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)

Development and characterization of viral inhibition assay (VIA) : a CD8T cell neutralization assay for use in clinical trials of HIV-1 vaccine candidates

We have characterized an assay measuring CD8+ T cell-mediated inhibition of human immunodeficiency virus (HIV) type 1 replication, demonstrating specificity and reproducibility and employing a panel of HIV -1 isolates. The assay uses relatively simple autologous cell culture and enzyme-linked immunosorbent assay (ELlSA), avoids generation of T cell clones and can be performed with <2 million peripheral blood mononuclear cells. Efficient CD8+ T cell-mediated cross-clade inhibition of HIV-I replication in vitro was demonstrated in antiretroviral therapy-naive HIV -l-infected subjects with controlled viral replication in vivo but not in viremic subjects. The observed HIV-I inhibition is reversed by blockade of MHC I and physical separation of effector CD8+ and target CD4+ T cells by transwell chambers. An HIV-I vaccine candidate, consisting of adenovirus (Ad) serotype 35 vectors tested in a phase I clinical trial, induced CD8+ T cells that efficiently inhibited HIV -1. Assessment of direct antiviral T cell function by this assay provides additional information to guide vaccine design and the prioritizing of candidates for further clinical trials. 2EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Broad HIV epitope specificity and viral inhibition induced by multigenic HIV-1 adenovirus subtype 35 vector vaccine in healthy uninfected adults

A correlation between in vivo and in vitro virus control mediated by CD8+ T-cell populations has been demonstrated by CD8 T-cell-mediated inhibition of HIV-1 and SIV replication in vitro in peripheral blood mononuclear cells (PBMCs) from infected humans and non-human primates (NHPs), respectively. Here, the breadth and specificity of T-cell responses induced following vaccination with replication-defective adenovirus serotype 35 (Ad35) vectors containing a fusion protein of Gag, reverse transcriptase (RT), Integrase (Int) and Nef (Ad35-GRIN) and Env (Ad35-ENV), derived from HIV-1 subtype A isolates, was assessed in 25 individuals. The vaccine induced responses to a median of 4 epitopes per vaccinee. We correlated the CD8 responses to conserved vs. variable regions with the ability to inhibit a panel of 7 HIV-1 isolates representing multiple clades in a virus inhibition assay (VIA). The results indicate that targeting immunodominant responses to highly conserved regions of the HIV-1 proteome may result in an increased ability to inhibit multiple clades of HIV-1 in vitro. The data further validate the use of the VIA to screen and select future HIV vaccine candidates. Moreover, our data suggest that future T cell-focused vaccine design should aim to induce immunodominant responses to highly conserved regions of the virus

Breadth of peptides recognized following vaccination with Ad35-GRIN and Ad35-ENV.

<p>Breadth of peptides recognized following vaccination with Ad35-GRIN and Ad35-ENV.</p

The effect of vaccine-induced CD8 responses targeting conserved regions on <i>in vitro</i> virus inhibition.

<p>A) box whisker plot comparing the average capacity to inhibit virus replication when targeted sequence is conserved, a Mann-Whitney test for unmatched pairs was used to determine that virus inhibition was significantly higher when vaccines recognized a putative epitope conserved within the relevant virus B) a box whisker plot illustrating that vaccines inhibiting viruses to highest levels recognize epitopes significantly more conserved than those inhibited to lesser levels (Mann Whitney t-test). C) Linear regression analysis relating average conservation of putative epitopes targeted to average inhibition of individual viruses top, IIIB virus is encircled. There is a slight trend towards inhibition of viruses where targeted putative epitopes were more conserved, IIIB is encircled as an outlier (left panel). Where IIIB is excluded (right panel) trend becomes more pronounced and approaches significance.</p

Reactive peptides inducing responses in CD8 populations ascertained through ICS and ELISpot using expanded CD8 populations, where possible peptides are associated with predefined optimal epitopes using vaccinee HLA.

<p>Bold sequences appear more than once and indicate a preferential immune targeting.</p

Breadth of insert-specific T-cell responses.

<p>Elispot peptide matrices were used to determine the number of possible epitopes recognized by vaccinees. Vaccinees (classified by Volunteer IDs) are stratified by dose and vaccine regimen.</p