Live attenuated varicella-zoster virus vaccine does not induce HIV target cell activation

Abstract

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 trials with adenovirus serotype 5-vectored (Ad5-vectored) HIV vaccine demonstrated increased HIV risk in individuals with pre-immunity to the vector that was thought to be associated with mucosal immune activation (IA). Therefore, given the prospect of developing an HIV/VZV chimeric vaccine, it is particularly important to define the impact of VZV vaccination on IA.

Methods: Healthy VZV-seropositive Kenyan women (n = 44) were immunized with high-dose live attenuated VZV vaccine, and we assessed the expression on CD4+ T cells isolated from blood, cervix, and rectum of IA markers including CD38 and HLA-DR and of markers of cell migration and tissue retention, as well as the concentration of genital and intestinal cytokines. A delayed-start 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 after vaccination when compared with 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 after vaccination.

Conclusion: This study provides the first evidence to our knowledge about the effects of VZV vaccination on human mucosal IA status and supports further evaluation of VZV as a potential vector for an HIV vaccine.

Trial registration: ClinicalTrials.gov NCT02514018.

Funding: Primary support from the Canadian Institutes for Health Research (CIHR). For other sources, see Acknowledgments.

Keywords: AIDS vaccine; AIDS/HIV; Cytokines; T cells; Vaccines.

Conflict of interest statement

Conflict of interest: SMM has received grants for unrelated studies from Merck, GlaxoSmithKline, Sanofi Pasteur, Pfizer, and Roche-Assurex. SMM has received fees as an advisory board member for Sanofi Pasteur.

Figures

Figure 1. KAVI-VZV 001 enrollment and follow-up diagram.

Figure 2. Immunization and sample collection schedule.

The primary endpoint was determined between week 12 after vaccination and week 0. PBMC, peripheral blood mononuclear cells; CC, cervical cells; CVS, cervicovaginal secretion; RC, rectal cells; RS, rectal secretion.

Figure 3. Cervical cellular IA markers.

(A) Representative flow cytometry plots for the identification of cervical CD4+ T cells, and CCR5+, CD69+, Ki-67+, CD38+HLA-DR+, and HLA-DR+ CD4+ T cells. Cells were pre-gated on lymphocytes, singlets, viability by LIVE/DEAD staining, and CD3+ cells. Expression of (B) CD38/HLA-DR, (C) HLA-DR, (D) CD69, (E) Ki-67, and (F) CCR5 on cervical CD4+ T cells prior to vaccination (weeks –12 to 0) and after vaccination (weeks +4 to +12). Graphs to the left show median with IQRs, and graphs to the right the comparison between weeks –12 and 0 and between weeks 0 and +12 for each of the graphs. Individuals in the immediate and delayed groups are shown in red and blue, respectively, and were grouped according to time from vaccination for this analysis. Time points were compared with week 0 using Wilcoxon’s signed-rank test. No significant change was observed between any of the time points (unadjusted for multiple comparisons).

Figure 4. Cervical soluble IA markers.

(A) Spearman’s correlation between cervico-vaginal cytokines (using log10-normalized concentrations). Only rs with P < 0.0005 are shown (n = 234). (B) Pattern matrix for the PCA showing loading of each cytokine on the principal components. PC1 explains 63% of variance, and PC2 and PC3 explain 11% and 8% of variance, respectively. Loads greater than 0.450 are highlighted. (C) PC1, (D) PC2, and (E) PC3 factor scores and (F) MIP-1β level prior to vaccination (weeks –12 to 0) and after vaccination (weeks +4 to +12). Graphs to the left show median with IQR, and graphs to the right the comparison between weeks –12 and 0 and between weeks 0 and +12 for each of the graphs. Individuals in the immediate and delayed groups are shown in red and blue, respectively, and were grouped according to time from vaccination for this analysis. Time points were compared to week 0 using Wilcoxon’s signed-rank test. No significant change was observed between any of the time points (unadjusted for multiple comparisons).

Figure 5. Impact of DMPA use and BV incidence on genital IA.

(A) PC factor score comparisons between records for DMPA users (n = 135) and for women using other hormonal contraceptives (n = 99). (B) Comparison between PC factor scores for BV+ records (n = 17) and BV– records (n = 217). Graphs show median with IQRs. **P < 0.01, ****P < 0.0001 as determined by a 2-tailed Mann-Whitney U test. (C) Paired comparison between PC factors for BV+ visits and the median for BV– visits for each participant who had BV during this period of the study. ***P < 0.001 calculated by Friedman’s test, followed by Wilcoxon’s signed-rank test, and adjusted for multiple comparisons using step-down procedure.

Figure 6. Rectal cellular IA markers.

(A) Representative flow cytometry plots for the identification of rectal CD4+ T cells, and CCR5+, CD69+, Ki-67+, CD38+HLA-DR+, and HLA-DR+ CD4+T cells. Cells were pre-gated on lymphocytes, singlets, live, and CD3+ cells. Expression of (B) CD38/HLA-DR, (C) HLA-DR, (D) CD69, (E) Ki-67, and (F) CCR5 on rectal CD4+ T cells prior to vaccination (weeks –12 and 0) and after vaccination (week +12). Graphs to the left show median with IQRs, and graphs to the right the comparison between weeks –12 and 0 and between weeks 0 and +12 for each of the graphs. Individuals in the immediate and delayed groups are shown in red and blue, respectively, and were grouped according to time from vaccination for this analysis. Time points were compared with week 0 using Friedman’s test, followed by Wilcoxon’s signed-rank test. P and P′ show P values unadjusted and adjusted for multiple comparisons using step-down procedure, respectively.

Figure 7. Rectal soluble IA markers.

(A) Spearman’s correlation between rectal cytokines (using log10-normalized concentrations). Only rs with P < 0.0005 are shown (n = 107). (B) Pattern matrix for the PCA showing loading of each cytokine on the principal components. PC1 explains 58% of variance, and PC2 and PC3 explain 14% and 7% of variance, respectively. Loads greater than 0.450 are highlighted. (C) PC1, (D) PC2, and (E) PC3 factor scores prior to vaccination (weeks –12 and 0) and after vaccination (week +12). Graphs to the left show median with IQRs, and graphs to the right the comparison between weeks –12 and 0 and between weeks 0 and +12 for each of the graphs. Individuals in the immediate and delayed groups are shown in red and blue, respectively, and were grouped according to time from vaccination for this analysis. Time points were compared with week 0 using Wilcoxon’s signed-rank test. No significant change was observed between any of the time points (unadjusted for multiple comparisons).