Question

Which one of the following enzymes is required to ensure the replication of a negative-sense or negative-strand RNA virus?

• A. DNA-dependent RNA polymerase
• B. DNA polymerase
• C. RNA-dependent DNA polymerase
• D. RNA-dependent RNA polymerase

Answer 1

The Correct Option is D

To solve this question, we need to understand the nature of a negative-sense or negative-strand RNA virus and the enzyme required for its replication. Let's break it down step by step:

1. Understanding Negative-Sense RNA Viruses:
   • Negative-sense RNA viruses contain RNA that is complementary to the viral mRNA. This means their RNA cannot be directly translated by ribosomes to produce proteins.
   • To synthesize proteins, the negative-sense RNA must first be converted into a positive-sense RNA (the mRNA equivalent) through a process called transcription.
2. The Role of RNA-dependent RNA Polymerase:
   • Negative-sense RNA viruses have to transcribe their RNA into mRNA. This process requires a specific enzyme that reads the negative-sense RNA to synthesize a positive-sense RNA.
   • The enzyme required for this function is RNA-dependent RNA polymerase (RdRp).
   • RNA-dependent RNA polymerase catalyzes the replication of RNA from an RNA template, a critical step for the virus to eventually produce proteins and replicate.
3. Eliminating Incorrect Options:
   • DNA-dependent RNA polymerase: This enzyme synthesizes RNA from a DNA template, not applicable to RNA viruses.
   • DNA polymerase: This enzyme synthesizes DNA from a DNA template, irrelevant for RNA virus replication.
   • RNA-dependent DNA polymerase: This enzyme converts RNA into DNA, typically involved in reverse transcription, not directly necessary for RNA-only virus replication.
4. Conclusion:
   • The correct answer is RNA-dependent RNA polymerase, as it is directly required for the replication of negative-sense RNA viruses by converting their genome into a readable mRNA form.