Virology USMLE Step 1 Practice Question
A 70-year-old man presents with fever (39.2°C), cough, and dyspnea during a sudden influenza pandemic caused by a novel strain. Vital signs show HR 108, RR 22, BP 138/82, SpO2 92% on room air. Chest X-ray reveals bilateral interstitial infiltrates. Rapid influenza test is positive; hemagglutinin and neuraminidase antigens are not recognized by sera from prior human seasons. He denies recent travel. Which viral mechanism most likely produced this novel strain?
Answer choices
- APoint mutation in viral polymerase
- BAcquisition of a bacterial plasmid
- CReassortment of segmented RNA genomesCorrect answer
- DIntegration of proviral DNA into host chromosomes
- EReverse transcription of viral RNA into cDNA in the cytoplasm
- FRecombination of viral RNA with host mRNA during co-infection
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