Hepatitis B Virus – Part 1 – Hepatitis B Virus, HBV
- The best sample for the viral hepatitis B markers or profile is serum.
- A random sample can be taken.
Purpose of tests (Indications)
- Viral hepatitis B marker is done for:
- The diagnosis of HBV infection.
- The diagnosis of the carrier.
- The diagnosis of chronic hepatitis.
- Screening of blood for transfusion.
- HBV is also called serum hepatitis.
- Viral hepatitis B is caused by the DNA virus. This is a double-stranded DNA virus and one strand is incomplete.
- This virus belongs to the Hepadnaviridae family.
- 42 to 47 nm particles are infectious.
- 20 nm spherical and 20 nm by 1-micrometer particles are not infectious.
- The outcome of the disease is :
- Acute hepatitis.
- Chronic hepatitis.
- Liver cell carcinoma.
- This is usually seen in young adults.
- Transmitted by:
- Blood and blood products.
- It can spread by contaminated needles.
- It can spread through sexual contact.
- It can spread through other body fluids.
- There is transplacental spread.
- It is Common in (high-risk group):
- Multiple Blood transfusion recipients.
- Male homosexuals.
- Dialysis patients.
- Transplant patient.
- I/V drug user.
- Hospital worker because of needle pricks.
- Patient with leukemia and lymphoma.
- During delivery can infect the newborn if the mother is a carrier.
- A family member with close contact.
- Incubation period
- This has long incubation varying from 5 weeks to 6 months.
- This viral can give acute infection and may develop chronic disease.
- Structure of HBV
- This is a DNA virus and called a Dane particle.
- It has an inner core surrounded by an outer capsule.
- The outer capsule contains the antigen called the hepatitis B surface antigen (HBs-Antigen). This is also called as Australia antigen (HBsAg).
- The inner core contains HBV core antigen one is called HBc Ag and another antigen is incorporated into the Core antigen is called HBeAg.
- The HBcAg is a very small amount so not detectable but its Antibody is found in circulation.
There are three antigens:
There are three Antibodies:
Hepatitis B surface antigen (HBsAg)
- HBsAg appears first in the blood, so this is a more common test.
- HBsAg rises before the appearance of clinical signs and symptoms appear and is detectable.
- The peak is during the first week of symptoms.
- It returns to a normal level by the time jaundice subsides.
- If it persists then the patient will be a carrier or may develop chronic hepatitis.
Hepatitis B surface antibody (HBsAb)
- This antibody appears after roughly 4 weeks, after the disappearance of HBsAg.
- It indicates the end of the acute phase and the patient complete recovery from the infection.
- The patient will develop immunity to HBV infection.
- After vaccination, there is the appearance of HBsAb.
Hepatitis Core antigen (HBcAg)
- This is not detectable because of the very small quantity and it is incorporated with HBeAg.
Hepatitis B Core Antibody (HBcAb )
- This antibody appears after one month of infection.
- In acute infection, this will be HBcAb-IgM type and later replaced by HBcAb-IgG type.
- This antibody persists in circulation for several years.
- This antibody will be present in chronic hepatitis cases.
- In the window period when HBsAg is negative and still there are no HBsAb, then this is the antibody present in the patient.
- HbcAb-IgM is the marker in the window period in acute infections.
- This is also called as the window period marker.
Hepatitis Be antigen (HBeAg)
- HBeAg is a marker of the infectivity.
- HBeAg appears immediately after the appearance of HBsAg.
- HBeAg indicates early and acute disease.
- HBeAg positive in chronic hepatitis patients is a sign of a bad prognosis.
- The persistence of HBeAg indicates the development of chronic hepatitis.
Hepatitis B e antibody (HBeAb)
- The appearance of HBeAb is a sign of recovery.
- This antibody shows the end of the acute phase.
- There is variation in the symptoms from mild to severe.
- Most of the children and 50% of the adults are asymptomatic.
- The symptoms are insidious.
- The prodromal period often shows :
- The patient may have nausea and vomiting.
- There is weight loss.
- The acute period with jaundice lasts about one month.
- The patient will have jaundice and dark color urine.
- <1.5% may develop fulminant hepatitis.
- Chronicity decreases with age.
- 85% seen in the neonates.
- 25 to 50% of children.
- 6 to 10% of the adult.
- These patients are at high risk for liver cell carcinoma.
Table showing the difference between HAV and HBV:
|Mode of transmission||Parenteral||Feco-oral|
|Incubation period||60 to 160 days||15 to 40 days|
|Time of spread||All the year||Fall and winter|
|Chronicity||Roughly 5 to 10%||Complete recovery|
|Prophylaxis||γ-globulin protects||Some pools of γ-globulin|
The significance of various hepatitis markers:
- Acute infection
- HBsAg positive.
- HbcAb- IgM positive.
- Chronic infection
- 2 to 10 % develop chronic disease.
- HBsAg positive.
- HbcAb-IgG (Total) is positive.
- HBeAg positive indicate highly infective and poor prognosis.
- Recovery stage
- HBsAg is negative.
- HBsAb is positive.
- Window period marker
- HBsAg is negative.
- HBsAb is negative.
- HBcAb-IgM will be positive.
- For the HB viral load advice PCR.
- PCR qualitative for the HBV genome.
- PCR quantitative by HBV DNA by RNA probe.
Table showing various HBV antigens and antibodies
|HBsAg||4 to 12 weeks||1 to 3 months||Acute or chronic infection|
|HBeAg||1 to 3 weeks||6 to 8 weeks||Acute infection|
|HbSAb||3 to 10 months||6 to 10 years||Indicate immunity|
|HbeAb||4 to 6 weeks||4 to 6 years||End of acute infection|
|HbcAb IgM||2 to 12 weeks||3 to 6 months||Acute HBV infection|
|HbcAb total||3 to 12 weeks||Life long||Past HBV infection/recovery stage|
Table showing various stages of HBV infection:
- In the case of fulminant hepatitis, liver transplantation is needed.
- Treatment of chronic HBV infection is indicated when HBV-DNA >2000 IU/L and serum SGPT is raised.
- Antiviral medications are Lamivudine (Epivir), Adefovir (Hepsera), Telbivudine (Tyzeka) and Entecavir (Baraclude).
- Interferon alpha-2 is used mainly for young patients.
- Vaccination is the method of choice.
- This should be given at birth to infants born to carrier mothers.