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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.

Please also check out Specialty Stories, a podcast dedicated to helping you figure out what specialty you want to practice. Listen to different physicians as I interview them about why they chose their specialty, what they like and don’t like about it, and much more.

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Listen to this podcast episode with the player above, or keep reading for the highlights and takeaway points.

[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

[Related episode: What Does Academic Infectious Disease Look Like?]

[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.

[Related episode: USMLE and COMLEX Prep: Tropical Medicine—Dengue Fever]

[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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