The Safety and Immunogenicity of GTU®MultiHIV DNA Vaccine Delivered by Transcutaneous and Intramuscular Injection With or Without Electroporation in HIV-1 Positive Subjects on Suppressive ART

International audiencePrevious studies have shown targeting different tissues via the transcutaneous (TC) and intramuscular injection (IM) with or without electroporation (EP) has the potential to trigger immune responses to DNA vaccination. The CUTHIVTHER 001 Phase I/II randomized controlled clinical trial was designed to determine whether the mode of DNA vaccination delivery (TC+IM or EP+IM) could influence the quality and function of induced cellular immune responses compared to placebo, in an HIV positive clade B cohort on antiretroviral therapy (ART). The GTU®MultiHIV B DNA vaccine DNA vaccine encoded a MultiHIV B clade fusion protein to target the cellular response. Overall the vaccine and regimens were safe and well-tolerated. There were robust pre-vaccination IFN-γ responses with no measurable change following vaccination compared to placebo. However, modest intracellular cytokine staining (ICS) responses were seen in the TC+IM group. A high proportion of individuals demonstrated potent viral inhibition at baseline that was not improved by vaccination. These results show that HIV positive subjects with nadir CD4+ counts ≥250 on suppressive ART display potent levels of cellular immunity and viral inhibition, and that DNA vaccination alone is insufficient to improve such responses. These data suggest that more potent prime-boost vaccination strategies are likely needed to improve pre-existing responses in similar HIV-1 cohorts (This study has been registered at http://ClinicalTrials.gov under registration no. NCT02457689)

A comparative phase I study of combination, homologous subtype-C DNA, MVA, and Env gp140 protein/adjuvant HIV vaccines in two immunization regimes

There remains an urgent need for a prophylactic HIV vaccine. We compared combined MVA and adjuvanted gp140 to sequential MVA/gp140 after DNA priming. We expected Env-specific CD4+ T-cells after DNA and MVA priming, and Env-binding antibodies in 100% individuals after boosting with gp140 and that combined vaccines would not compromise safety and might augment immunogenicity. Forty volunteers were primed three times with DNA plasmids encoding (CN54) env and (ZM96) gag-pol-nef at 0, 4 and 8 weeks then boosted with MVA-C (CN54 env and gag-pol-nef) and glucopyranosyl lipid adjuvant-aqueous formulation (GLA-AF) adjuvanted CN54gp140. They were randomised to receive them in combination at the same visit at 16 and 20 weeks (accelerated) or sequentially with MVA-C at 16, 20, and GLA-AF/gp140 at 24 and 28 weeks (standard). All vaccinations were intramuscular. Primary outcomes included ≥grade 3 safety events and the titer of CN54gp140-specific binding IgG. Other outcomes included neutralization, binding antibody specificity and T-cell responses. Two participants experienced asymptomatic ≥grade 3 transaminitis leading to discontinuation of vaccinations, and three had grade 3 solicited local or systemic reactions. A total of 100% made anti-CN54gp140 IgG and combining vaccines did not significantly alter the response; geometric mean titer 6424 (accelerated) and 6578 (standard); neutralization of MW965.2 Tier 1 pseudovirus was superior in the standard group (82 versus 45% responders,  = 0.04). T-cell ELISpot responses were CD4+ and Env-dominant; 85 and 82% responding in the accelerated and standard groups, respectively. Vaccine-induced IgG responses targeted multiple regions within gp120 with the V3 region most immunodominant and no differences between groups detected. Combining MVA and gp140 vaccines did not result in increased adverse events and did not significantly impact upon the titer of Env-specific binding antibodies, which were seen in 100% individuals. The approach did however affect other immune responses; neutralizing antibody responses, seen only to Tier 1 pseudoviruses, were poorer when the vaccines were combined and while T-cell responses were seen in >80% individuals in both groups and similarly CD4 and Env dominant, their breadth/polyfunctionality tended to be lower when the vaccines were combined, suggesting attenuation of immunogenicity and cautioning against this accelerated regimen

Glucopyranosyl lipid A adjuvant significantly enhances HIV specific T and B cell responses elicited by a DNA-MVA-protein vaccine regimen

Using a unique vaccine antigen matched and single HIV Clade C approach we have assessed the immunogenicity of a DNA-poxvirus-protein strategy in mice and rabbits, administering MVA and protein immunizations either sequentially or simultaneously and in the presence of a novel TLR4 adjuvant, GLA-AF. Mice were vaccinated with combinations of HIV env/gag-pol-nef plasmid DNA followed by MVA-C (HIV env/gag-pol-nef) with HIV CN54gp140 protein (+/−GLA-AF adjuvant) and either co-administered in different muscles of the same animal with MVA-C or given sequentially at 3-week intervals. The DNA prime established a population of B cells that were able to mount a statistically significant anamnestic response to the boost vaccines. The greatest antigen-specific antibody response was observed in animals that received all vaccine components. Moreover, a high proportion of the total mucosal IgG (20 – 50%) present in the vaginal vault of these vaccinated animals was vaccine antigen-specific. The potent elicitation of antigen-specific immune responses to this vaccine modality was also confirmed in rabbits. Importantly, co-administration of MVA-C with the GLA-AF adjuvanted HIV CN54gp140 protein significantly augmented the antigen-specific T cell responses to the Gag antigen, a transgene product expressed by the MVA-C vector in a separate quadriceps muscle. We have demonstrated that co-administration of MVA and GLA-AF adjuvanted HIV CN54gp140 protein was equally effective in the generation of humoral responses as a sequential vaccination modality thus shortening and simplifying the immunization schedule. In addition, a significant further benefit of the condensed vaccination regime was that T cell responses to proteins expressed by the MVA-C were potently enhanced, an effect that was likely due to enhanced immunostimulation in the presence of systemic GLA-AF

Modelling cytomegalovirus replication patterns in the human host: factors important for pathogenesis

Human cytomegalovirus can cause a diverse range of diseases in different immunocompromised hosts. The pathogenic mechanisms underlying these diseases have not been fully elucidated, though the maximal viral load during infection is strongly correlated with the disease. However, concentrating on single viral load measures during infection ignores valuable information contained during the entire replication history up to the onset of disease. We use a statistical model that allows all viral load data sampled during infection to be analysed, and have applied it to four immunocompromised groups exhibiting five distinct cytomegalovirus-related diseases. The results show that for all diseases, peaks in viral load contribute less to disease progression than phases of low virus load with equal amount of viral turnover. The model accurately predicted the time of disease onset for fever, gastrointestinal disease and pneumonitis but not for hepatitis and retinitis, implying that other factors may be involved in the pathology of these diseases

Murine vaccination groups.

<p>Female BALB/c mice received immunizations at three week intervals either sequentially or in combination into different quadricep muscles.</p

Vaccine elicited CN54gp140-specific serum and mucosal IgG responses in rabbits.

<p>Male and female NZW rabbits were primed with three DNA inoculations (8 mg total; 4 mg each leg) into their quadricep muscles then boosted with either MVA – gp140+GLA given sequentially or MVA/gp140+GLA administered concurrently in separate leg muscles (MVA-C at 1.3×10⁸ PFU in 500 µl; CN54gp140 at 100 µg in 400 µl; GLA-AF at 5 µg in 400 µl – co-formulated with CN54gp140 recombinant protein). The antigen-specific serum IgG response over the course of the vaccine regimen (<b>A</b>) and the mucosal IgG response at termination (<b>B</b>). Antigen-specific rabbit IgG antibody was assessed by an immunoglobulin ELISA with a rabbit purified IgG standard curve. Antigen-specific IgG concentrations are shown in µg/ml (+/− SEM).</p

Rabbit vaccination groups.

<p>Male and female NZW rabbits received immunizations at three week intervals either sequentially or in combination into different quadricep muscles. The reduced quantity of GLA-AF when compared with the murine experiments more closely models the amount that will be administered in humans, a refinement based on our repeat experiments where we found that immune stimulation elicited by 5 ug GLA-AF was equivalent to 20 ug GLA-AF. The regime-shortened group DNA-MVA/gp140+GLA animals were euthanized at week 21, while the sequential immunisation and control animals were euthanized at week 29, to fulfil the requirement for toxological analysis.</p

Gp140-Specific Serum IgG responses in mice primed with DNA.

<p>(<b>A</b>) Animals (<i>n</i> = 10) were inoculated 3 times with 100 µg plasmid DNA (IM at week 0, 3 and 6) then boosted with variations of MVA-C (10⁷ PFU) and/or recombinant protein with/without GLA-AF adjuvant (IM inoculation at week 12 and 15). CN54gp140 recombinant protein (10 µg) and GLA-AF adjuvant (20 µg) were admixed and injected into one quadricep muscle. If MVA-C was administered at the same time it was inoculated into the other quadricep muscle. Serum was taken one day prior to each vaccination and the antigen-specific IgG antibody was assessed by an immunoglobulin ELISA with a murine purified IgG standard curve. (<b>B</b>) Comparison of the serum IgG or IgA levels in each DNA primed group at peak response (Week 15). Antigen-specific IgG concentrations are shown in µg/ml (+/− SEM). Statistical comparisons were performed using a Mann-Whitney test (***<i>p</i><0.0001, comparison to DNA – MVA-C group).</p