A patient has unilateral lesions on the left palate (from teeth #9 to #14 area) and the left lip. What virus is responsible?

Herpes zoster (shingles) is caused by reactivation of varicella-zoster virus (VZV), which lies dormant in sensory ganglia after primary chickenpox infection. The hallmark is unilateral, dermatomal distribution of vesicular lesions that do not cross the midline. Oral lesions following the distribution of the maxillary division (V2) of the trigeminal nerve would involve the palate, maxillary gingiva, and lip on one side - exactly as described (#9 to #14 = left maxillary teeth). Management includes antiviral therapy (acyclovir, valacyclovir) initiated early to reduce severity and the risk of post-herpetic neuralgia.