Viruses contain which of the following as their genetic material?

AIIMS CRE, SNO-2024

Applied Microbiology & Infection control

Easy

Appeared in: AIIMS CRE, SNO-2024

Explanation

Viruses are defined by having a genome composed of either DNA or RNA, but never both within the same particle.
This is a fundamental distinction from cellular organisms (e.g., bacteria, eukaryotes), which use DNA as their permanent genome and RNA for various roles in gene expression.
The viral genome can be single-stranded (ss) or double-stranded (ds), further diversifying viral types.
Examples of RNA viruses include Influenza and HIV, while examples of DNA viruses include Herpesviruses and Adenoviruses.

Option A: This option is too restrictive. Many clinically important viruses, such as retroviruses (HIV) and orthomyxoviruses (influenza), are RNA viruses.
Option B: This option is also too restrictive. Many common viruses, such as adenoviruses (common cold), papillomaviruses (HPV), and herpesviruses (cold sores, chickenpox), are DNA viruses.
Option D: This is incorrect by the definition of a virus. All viruses possess a nucleic acid genome (genetic material) to encode the information needed for replication. Infectious agents without genetic material are prions, not viruses.

Visual 1: Diagram - A comparative illustration showing the basic structure of an RNA virus (like Influenza) and a DNA virus (like Adenovirus), highlighting the different types of genetic material within their capsids.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Genetic material of viruses as background academic context rather than a clinical decision trigger.
The type of genetic material (RNA vs. DNA) determines a virus's replication strategy and mutation rate. RNA viruses, which use less stable polymerases, tend to mutate faster (e.g., Influenza, SARS-CoV-2), leading to new strains and challenges for vaccine effectiveness.
This distinction is critical for diagnostics. For example, Reverse Transcriptase PCR (RT-PCR) is used for RNA viruses to first convert RNA to DNA, while standard PCR is sufficient for DNA viruses.
Antiviral drug development often targets enzymes specific to the viral genome type, such as reverse transcriptase inhibitors for retroviruses (RNA viruses) or DNA polymerase inhibitors for herpesviruses (DNA viruses).

How to Approach the Question

First, identify the core concept of the question, which is the composition of a virus's genetic material.
Recall the fundamental definition of a virus: an infectious agent with a nucleic acid core (genome) and a protein coat (capsid).
Remember the key distinction between viruses and cellular organisms: cells have both DNA and RNA, whereas a single virus particle has either DNA or RNA.
Evaluate the options based on this rule. 'Only DNA' and 'Only RNA' are too restrictive, as many examples exist for both types. 'Neither RNA nor DNA' is incorrect by definition.
Conclude that the most accurate and inclusive description is 'RNA or DNA'.

Concept Tested & Keywords

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