Background: Resiquimod, an investigational immune response modifier and Toll-like receptor (TLR) 7 and 8 agonist, stimulates production of cytokines that promote an antigen-specific T helper type 1 (Th1)--acquired immune response. In animal models, induction of Th1-specific responses modifies experimental herpes simplex virus (HSV) infection.
Methods: We conducted a randomized, double-blind, vehicle-controlled trial to assess the efficacy of resiquimod 0.01% gel for reducing human anogenital HSV-2 mucosal reactivation. Adults with genital HSV-2 applied resiquimod or vehicle topically to herpes lesions 2 times weekly for 3 weeks and then collected daily anogenital swabs for 60 days for HSV DNA polymerase chain reaction. Recurrences during the subsequent 7 months were treated with study gel. During the final treatment-free 60 days, participants again collected daily swabs to assess shedding.
Results: The median lesion and shedding rates were lower for resiquimod compared with vehicle recipients during the initial sampling period (10% vs. 16% [P=.03] and 10% vs. 17% [P=.08], respectively) and during the final sampling period (3% vs. 22% [P<.001] and 10% vs. 26% [P=.009], respectively). Resiquimod did not influence recurrence length.
Conclusions: These findings suggest that the immunological control of HSV-2 reactivation and lesion clearance may differ and that TLR7 and TLR8 agonists can reduce the frequency of mucosal HSV-2 reactivation.