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Question #46534
The Question
In gene therapy for Adenosine Deaminase (ADA) deficiency, a retroviral vector is used to deliver functional ADA cDNA into the patient's lymphocytes. Unlike wild-type HIV, which actively replicates and causes systemic infection, the modified retroviral vector cannot produce new viral progeny inside the host cell. This inability to cause 'systemic fallout' is primarily because the vector:
Options
- A.
Lacks the pre-packaged reverse transcriptase enzyme within its viral core during initial entry into the lymphocyte.
- B.
Fails to integrate its genetic material into the host genome due to the deletion of the viral integrase gene.
- C.
Is disarmed by the deletion of viral genes (gag, pol, env), preventing the assembly and release of new viral particles.
- D.
Contains a modified RNA genome that is directly translated into the ADA enzyme without undergoing reverse transcription.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Retroviral_Vector|ADA|Helper_T_cells
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Differentiating between the 'genes' carried by a viral vector and the 'proteins' packaged within its capsid.
A common misconception is that a 'disarmed' retrovirus lacks reverse transcriptase entirely.
While it lacks the gene (pol) to synthesize new enzymes for progeny, the initial viral particle must carry the pre-synthesized enzyme to facilitate the initial RNA-to-DNA conversion.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Human Health and Disease - Class 12 |
| Concept | HIV Replication Cycle |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |