Virology: prion disease: 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: prion disease

Sample item

A 62-year-old woman has rapidly progressive dementia and startle myoclonus over 3 months. EEG shows periodic sharp wave complexes, and brain pathology shows spongiform change. Which property of the causative agent is correct?

AAn enveloped RNA virus inactivated by formalinBA DNA virus that causes latent infection in neuronsCA misfolded protein that is resistant to proteinase K and to routine sterilisationDA cell-wall-deficient bacterium sensitive to doxycycline

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

The answer and the reasoning

C. A misfolded protein that is resistant to proteinase K and to routine sterilisation

Creutzfeldt-Jakob disease is a prion disease in which the normal cellular protein PrPC is converted into a beta-sheet-rich form, PrPSc, that resists proteases and conventional sterilisation. There is no nucleic acid and no inflammatory response, and CSF 14-3-3 protein may be raised. Special decontamination is needed for instruments.

Option by option

A. An enveloped RNA virus inactivated by formalin
The agent has no RNA genome and is not inactivated by formalin.
B. A DNA virus that causes latent infection in neurons
No DNA virus is responsible, as the agent lacks nucleic acid.
C. A misfolded protein that is resistant to proteinase K and to routine sterilisation (correct)
Correct. The infectious agent is a protease-resistant misfolded protein.
D. A cell-wall-deficient bacterium sensitive to doxycycline
The agent is not a bacterium, so antibiotics are ineffective.

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 C, A misfolded protein that is resistant to proteinase K and to routine sterilisation. Creutzfeldt-Jakob disease is a prion disease in which the normal cellular protein PrPC is converted into a beta-sheet-rich form, PrPSc, that resists proteases and conventional sterilisation.

Why is "An enveloped RNA virus inactivated by formalin" not the answer?

The agent has no RNA genome and is not inactivated by formalin.

Why is "A DNA virus that causes latent infection in neurons" not the answer?

No DNA virus is responsible, as the agent lacks nucleic acid.

Why is "A cell-wall-deficient bacterium sensitive to doxycycline" not the answer?

The agent is not a bacterium, so antibiotics are ineffective.

What concept does this question test?

It tests Virology: prion disease in Microbiology. There is no nucleic acid and no inflammatory response, and CSF 14-3-3 protein may be raised. Special decontamination is needed for instruments.

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: prion disease?

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.