Virology: interferon: practice question

A Microbiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Microbiology · Virology: interferon

Sample item

Which statement correctly describes the antiviral action of interferon?

AIt prevents viral attachment by blocking the receptorBIt acts only against the virus that induced itCIt binds viral particles and neutralises them directlyDIt induces PKR and 2',5'-oligoadenylate synthetase in uninfected cells, blocking viral protein synthesis

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. It induces PKR and 2',5'-oligoadenylate synthetase in uninfected cells, blocking viral protein synthesis

Double-stranded RNA made during viral replication induces type I interferons, which bind receptors on neighbouring cells and induce antiviral proteins. PKR phosphorylates eIF2 to halt translation, and 2',5'-oligoadenylate synthetase activates RNase L to degrade RNA. The effect is host-cell specific but virus non-specific.

Option by option

A. It prevents viral attachment by blocking the receptor
Interferon does not block receptors for attachment.
B. It acts only against the virus that induced it
Interferon acts against many viruses and is not virus-specific.
C. It binds viral particles and neutralises them directly
Direct neutralisation of virions is the function of antibodies.
D. It induces PKR and 2',5'-oligoadenylate synthetase in uninfected cells, blocking viral protein synthesis (correct)
Correct. Interferon induces enzymes in neighbouring cells that shut down viral protein synthesis.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, It induces PKR and 2',5'-oligoadenylate synthetase in uninfected cells, blocking viral protein synthesis. Double-stranded RNA made during viral replication induces type I interferons, which bind receptors on neighbouring cells and induce antiviral proteins.

Why is "It prevents viral attachment by blocking the receptor" not the answer?

Interferon does not block receptors for attachment.

Why is "It acts only against the virus that induced it" not the answer?

Interferon acts against many viruses and is not virus-specific.

Why is "It binds viral particles and neutralises them directly" not the answer?

Direct neutralisation of virions is the function of antibodies.

What concept does this question test?

It tests Virology: interferon in Microbiology. PKR phosphorylates eIF2 to halt translation, and 2',5'-oligoadenylate synthetase activates RNase L to degrade RNA. The effect is host-cell specific but virus non-specific.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Virology: interferon?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.