24: The Mechanism of Hepatitis D Superinfection

Session 24

We're joined by Dr. Karen Shackelford from BoardVitals as we talk about hepatitis and how antigens and antibodies appear and disappear during the course of infection.

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[02:20] Question of the Week

A 45-year-old male presents a sudden onset of flu-like symptoms and yellowing eyes which he thought looks scary to him when he saw his reflection on the mirror. His past medical history reveals positive Hepatitis B infection and his lab's elevated ALT and AST levels.

The consult suspects that he may not be superinfected with Hepatitis D. Hepatitis D virus can only propagate in the presence of Hepatitis B. The presence of which of the following components of Hepatitis B viral protein is necessary to allow Hepatitis D infection?

(A) HpX (pX antigen)

(B) Hepatitis B core antigen (HBcAg)

(C) Hepatitis B surface antigen

(D) Hepatitis B  e-antigen

(E) Hepatitis B virus DNA polymerase

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[03:35] Thought Process Behind the Correct Answer

The correct answer here is C. Remember the actual viral structures. Hepatitis D envelops single-stranded RNA virus. It can't make its own surface antigens. So it requires Hepatitis B surface antigen.

Hepatitis D can only be acquired either by co-infection or superinfection of an HPV carrier of co-infection. But this only resolves in 2% of the cases. HPV is a virulent pathogen. 

Superinfection results in chronic hepatitis in over 90% of cases. Often, hepatitis with rapid progression of cirrhosis in about 80% of cases.

But the influx of this type of viral infection has significantly declined since the development and widespread use of the Hepatitis B vaccine. However, this is still a problem in developing countries.

In a lot of underdeveloped countries, it's passed on through migrants from more developed countries. It's therefore important for people to be aware of their Hepatitis B immunity and their potential for this really virulent superinfection.

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[07:35] Understanding the Wrong Answer Choices

Hepatitis pX is pX protein of Hepatitis B virus. It's implicated in viral transcription, replication, and increased risk of hepatocellular carcinoma through the expression of this X protein gene.

The core antigen is the indicator of active viral replication. It's also a determinant of whether an individual is able to transmit the infection. But this is not the necessary component for the protein.

Hepatitis B e-antigen can act as a marker of our replication infectivity but this isn't the necessary component either.

Hepatitis B virus DNA polymerase is not necessary for HPV to replicate. HPV is the host hepatocyte, while the polymerase works to produce that complementary RNA.

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