Robust antibody and cellular responses induced by DNA-only vaccination for HIV

Abstract

BACKGROUNDHVTN 098, a randomized, double-blind, placebo-controlled trial, evaluated the safety, tolerability, and immunogenicity of PENNVAX-GP HIV DNA vaccine, administered with or without plasmid IL-12 (pIL-12), via intradermal (ID) or intramuscular (IM) electroporation (EP) in healthy, HIV-uninfected adults. The study tested whether PENNVAX-GP delivered via ID/EP at one-fifth the dose could elicit equivalent immune responses to delivery via IM/EP and whether inclusion of pIL-12 provided additional benefit.METHODSParticipants received DNA encoding HIV-1 env/gag/pol in 3 groups: 1.6 mg ID (ID no IL-12 group, n = 20), 1.6 mg ID + 0.4 mg pIL-12 (ID + IL-12 group, n = 30), 8 mg IM + 1 mg pIL-12 (IM + IL-12 group, n = 30), or placebo (n = 9) via EP at 0, 1, 3, and 6 months. Results of cellular and humoral immunogenicity assessments are reported.RESULTSFollowing vaccination, the frequency of responders (response rate) to any HIV protein based on CD4+ T cells expressing IFN-γ or IL-2 was 96% for both the ID + IL-12 and IM + IL-12 groups; CD8+ T cell response rates were 64% and 44%, respectively. For ID delivery, the inclusion of pIL-12 increased CD4+ T cell response rate from 56% to 96%. The frequency of responders was similar (≥90%) for IgG binding antibody to gp140 consensus Env across all groups, but the magnitude was higher in the ID + IL-12 group compared with the IM + IL-12 group.CONCLUSIONPENNVAX-GP DNA induced robust cellular and humoral immune responses, demonstrating that immunogenicity of DNA vaccines can be enhanced by EP route and inclusion of pIL-12. ID/EP was dose sparing, inducing equivalent, or in some aspects superior, immune responses compared with IM/EP.TRIAL REGISTRATIONClinicalTrials.gov NCT02431767.FUNDINGThis work was supported by National Institute of Allergy and Infectious Diseases (NIAID), U.S. Public Health Service grants, an HIV Vaccine Design and Development Team contract, Integrated Preclinical/Clinical AIDS Vaccine Development Program, and an NIH award.

Keywords: AIDS vaccine; Infectious disease; T cells; Vaccines.

Figure 1. HVTN 098 CONSORT diagram.

Figure 2. T cell responses measured by ICS.

(A) CD4⁺ and CD8⁺ T cells expressing IFN-γ or IL-2 to any HIV peptide pool. Positive responses are shown in filled circles in color; negative responses are shown in open gray triangles. Box plots represent the distribution for the positive responders only (the upper and lower quartiles and the median). Bar plots show response rates. Numbers below the bars indicate numbers of positive responders and total participants. Assays were performed 2 weeks after the third and fourth vaccinations and 6 months after the fourth vaccination. (B) COMPASS CD4⁺ and CD8⁺ T cell polyfunctionality scores (PFSs) to any HIV Env peptide pool. (C) Heatmaps for CD4⁺ and CD8⁺ T cell responses to Any Env peptide pool showing the mean posterior probabilities of antigen-specific responses from COMPASS. Columns correspond to the different subsets of cytokines being considered grouped from left to right by increasing number of functions in the key below the heatmap; a filled box indicates cells in that column are expressing that function, with different colors indicating cells with 1, 2, 3, 4, or 5 functions. Rows correspond to mean across the individual participants in each treatment group at each time point. Each cell shows the probability that the corresponding antigen-specific subset (column) is being expressed in the corresponding treatment group in average (row) and is color-coded ranging from 0 (white) to 1 (dark purple). Positive response rates were compared using the Fisher exact test for unpaired data (between treatment groups) and the McNemar test for paired data (between visits). Response magnitudes among positive responders were compared using the Wilcoxon rank sum test for unpaired data and the Wilcoxon signed rank test for paired data. All P values are 2 sided. False discovery rate–adjusted q values were calculated to account for multiple antigens, multiple time points, or treatment groups.

Figure 3. IgG binding antibody responses, as measured by binding antibody multiplex assay against consensus Env gp140 and gp120 antigens, Env gp41, and Gag p24.

Assays were performed 2 weeks after the third and fourth vaccinations and 6 months after the fourth vaccination. Positive responses are shown in filled circles in color; negative responses are shown in open gray triangles. Box plots represent the distribution for the positive responders only (the upper and lower quartiles and the median). Bar plots show response rates. Numbers below the bars indicate numbers of positive responders and total participants. Positive response rates were compared using the Fisher exact test for unpaired data (between treatment groups) and the McNemar test for paired data (between visits). Response magnitudes among positive responders were compared using the Wilcoxon rank sum test for unpaired data and the Wilcoxon signed rank test for paired data. All P values are 2 sided. False discovery rate–adjusted q values were calculated to account for multiple antigens, multiple time points, or treatment groups.

Figure 4. IgG binding antibody responses as measured by binding antibody multiplex assay against clade AE (A244) Env V1V2.

Positive responses are shown in filled circles in color; negative responses are shown in open gray triangles. Box plots represent the distribution for the positive responders only (the upper and lower quartiles and the median). Response rates are listed above each graph along with numbers of positive responders and total participants. Positive response rates were compared using the Fisher exact test for unpaired data (between treatment groups) and the McNemar test for paired data (between visits). Response magnitudes among positive responders were compared using the Wilcoxon rank sum test for unpaired data and the Wilcoxon signed rank test for paired data. All P values are 2 sided. False discovery rate–adjusted q values were calculated to account for multiple antigens, multiple time points, or treatment groups.

Figure 5. IgG3 binding antibody responses as measured by binding antibody multiplex assay against consensus Env gp140 and Env gp41.

Positive responses are shown in filled circles in color; negative responses are shown in open gray triangles. Box plots represent the distribution for the positive responders only (the upper and lower quartiles and the median). Bar plots show response rates. Numbers below the bars indicate numbers of positive responders and total participants. Positive response rates were compared using the Fisher exact test for unpaired data (between treatment groups) and the McNemar test for paired data (between visits). Response magnitudes among positive responders were compared using the Wilcoxon rank sum test for unpaired data and the Wilcoxon signed rank test for paired data. All P values are 2 sided. False discovery rate–adjusted q values were calculated to account for multiple antigens, multiple time points, or treatment groups.

Figure 6. Antibody functional responses.

(A) Neutralizing antibody responses to tier 1A Env-pseudotyped virus MW965.26 as determined by the TZM-bl neutralization assay 2 weeks after the third and fourth vaccinations. (B) ADCP 2 weeks after the fourth vaccination. (C) ADCC as determined by the infected cell target assay for a clade C viral isolate (TV1). For all plots, positive responses are shown in filled circles in color; negative responses are shown in open gray triangles. Box plots represent the distribution for the positive responders only (the upper and lower quartiles and the median). Response rates are listed above each graph along with numbers of positive responders and total participants. Response magnitudes among positive responders were compared using the Wilcoxon signed rank test; P values are 2 sided.