Varicella-Zoster Virus-Specific Enzyme-Linked Immunospot Assay Responses and Zoster-Associated Pain in Herpes Zoster Subjects

Varicella-zoster virus (VZV)-specific cell-mediated immunity (CMI) responses were compared over time following an episode of herpes zoster (HZ) with those of age-, race-, and gender-matched healthy controls (HC) without HZ, using a validated gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay. The zoster brief-pain inventory (ZBPI) was used to assess zoster-associated pain. HZ patients (n = 140) had significantly higher IFN-γ ELISPOT responses to VZV antigen than did HC (n = 140). ELISPOT geometric mean count (GMC) responses (with 95% confidence intervals [CI]) for subjects who presented within 72 h were as follows: for HZ patients ≥ 60 years of age, at day 0 the GMC was 110 and at week 2 the GMC was 235; for HZ patients 21 to 59 years of age, at day 0 the GMC was 111 and at week 2 the GMC was 198; for HC ≥ 60 years of age, at day 0 the GMC was 19 and at week 2 the GMC was 18; and for HC 21 to 59 years of age, at day 0 the GMC was 59 and at week 2 the GMC was 56. The mean pain score (95% CI) across age groups at 1 week postrash (n = 106) was 6.0 (5.5, 6.5) and at 2 weeks postrash (n = 119) was 3.5 (2.9, 4.0). The percentage of HZ patients with substantial pain (score ≥ 3) at 6 weeks postrash increased with age from 8% for patients 21 to 49 years of age to 16% for patients 50 to 59 years of age to 22% for patients ≥ 60 years of age. The VZV-specific CMI response was substantially boosted by an episode of HZ, as measured by ELISPOT results. Older adults had lower VZV-specific cellular immunity than younger subjects at baseline, but the boosting effect of HZ was substantial for all age groups. HZ patients experienced considerable zoster-associated acute (1 to 2 weeks after rash) pain across age groups, while chronic pain increased with age.