Sequential Immunization with gp140 Boosts Immune Responses Primed by Modified Vaccinia Ankara or DNA in HIV-Uninfected South African Participants

Abstract

Background: The safety and immunogenicity of SAAVI DNA-C2 (4 mg IM), SAAVI MVA-C (2.9 x 109 pfu IM) and Novartis V2-deleted subtype C gp140 (100 mcg) with MF59 adjuvant in various vaccination regimens was evaluated in HIV-uninfected adults in South Africa.

Methods: Participants at three South African sites were randomized (1:1:1:1) to one of four vaccine regimens: MVA prime, sequential gp140 protein boost (M/M/P/P); concurrent MVA/gp140 (MP/MP); DNA prime, sequential MVA boost (D/D/M/M); DNA prime, concurrent MVA/gp140 boost (D/D/MP/MP) or placebo. Peak HIV specific humoral and cellular responses were measured.

Results: 184 participants were enrolled: 52% were female, all were Black/African, median age was 23 years (range, 18-42 years) and 79% completed all vaccinations. 159 participants reported at least one adverse event, 92.5% were mild or moderate. Five, unrelated, serious adverse events were reported. The M/M/P/P and D/D/MP/MP regimens induced the strongest peak neutralizing and binding antibody responses and the greatest CD4+ T-cell responses to Env. All peak neutralizing and binding antibody responses decayed with time. The MVA, but not DNA, prime contributed to the humoral and cellular immune responses. The D/D/M/M regimen was poorly immunogenic overall but did induce modest CD4+ T-cell responses to Gag and Pol. CD8+ T-cell responses to any antigen were low for all regimens.

Conclusions: The SAAVI DNA-C2, SAAVI MVA-C and Novartis gp140 with MF59 adjuvant in various combinations were safe and induced neutralizing and binding antibodies and cellular immune responses. Sequential immunization with gp140 boosted immune responses primed by MVA or DNA. The best overall immune responses were seen with the M/M/P/P regimen.

Trial registration: ClinicalTrials.gov NCT01418235.

Conflict of interest statement

The authors have read the journal's policy and the authors of this manuscript have the following competing interests: MA and MP are employed by the National Institute of Allergy and Infectious Diseases (NIAID), the study sponsor. GC, KM, SK, CW, A-LW, LM, GDT, SCD, PG, NG, CY, GG, LGB, DCM, JK, LC were recipients of NIAID funding, and this publication is a result of activities funded by NIAID. MA and MP were not involved with the process of funding these awards, nor in their administration or scientific aspects, and, in accordance with NIAID policies, are deferred from decisions regarding funding of coauthors for a requisite period. This study was also partly funded by Novartis Vaccines. At the time the study was conducted, Susan W. Barnett was an employee and stakeholder of Novartis Vaccines and Diagnostics. This does not alter our adherence to PLOS ONE policies on sharing data and materials (as detailed online in the guide for authors, http://www.PLOSone.org/static/editorial.action#competing).

Figures

Fig 1. CONSORT flow diagram: number of individuals assessed for eligibility, enrolled and randomized to vaccine or placebo, followed-up and analysed.

T1: MVA prime, sequential gp140 boost (M/M/P/P); T2 (MP/MP): concurrent MVA/gp140; T3 (D/D/M/M): DNA prime, sequential MVA boost; T4 (D/D/MP/MP): DNA prime, concurrent MVA/gp140 boost) or placebo. P1-P4 = placebo.

Fig 2. Local and systemic reactinogenicity by treatment group.

Local and systemic reactinogenicity for the pooled placebo and each vaccine regimen (T1-T4) are shown in the top and bottom panel respectively. None, mild, moderate and severe reactions are colour coded blue, yellow, orange and red respectively. T1: MVA prime, sequential gp140 boost (M/M/P/P); T2 (MP/MP): concurrent MVA/gp140; T3 (D/D/M/M): DNA prime, sequential MVA boost; T4 (D/D/MP/MP): DNA prime, concurrent MVA/gp140 boost) or placebo. Two-sided unadjusted p-values from Fisher’s exact tests were used to compare proportions of participants that had local or systemic reactions between each pair of vaccine arms.

Fig 3. Peak neutralizing antibody titers.

TZM-bl neutralizing antibody titers by treatment group at peak immunogenicity (2 weeks post last vaccination) over the panel of 5 virus isolates (Tier 1: Clade B [MN.3, SF162], Clade C [MW925]; Tier 2: Clade C [Du151.2, TV1.21]). Each dot represents an individual, with data from responders in red and non-responders in blue. Box plots based on data from responders only are shown. The mid-line of the box denotes the median and the ends of the box denote the 25th and 75th percentiles. Whiskers extend to the extreme data points that are no more than 1.5 times the interquartile range or if no value meets this criterion, to the data extremes. The number and percent positive responders in each group are shown above the graphs. T1: MVA prime, sequential gp140 boost (M/M/P/P); T2: (MP/MP): concurrent MVA/gp140; T3 (D/D/M/M): DNA prime, sequential MVA boost; T4 (D/D/MP/MP): DNA prime, concurrent MVA/gp140 boost) or placebo.

Fig 4. Peak neutralizing antibody–magnitude breadth curves.

Average magnitude-breadth (MB) curves in the TZM-bl assay at peak immunogenicity (2 weeks post last vaccination) by treatment group. The area under the curve (AUC)-MB across all subjects in each group was calculated as the average of the log10 neutralizing antibody titers over the panel of 5 virus isolates (Tier 1: Clade B [MN.3, SF162], Clade C [MW965.26]; Tier 2: Clade C [Du151.2, TV1.21]). T1: MVA prime, sequential gp140 boost (M/M/P/P); T2 (MP/MP): concurrent MVA/gp140; T3 (D/D/M/M): DNA prime, sequential MVA boost; T4(D/D/MP/MP): DNA prime, concurrent MVA/gp140 boost) or placebo. Holm-Bonferroni adjusted p-values from unequal-variance t-tests were used for testing different mean AUC-MBs between vaccine arms accounting for the six pairs of vaccine arm comparisons.

Fig 5. Kinetics of neutralizing antibody responses.

TZM-bl neutralizing antibody titers by treatment group at all time-points, including the decay time point (visit 14). Neutralizing antibody titers against the viruses (A). MW965.26 (Clade C; Tier 1) and (B) MN.3 (Clade B; Tier 1), that had the highest responses at the peak immunogenicity time point are shown. Each dot represents an individual, with data from responders in red and non-responders in blue. Box plots based on data from responders only are shown. The number and percent positive responders in each group are shown above the graphs. T1: MVA prime, sequential gp140 boost (M/M/P/P), peak responses at visit 12; T2: concurrent MVA/gp140 (MP/MP), peak responses at visit 9; T3: DNA prime, sequential MVA boost (D/D/M/M), peak responses at visit 12; T4: DNA prime, concurrent MVA/gp140 boost (D/D/MP/MP), peak responses at visit 12. The decay kinetics time point was measured at visit 14, 6 months after last vaccination of M/M/P/P, D/D/P/P and D/D/MP/MP and 9 months after last vaccination of MP/MP.

Fig 6. Peak IgG binding antibody response.

Binding magnitude of IgG responses to gp120 and gp140 antigens are shown as mean fluorescent intensity (MFI) in top, middle and lower panels, respectively. Positive responders are indicated in red and negative responders in blue. The mid-line of the box denotes the median and the ends of the box denote the 25th and 75th percentiles. The whiskers that extend from the top and bottom of the box extend to the most extreme data points that are no more than 1.5 times the interquartile range (i.e., height of the box) or if no value meets this criterion, to the data extremes. The number and percent positive responders in each group are shown above the graphs. Placebo recipients from all treatment groups are shown together. T1: MVA prime, sequential gp140 boost (M/M/P/P); T2 (MP/MP): concurrent MVA/gp140; T3 (D/D/M/M): DNA prime, sequential MVA boost; T4 (D/D/MP/MP): DNA prime, concurrent MVA/gp140 boost) or placebo.

Fig 7. Kinetics of IgA binding antibody responses to Con S gp140 CFI.

Binding magnitude of IgA responses to Con S gp140 CFI is shown as mean fluorescent intensity (MFI) in top, middle and lower panels, respectively. Positive responders are indicated in red and negative responders in blue. The mid-line of the box denotes the median and the ends of the box denote the 25th and 75th percentiles. The whiskers that extend from the top and bottom of the box extend to the most extreme data points that are no more than 1.5 times the interquartile range (i.e., height of the box) or if no value meets this criterion, to the data extremes. The number and percent positive responders in each group are shown above the graphs. Placebo recipients from all treatment groups are shown together. T1: MVA prime, sequential gp140 boost (M/M/P/P); T2 (MP/MP): concurrent MVA/gp140; T3 (D/D/M/M): DNA prime, sequential MVA boost; T4 (D/D/MP/MP): DNA prime, concurrent MVA/gp140 boost) or placebo.

Fig 8. Kinetics of IgG binding antibody responses.

The geometric mean (and 95% error bars) of net responders are shown for visit 9, 12 and 14. T1: MVA prime, sequential gp140 boost (M/M/P/P), peak responses at visit 12; T2: concurrent MVA/gp140 (MP/MP), peak responses at visit 9; T3: DNA prime, sequential MVA boost (D/D/M/M), peak responses at visit 12; T4: DNA prime, concurrent MVA/gp140 boost (D/D/MP/MP), peak responses at visit 12. The decay kinetics time point was measured at visit 14, 6 months after last vaccination of M/M/P/P, D/D/P/P and D/D/MP/MP and 9 months after last vaccination of MP/MP.

Fig 9. Peak T-cell responses to vaccine antigens.

CD4+ and CD8+ background-adjusted T-cell responses as determined by intracellular cytokine staining 2 weeks following the fourth vaccination in groups 1, 3 and 4 (month 6.5) and following the second vaccination in group 2 (month 3.5). Because of overlap of peptides between PTEg peptide pools for the same HIV protein, the magnitude for the protein is calculated as the maximum among the peptide pools for the protein. The overall magnitude is calculated as the sum of the individual HIV protein magnitudes. Plots include data from responders in red and non-responders in blue. Box plots based upon data from responders only are superimposed on the distributions. The mid-line of the box denotes the median and the ends of the box denote the 25th and 75th percentiles. The whiskers that extend from the top and bottom of the box extend to the most extreme data points that are no more than 1.5 times the interquartile range (i.e., height of the box) or if no value meets this criterion, to the data extremes. The number and percent positive responders in each group are shown above the graphs. Placebo recipients from all treatment groups are shown together. T1 (M/M/P/P): MVA prime, sequential gp140 boost; T2 (MP/MP): concurrent MVA/gp140; T3 (D/D/M/M): DNA prime, sequential MVA boost; T4 (D/D/MP/MP): DNA prime, concurrent MVA/gp140 boost) or placebo.

Fig 10. Polyfunctionality analysis of peak CD4+ T-cell Env-specific responses.

Only responses positive for IFN-γ and/or IL-2 are shown; data are for the Env pool with the largest response within each individual at the peak timepoint for each treatment group. The upper left graph shows the proportion of Env-specific cells expressing the indicated number of functions. Total Env-specific cells are determined as cells producing any of the 5 functions alone or in combination, except that granzyme B must be co-expressed with another function since it is constitutively expressed. The next graphs show the proportion of cells within each degree of functionality expressing the indication combinations of functions. T1 (M/M/P/P): MVA prime, sequential gp140 boost; T2 (MP/MP): concurrent MVA/gp140; T3 (D/D/M/M): DNA prime, sequential MVA boost; T4 (D/D/MP/MP): DNA prime, concurrent MVA/gp140 boost) or placebo.