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Question #46509
The Question
A patient recovers from a viral infection, generating memory B-cells. The virus subsequently undergoes rapid antigenic drift, significantly altering the structural conformation of its surface epitopes. Upon re-exposure to this mutated strain, the patient's serum is immediately tested using an indirect ELISA coated with the mutated viral antigens. Which of the following correctly describes the physiological immune response and the diagnostic outcome?
Options
- A.
An anamnestic (secondary) response is triggered due to B-cell memory, and the ELISA yields a strong positive result due to high IgG titers.
- B.
A primary immune response is initiated, and the indirect ELISA initially yields a negative result because pre-existing antibodies lack complementarity to the mutated epitopes.
- C.
An anamnestic response is triggered, but the ELISA yields a negative result because ELISA relies exclusively on detecting pathogen DNA, which has mutated.
- D.
A primary immune response is initiated, but the ELISA yields a strong positive result because memory T-cells cross-react with the mutated antigens in the assay.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Antigen-Antibody Specificity|Secondary Immune Response Kinetics|Enzyme-linked immunosorbent assay
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that 'immunological memory' to a specific virus guarantees a secondary response and a positive antibody test indefinitely.
This question forces the synthesis of evolutionary biology (antigenic drift) with molecular diagnostics (ELISA lock-and-key specificity).
If the epitope changes, both the biological memory response and the in-vitro diagnostic test fail to recognize it.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Human Health and Disease - Class 12 |
| Concept | Primary vs Secondary Immune Response |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |