Association between quantitative varicella-zoster virus antibody levels and zoster reactivation in HIV-infected persons

BACKGROUND: Varicella-zoster virus (VZV) reactivation is common but difficult to predict in HIV-infected persons. OBJECTIVE: Since qualitative VZV antibodies can determine past VZV disease or vaccination, we evaluated whether quantitative VZV antibody levels over time can predict future zoster. STUDY DESIGN: US Military HIV Natural History (NHS) participants with a zoster diagnosis at least 5 years after HIV diagnosis (n = 100) were included. Zoster-negative controls (n = 200) were matched by age, race, gender, and CD4 count at HIV diagnosis. Repository plasma specimens collected at baseline and prior to zoster diagnosis were evaluated using a quantitative anti-VZV ELISA assay. Differences in quantitative VZV levels were analyzed by Wilcoxon Mann–Whitney and Fisher’s exact tests. RESULTS: Median CD4 count at HIV diagnosis was similar for cases and controls (535 [IQR 384–666] vs. 523 [IQR 377–690] cells/μL; p = 0.940), but lower for cases at zoster diagnosis (436 [IQR 277–631] vs. 527 [IQR 367–744] cells/μL; p = 0.007). Antiretroviral therapy (ART) use prior to zoster diagnosis was lower for cases (52.0%) compared to controls (64.5%; p = 0.025). Cases had similar mean VZV antibody levels prior to zoster diagnosis compared to controls [2.25 ± 0.85 vs. 2.44 ± 0.96 index value/optical density (OD) ratio; p = 0.151] with no difference in the change in antibody levels over time (0.08 ± 0.71 vs. 0.01 ± 0.94 index value/OD per year; p = 0.276). CONCLUSION: Quantitative VZV antibody levels are stable in HIV-infected persons and do not predict zoster reactivation. Low CD4 count and lack of ART use appear to be better predictors of future zoster diagnosis.