Immune Correlates of Herpes Zoster in People Living with HIV on Effective Antiretroviral Therapy.

Herpes zoster (HZ) has high morbidity in people living with HIV (PLHIV). We investigated immunological factors that correlated with the development of HZ in PLHIV with controlled HIV replication on antiretroviral therapy (ART). PLHIV who developed HZ on ART (cases), with undetectable plasma HIV RNA, and CD4 counts ≥200 cells/μL were matched 1:1 to controls by CD4 count, age, gender, race, and duration of ART. Varicella-zoster virus (VZV)-specific T cells and circulating regulatory T cells (Treg) were measured by flow cytometry before and after HZ. Differences between cases and controls were assessed by paired t-tests and longitudinal changes by Wilcoxon signed rank test. HZ cases (N = 31) had higher CD4+FOXP3+CD25+% Treg before HZ compared with 31 controls. After VZV ex vivo restimulation, cases had lower T cell responses, including CD8+perforin+% cytotoxic T lymphocytes (CTLs), CD4+IL10+%, and CD4+TGFβ+% compared with controls. Overall, Treg negatively correlated with VZV-specific Th1 responses. Moreover, Treg decreased over time on ART in HZ cases, VZV-CTLs were stable and did not increase even after HZ. Increased circulating Treg and decreased VZV-specific T cell immune responses were associated with the risk of HZ in PLHIV. The kinetics of Treg over time, but not of VZV-CTLs, paralleled the natural history of HZ, whose incidence decreases over time on effective ART.