First published December 4, 2018 - More info
BACKGROUND. Varicella-zoster virus (VZV) is under consideration as a promising recombinant viral vector to deliver foreign antigens including HIV. However, new vectors have come under increased scrutiny since vaccination with Ad5-vectored HIV vaccine trials demonstrated increased HIV risk in individuals with pre-immunity to the vector which was thought to be associated with mucosal immune activation (IA). Therefore, defining the impact of VZV vaccination on IA is particularly important with the prospect of developing an HIV/VZV chimeric vaccine. METHODS. VZV-seropositive healthy Kenyan women (n=44) were immunized with high dose live-attenuated VZV vaccine, and the expression of IA markers including CD38 and HLA-DR on CD4 T cells isolated from blood, cervix and rectum, markers of cell migration and tissue retention and the concentration of genital and intestinal cytokines were assessed. A delayed group (n=22) was used to control for natural variations in these parameters. RESULTS. Although immunogenic, VZV vaccination did not result in significant difference in the frequency of cervical activated (HLA-DR+CD38+) CD4 T cells (median 1.61%, IQR 0.93%-2.76%) at 12 weeks post-vaccination when compared to baseline (median 1.58%, IQR 0.75%-3.04%), the primary outcome for this study. VZV vaccination also had no measurable effect on any of the IA parameters at 4, 8 and 12 weeks post-vaccination. CONCLUSION. This study provides the first-ever evidence about the effects of VZV-vaccination on human mucosal IA status and supports further evaluation of VZV as a potential vector in an HIV vaccine. TRIAL REGISTRATION. ClinicalTrials.gov NCT02514018. FUNDING. Primary support from CIHR. For others see below.