A 32-year-old man from Delhi presents to the clinic with a 3-month history of progressive weight loss (8 kg), chronic diarrhea, and recurrent oral candidiasis. He reports unprotected sexual contact with multiple partners. On examination, he has oral thrush and generalized lymphadenopathy. CD4+ count is 180 cells/μL. Western blot confirms HIV-1 infection. Which of the following best describes the primary mechanism by which HIV-1 establishes persistent infection despite vigorous immune responses?