutions for the mentally retarded
Symptomatic Infection Chronic Infection Age at Infection Chronic Infection (%) Symptomatic Infection (%) Birth 1-6 months 7-12 months 1-4 years Older Children and Adults 0 20 40 60 80 100 100 80 60 40 20 0 Outcome of Hepatitis B Virus Infection by Age at Infection Chronic Infection (%)
Premature mortality from chronic liver disease: 15%-25%
Possible Outcomes of HBV Infection Acute hepatitis B infection Chronic HBV infection 3-5% of adult-acquired infections 95% of infant-acquired infections Cirrhosis Chronic hepatitis 12-25% in 5 years Liver failure Hepatocellular carcinoma Liver transplant 6-15% in 5 years 20-23% in 5 years Death Death
Symptoms HBeAg anti-HBe Total anti-HBc IgM anti-HBc anti-HBs HBsAg 0 4 8 12 16 20 24 28 32 36 52 100 Acute Hepatitis B Virus Infection with Recovery Typical Serologic Course Weeks after Exposure Titre
Acute HBV Infection with Progression to Chronic Infection: Typical Serologic Course IgM anti-HBc Total anti-HBc HBsAg Acute (6 months) HBeAg Chronic (Years) Anti-HBe 0 4 8 12 16 20 24 28 32 36 52 Years Weeks after Exposure Titer
Following transmission of HBV from mother to infant, which of the following is the most common medical problem for the infant?
A. Liver failure.
B. Chronic HBV carrier state
C. Development of lymphoma.
D. Opportunistic infections.
E. Development of CNS disease.
Why are the Chinese at greater risk than Westerners?
Because there are more Asian people already infected with hepatitis B than Westerners. Although hepatitis B is not an "Asian disease", it affects hundreds of millions of Asians. Since the Asian community starts with such a large number of infected people, there are more people who can pass the hepatitis B virus on to others. This increases the risk that you could get infected. Since there is a smaller number of Westerners who are infected, this group has a lower risk of infection
How is hepatitis B spread differently among the Chinese?
Asians and Westerners can both get hepatitis B through contact with blood, unprotected sex, shared needles, and from an infected mother to newborn baby during delivery.
Jobs and lifestyle choices can create an equal risk for both groups. However, hepatitis B is often spread differently among Asians.
Asians are most commonly infected as newborns - from a mother who unknowingly passes the virus on during delivery.
Young children are also at risk if they live in close daily contact with an infected family member.
Babies and children are more likely to develop a chronic hepatitis B infection because their young immune systems have trouble getting rid of the virus.
Westerners are most commonly infected as young adults through unprotected sex. As adults, their immune systems can usually get rid of the virus and they "recover" from an infection.
What does it mean to be a "chronic carrier" of hepatitis B?
People who are unable to get rid of the hepatitis B virus are diagnosed as being a "chronic carrier".
The virus can stay in their blood and liver for a long time.
They can unknowingly pass the virus on to other people.
Chronic hepatitis B can also lead to serious liver diseases, such as cirrhosis or liver cancer. Not every chronic carrier will develop serious liver disease.
However, they have a greater chance than someone who is not infected.
Why should Chinese people be worried about chronic hepatitis B infections?
Because chronic hepatitis B can lead to cirrhosis or liver cancer.
It's important to get tested because early diagnosis can lead to early treatment which can save your life.
Also, chronic carriers can spread the virus to others. Since most chronic carriers don't know they are infected, they are unknowingly spreading it to many other people.
If people are not tested, hepatitis B can pass through several generations in one family and throughout the community.