Immunopathology: HIV: practice question

A Pathology 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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Pathology · Immunopathology: HIV

Sample item

A researcher studies why a small number of people with a homozygous deletion in a chemokine co-receptor remain uninfected despite repeated HIV exposure. Which interaction is blocked in these individuals?

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

The answer and the reasoning

C. Binding of viral gp120 to CCR5 after CD4 attachment on macrophage-tropic strains

HIV gp120 first binds CD4 and then a co-receptor, CCR5 for early R5 virus or CXCR4 for later strains, which allows gp41-mediated fusion. People homozygous for the CCR5 delta-32 deletion are largely resistant to infection.

Option by option

  • A. Binding of the Tat protein to CD4

    Tat is a regulatory protein for transcription and does not bind CD4.

  • B. Binding of viral gp41 to CD8

    gp41 mediates membrane fusion and does not bind CD8.

  • C. Binding of viral gp120 to CCR5 after CD4 attachment on macrophage-tropic strains (correct)

    Correct. CCR5 is the co-receptor needed for entry of R5-tropic HIV.

  • D. Reverse transcription by viral integrase

    Integrase inserts proviral DNA and reverse transcription is performed by reverse transcriptase.

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.

More Pathology questions

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is C, Binding of viral gp120 to CCR5 after CD4 attachment on macrophage-tropic strains. HIV gp120 first binds CD4 and then a co-receptor, CCR5 for early R5 virus or CXCR4 for later strains, which allows gp41-mediated fusion.

Why is "Binding of the Tat protein to CD4" not the answer?

Tat is a regulatory protein for transcription and does not bind CD4.

Why is "Binding of viral gp41 to CD8" not the answer?

gp41 mediates membrane fusion and does not bind CD8.

Why is "Reverse transcription by viral integrase" not the answer?

Integrase inserts proviral DNA and reverse transcription is performed by reverse transcriptase.

What concept does this question test?

It tests Immunopathology: HIV in Pathology. People homozygous for the CCR5 delta-32 deletion are largely resistant to infection.

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 Immunopathology: HIV?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.