Virology USMLE Step 1 Practice Question

A 32-year-old woman with no significant past medical history presents to the emergency department with a 2-day history of severe bifrontal headache, photophobia, and neck stiffness. Temperature is 39.1°C, blood pressure 132/84 mmHg, heart rate 104 bpm, and respirations 16/min. On examination, she is alert and oriented with positive Kernig and Brudzinski signs. Lumbar puncture reveals cerebrospinal fluid with 145 lymphocytes/μL (90% mononuclear), glucose 52 mg/dL (serum glucose 98 mg/dL), and protein 72 mg/dL. Gram stain and bacterial culture are negative. PCR testing confirms herpes simplex virus type 1 (HSV-1). Neuroimaging shows temporal lobe involvement without mass effect. Which of the following antiviral agents is contraindicated in the treatment of this patient's condition?