Virology: severe dengue and antibody-dependent enhancement: 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: severe dengue and antibody-dependent enhancement

Sample item

An adolescent who had dengue 3 years ago develops shock and plasma leakage after a second dengue illness caused by a different serotype. Which mechanism best explains the severity?

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

The answer and the reasoning

A. Antibody-dependent enhancement of infection

Non-neutralising cross-reactive antibody from the first infection binds the new serotype and promotes uptake into Fc receptor-bearing cells, increasing viral load and cytokine release. This explains why secondary infection carries a higher risk of severe dengue.

Option by option

  • A. Antibody-dependent enhancement of infection (correct)

    Correct. Antibody-dependent enhancement increases infection of monocytes.

  • B. Direct neurotoxin action

    Dengue does not produce a neurotoxin.

  • C. Superantigen activation of T cells

    Superantigens are described in toxic shock, not dengue.

  • D. Loss of the viral envelope

    Loss of envelope would reduce infectivity.

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.

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Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is A, Antibody-dependent enhancement of infection. Non-neutralising cross-reactive antibody from the first infection binds the new serotype and promotes uptake into Fc receptor-bearing cells, increasing viral load and cytokine release.

Why is "Direct neurotoxin action" not the answer?

Dengue does not produce a neurotoxin.

Why is "Superantigen activation of T cells" not the answer?

Superantigens are described in toxic shock, not dengue.

Why is "Loss of the viral envelope" not the answer?

Loss of envelope would reduce infectivity.

What concept does this question test?

It tests Virology: severe dengue and antibody-dependent enhancement in Microbiology. This explains why secondary infection carries a higher risk of severe dengue.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: severe dengue and antibody-dependent enhancement?

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.