Safety and Immunogenicity of Newborn MVA85A Vaccination and Selective, Delayed Bacille Calmette-Guerin for Infants of Human Immunodeficiency Virus-Infected Mothers: A Phase 2 Randomized, Controlled Trial

Abstract

Background: Vaccination of human immunodeficiency virus (HIV)-infected infants with bacille Calmette-Guérin (BCG) is contraindicated. HIV-exposed newborns need a new tuberculosis vaccination strategy that protects against tuberculosis early in life and avoids the potential risk of BCG disease until after HIV infection has been excluded.

Methods: This double-blind, randomized, controlled trial compared newborn MVA85A prime vaccination (1 × 108 PFU) vs Candin® control, followed by selective, deferred BCG vaccination at age 8 weeks for HIV-uninfected infants and 12 months follow-up for safety and immunogenicity.

Results: A total of 248 HIV-exposed infants were enrolled. More frequent mild-moderate reactogenicity events were seen after newborn MVA85A vaccination. However, no significant difference was observed in the rate of severe or serious adverse events, HIV acquisition (n = 1 per arm), or incident tuberculosis disease (n = 5 MVA85A; n = 3 control) compared to the control arm. MVA85A vaccination induced modest but significantly higher Ag85A-specific interferon gamma (IFNγ)+ CD4+ T cells compared to control at weeks 4 and 8 (P < .0001). BCG did not further boost this response in MVA85A vaccinees. The BCG-induced Ag85A-specific IFNγ+ CD4+ T-cell response at weeks 16 and 52 was of similar magnitude in the control arm compared to the MVA85A arm at all time points. Proliferative capacity, functional profiles, and memory phenotype of BCG-specific CD4 responses were similar across study arms.

Conclusions: MVA85A prime vaccination of HIV-exposed newborns was safe and induced an early modest antigen-specific immune response that did not interfere with, or enhance, immunogenicity of subsequent BCG vaccination. New protein-subunit and viral-vectored tuberculosis vaccine candidates should be tested in HIV-exposed newborns.

Clinical trials registration: NCT01650389.

Keywords: BCG; HIV-exposed infants; MVA85A; tuberculosis; vaccination.

Figure 1.

Study design (A) and CONSORT diagram (B). Abbreviations: BCG, bacille Calmette-Guérin; CONSORT, Consolidated Standards of Reporting Trials; HIV, human immunodeficiency virus; PCR, polymerase chain reaction; TB, tuberculosis.

Figure 2.

Ag85A-specific CD4 cytokine responses. Fresh whole blood was stimulated with Ag85A peptides for 12 hours prior to intracellular cytokine staining and flow cytometry analysis. A, Cross-sectional comparison of frequencies of Ag85A-specific CD4+ T cells expressing interferon gamma (IFNγ) in participants who were vaccinated with MVA85A (red) or control (black) at birth. Bacille Calmette-Guérin was administered to all participants at age 8 weeks. B, Longitudinal changes of Ag85A-specific CD4+ T cells expressing IFNγ are indicated by arrows (red for MVA85A arm and black for control arm). Medians and 95% confidence intervals (for the medians) are shown. C, Frequencies of Ag85A-specific CD4+ T cells expressing different combinations of IFNγ, tumor necrosis factor alpha, and interleukin 2 were compared between MVA85A arm (solid boxes) and control arm (clear boxes) at weeks 4 (blue), 8 (purple), 16 (green), and 52 (orange). Box and whiskers denote median, interquartile range, and minimum/maximum. Unadjusted P values were calculated by mixed effects models in A and B and by Mann-Whitney test in C. Abbreviations: BCG, bacille Calmette-Guérin; IFNγ, interferon gamma; IL, interleukin; TNFα, tumor necrosis factor alpha.

Figure 3.

Bacille Calmette-Guérin (BCG)-specific CD4 cytokine responses. Fresh whole blood was stimulated with BCG for 12 hours prior to intracellular cytokine staining and flow cytometry analysis. A, Longitudinal changes of BCG-specific CD4+ T cells expressing any combination of interferon gamma (IFNγ), tumor necrosis factor alpha (TNFα), interleukin (IL) 2, IL17, and/or IL22 are indicated by arrows (red for MVA85A arm and black for control arm). Medians and 95% confidence intervals (CIs; for the medians) are shown. Unadjusted P values were calculated by mixed effects models. B, Cytokine coexpression patterns of BCG-specific CD4 responses at week 16 (left) and week 52 (right) in the MVA85A (top) and control (bottom) arms by permutation test. Pies represent total BCG-specific CD4+ T cells expressing any cytokine; slices show the relative proportion of cells coexpressing 1 (blue), 2 (green), 3 (yellow), or 4 (orange) cytokines, identified by the external arcs: IFNγ (red), IL2 (black), IL17 (orange), IL22 (purple), and TNFα (dark green). C, Differentiation profiles were defined based on expression patterns of CD45RA and CCR7 as follows: naive-like (T_NL, CD45RA+ CCR7+), central memory (T_CM, CD45RA- CCR7+), effector (T_E, CD45RA- CCR7-), and terminal effector (T_TE, CD45RA+ CCR7-). Representative flow cytometry plot of BCG-specific cytokine+ CD4+ T cells (pink) overlaid on total CD4+ T cells (black). D, Longitudinal changes of BCG-specific cytokine+ CD4+ T cells expressing T_NL (maroon), T_CM (blue), T_E (orange), or T_TE (green) phenotype in MVA85A (left) or control (right) recipients. Medians and 95% CIs (for the medians) are shown. The number of participants meeting cutoff criteria for this analysis (see methods) is shown for each visit. Frequencies of all subsets significantly increased (P < .025) upon BCG vaccination (week 8 vs week 16) and decreased (P < .025) between week 16 and 52, with the exception of T_CM in the MVA85A arm. Unadjusted P values were calculated by Wilcoxon matched-pairs test; week 4 and 8 were not compared due to low numbers of paired samples (less than 10). No significant differences were observed when comparing frequencies of each subset at each visit between study arms. Abbreviations: BCG, bacille Calmette-Guérin; IFNγ, interferon gamma; IL, interleukin; TNFα, tumor necrosis factor alpha.

Figure 4.

CD4+ T cell proliferation in response to Ag85A and bacille Calmette-Guérin (BCG). Fresh whole blood was stimulated with Ag85A peptides or BCG for 7 days prior to intracellular staining of Ki67 and cytotoxic markers and flow cytometric analysis. Frequencies of Ag85A-specific (A) and BCG-specific (B) CD4+ T cells expressing the proliferation marker Ki67 were analyzed longitudinally in MVA85A (red lines and arrows) and control (black lines and arrows) arms. Medians and 95% confidence intervals (for the medians) are shown. Unadjusted P values were calculated by mixed effects models. C, Cytotoxic mediator coexpression patterns of BCG-specific CD4 responses were compared across study weeks in MVA85A arm (top) and control arm (bottom) by permutation test. No significant differences between study arms were observed at any visit. Pies represent total BCG-specific CD4+ T cells expressing Ki67, and slices represent the relative proportion of cells coexpressing cytotoxic markers identified by the external arcs: granzyme A (blue), granzyme B (red), granulysin (green), granzyme K (orange), and perforin (purple). Black slices denote the proportion of proliferating cells that do not express any cytotoxic marker. The number of participants meeting cutoff criteria for this analysis (see methods) is shown within each pie. Abbreviations: BCG, bacille Calmette-Guérin.