A 34-year-old man with HIV presents to clinic for evaluation of a rash that has progressively worsened over 3 months. He reports no pain or pruritus. He recently stopped taking his antiretroviral therapy. Physical examination shows dozens of 2–5 mm, flesh-colored, dome-shaped papules on the face, neck, trunk, and groin. Many have central umbilication. There is no inguinal lymphadenopathy. CD4 count is 68 cells/mm3.

Which of the following best explains why this patient is at risk for a prolonged course with widespread lesions?