Virology USMLE Step 1 Practice Question
A 39-year-old man with advanced HIV infection (CD4 count 45 cells/μL) presents with painful oral vesicles and fever (38.2°C). Despite 10 days of intravenous acyclovir (10 mg/kg every 8 hours), lesions persist and worsen. Viral sequencing confirms herpes simplex virus with resistance pattern. He denies prior antiviral prophylaxis. Which of the following viral abnormalities most likely explains this acyclovir resistance?
Answer choices
- AAbsent or altered viral thymidine kinaseCorrect answer
- BMutation of the M2 ion channel
- CLoss of neuraminidase activity
- DDeletion of viral protease
- EMutation in reverse transcriptase
- FAltered viral DNA polymerase with reduced acyclovir triphosphate binding
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