Which one of the following is a DNA virus?

Appeared in: NHM UP Staff Nurse - 2017

Explanation

Hepatitis B virus (HBV) is the only virus among the options that has a DNA genome.
HBV belongs to the Hepadnaviridae family and possesses a unique, partially double-stranded circular DNA.
Unlike typical DNA viruses, HBV replicates via an RNA intermediate using a reverse transcriptase enzyme, a process similar to retroviruses.
The other common human hepatitis viruses (A, C, D, and E) are all RNA viruses.

Option A: Hepatitis A virus (HAV) is an RNA virus, not a DNA virus. It has a single-stranded, positive-sense RNA genome and belongs to the Picornaviridae family.
Option C: Hepatitis C virus (HCV) is an RNA virus. It has a single-stranded, positive-sense RNA genome and is a member of the Flaviviridae family.
Option D: Hepatitis D virus (HDV), or the delta agent, is a defective RNA virus. It has a circular, single-stranded RNA genome and is unique because it requires the Hepatitis B virus surface antigen (HBsAg) to replicate.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Viral Genome Classification (Hepatitis Viruses) as background academic context rather than a clinical decision trigger.
Understanding the genetic material of each virus is fundamental for diagnosis (e.g., using DNA or RNA-based tests like PCR) and developing antiviral therapies that target specific viral replication steps.
The fact that Hepatitis D requires HBV for replication is clinically significant. This means that vaccinating a person against HBV also protects them from HDV infection.
A nurse's understanding of transmission routes and viral characteristics is vital for patient education and implementing appropriate infection control measures (e.g., standard precautions for bloodborne pathogens like HBV and HCV).

How to Approach the Question

First, identify the core of the question, which is to identify a 'DNA virus' from the given options.
The options are all types of hepatitis viruses (A, B, C, D). This is a factual recall question based on microbiology.
Mentally review or recall the classification of each hepatitis virus based on its genetic material (genome).
Recall that Hepatitis A, C, D, and E are RNA viruses.
Recall that Hepatitis B is the exception and is a DNA virus.
Select Hepatitis B as the correct answer and eliminate the other options as they are all RNA viruses.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 p. 547-549

E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 158-160

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Attempt every question from this paper in a timed mock, then review the full solution for each one.