Hepatitis B: Structure, Pathogenesis, and Diagnosis

By Ashma Shrestha •  Updated: 05/19/22 •  9 min read

A neonate develops yellowish eyes and skin after a month of life. When screened for hepatitis, the neonate is positive for hepatitis B infection, possibly by transmission from the mother. Hepatitis from the virus hepatitis B (HBV) is responsible for acute and chronic conditions in children and adults. The virus belongs to the family hepadnaviridae; hepa is related to liver cells and DNA because its genomic material is DNA.  

Structure of HBV

Structure of hepatitis B virus

Genomic arrangements

Genomic structure of HBV
Source: Abbas, Naaz & Arshad, Yousra & Shakoori, Abdul. (2006). Mutations in the hepatitis B virus core gene and its efficacy as a vaccine – A Review.. Proc. Pakistan Congr. Zool. 26. 103-129.

 

Pathogenesis of Hepatitis B

Virulence factors

Transmission of Hepatitis B

The transmission is generally in the following ways;

Incubation period

The incubation period of hepatitis B infection varies from a few weeks to 6 months.

NOTE:  When a patient tests positive for hepatitis for more than six months, the condition is chronic.

Replication

The replication of the hepatitis b virus has the following steps:

Clinical signs and symptoms

The clinical signs and symptoms of HBV depend on various factors like; age, immune system, and level of HBV in the body.

Acute HBV infection: Symptoms of HBV are as follows:

During the pre-icteric stage       

During the icteric phase

NOTE: Icteric- of, relating to, or affected with jaundice.

Chronic Hepatitis B infections: Most chronic hepatitis cases are asymptomatic, but if symptoms develop, it is similar to acute hepatitis and can be a sign of liver damage. It may lead to

Diagnosis of Hepatitis B

Sample collection and Transport

Blood serum is the desired sample to diagnose hepatitis B infection. For obtaining serum, Collect the blood in vials without anticoagulant. Allow the blood to clot and centrifuge to get the serum. Transport the sample as soon as possible.

Sample processing

  1. Direct microscopy 

Electron microscopy can detect the antigen-specific to HBV

  1.  Serodiagnosis

Hepatitis B panel tests are necessary for a definitive diagnosis of the infection. The panel includes three serological/immunological tests; detection of HBsAg, anti-HBs, and detection of anti-HBc.

  1. HBsAg: It is the surface antigen of hepatitis B. It is usually present in the serum of the patients during the incubation period and is detected during the acute phase. The presence of HBsAg even after six months indicates chronic infection. But the presence of this antigen alone is not the definitive diagnosis for chronic conditions.
  2. HBsAb/anti-HBs: The antibody is not detected during the acute phase. But is found during the chronic phase of the infection. It works in neutralizing the HBsAg by binding and forming an immune complex to a large number of HBsAg present in the blood.
  3. HBcAb/anti-HBc: It is the antibody against the core antigen of the hepatitis b virus. Both IgM and IgG are present as total antibodies. It persists for life and appears shortly after HBsAb. The presence of HBcAb does not differentiate between acute and chronic infection.  
  4. Other antigens: Detection of HBeAg and HBcAg, is done during the convalescent period of the infection using immunofluorescence techniques.
  1. Molecular Diagnosis

The genome and DNA polymerase activity is detectable during the incubation period of the infection. HBV PCR demonstration is helpful during the treatment of chronic stage and in diagnosing causes of liver failure.

  1. Other Tests

Liver function tests that help in determining abnormalities in the liver are also carried out to diagnose hepatitis. High levels of ALT and AST are found during the infection. Similarly, levels of serum bilirubin also indicate the intensity of jaundice. 

Treatment of Hepatitis B

No specific antiviral therapy is available to treat acute hepatitis B infection. Treatment of symptoms is the only measure in treating acute disease. The antiviral therapy is recommended for chronic cases. The treatment with interferons and nucleoside analogs is the standard method used. These do not cure HBV but only prevent morbidity and complications related to HBV infections. 

Interferon: Interferon-alpha is the most common interferon used in treating hepatitis. The interferon prevents the progression of acute infection to chronic and neutralization of viremia.

Nucleoside analogs: Nucleoside analogs such as lamivudine, adefovir, and telbivudine are widely used in antiviral therapy. These analogs halt the replication of HBV. These are bio-available and highly effective antiviral therapy available.

Prevention and Control

The preferable method to prevent and control HBV infections is both vaccines and immunoglobulins .

References

Ashma Shrestha

Hello, I am Ashma Shrestha. I am currently pursuing my Master's Degree in Microbiology. Passionate about writing and blogging. Key interest in virology and molecular biology

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6 responses to “MCQ on Hepatitis and Related Viruses”

  1. Asma says:

    I am not sure about all answers, but i tried to reach without any assistance (like a guess)
    1- retrovirus
    2- hepatitis A
    3- hepatitis D
    4- b
    5- d
    6- c
    7- d

  2. bidur says:

    Asma i appreciate your answers but for question no. 1, you fall prey to trap answer. The right answer is not retrovirus. for question number 2 and three you have given right answer and the rest of the answer is wrong,wish you give right answer to all the questions in next try.

  3. Asma says:

    then first i have to read about Hepatitis in detail

  4. zainab sajid says:

    i am just trying to findout my preparation…my answers are as follows..plz reply & tell me my mistakes.. 🙂
    1.(c)
    2.(d)
    3.(d)
    4.(c)
    5.(d)
    6.(c)
    7.(a)

  5. zainab sajid says:

    i really like this blos 🙂

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