A human immune data-informed vaccine concept elicits strong and broad T-cell specificities associated with HIV-1 control in mice and macaques

Abstract

BackgroundNone of the HIV T-cell vaccine candidates that have reached advanced clinical testing have been able to induce protective T cell immunity. A major reason for these failures may have been suboptimal T cell immunogen designs.MethodsTo overcome this problem, we used a novel immunogen design approach that is based on functional T cell response data from more than 1,000 HIV-1 clade B and C infected individuals and which aims to direct the T cell response to the most vulnerable sites of HIV-1.ResultsOur approach identified 16 regions in Gag, Pol, Vif and Nef that were relatively conserved and predominantly targeted by individuals with reduced viral loads. These regions formed the basis of the HIVACAT T-cell Immunogen (HTI) sequence which is 529 amino acids in length, includes more than 50 optimally defined CD4+ and CD8+ T-cell epitopes restricted by a wide range of HLA class I and II molecules and covers viral sites where mutations led to a dramatic reduction in viral replicative fitness. In both, C57BL/6 mice and Indian rhesus macaques immunized with an HTI-expressing DNA plasmid (DNA.HTI) induced broad and balanced T-cell responses to several segments within Gag, Pol, and Vif. DNA.HTI induced robust CD4+ and CD8+ T cell responses that were increased by a booster vaccination using modified virus Ankara (MVA.HTI), expanding the DNA.HTI induced response to up to 3.2% IFN-γ T-cells in macaques. HTI-specific T cells showed a central and effector memory phenotype with a significant fraction of the IFN-γ+ CD8+ T cells being Granzyme B+ and able to degranulate (CD107a+).ConclusionsThese data demonstrate the immunogenicity of a novel HIV-1 T cell vaccine concept that induced broadly balanced responses to vulnerable sites of HIV-1 while avoiding the induction of responses to potential decoy targets that may divert effective T-cell responses towards variable and less protective viral determinants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0392-5) contains supplementary material, which is available to authorized users.

DNA Prime-Boost Vaccine Regimen To Increase Breadth, Magnitude, and Cytotoxicity of the Cellular Immune Responses to Subdominant Gag Epitopes of Simian Immunodeficiency Virus and HIV

“…Analysis of Gag-specific responses was performed using pools of 15-mer peptides. Ag-specific T cells were measured by intracellular cytokine staining followed by polychromatic flow cytometry as detailed elsewhere (32,39,42) using the following mixture of cell surface Abs: CD3-APCCy7 (clone SP34-2), CD4-V500 (clone L200), CD95-FITC (clone DX2) (BD Pharmingen, San Diego, CA), CD8-Alexa Fluor-405 (clone 3B5; Invitrogen), CD28-PerCP Cy5.5 (clone CD28.2; BioLegend, San Diego, CA). Ten minutes after addition of peptides, the CD107a-eFluor 660 (clone eBioH4A3; eBioscience, San Diego, CA) Ab was added.…”

Increased T cell breadth and antibody response elicited in prime-boost regimen by viral vector encoded homologous SIV Gag/Env in outbred CD1 mice

“…A shift to more focused constructs aimed to direct CD8+ T cells specifically to carefully selected regions has therefore been a logical step forward. Conserved regions vaccines [14, 21] and conserved elements (CE) vaccines [22] each represents approaches aiming to overcome the challenge of HIV-1 diversity and raise responses to rarely targeted, yet protective specificities [23]. …”

Gag and env conserved element CE DNA vaccines elicit broad cytotoxic T cell responses targeting subdominant epitopes of HIV and SIV Able to recognize virus-infected cells in macaques

“…76 , 77 Analysis of SIV Env-specific responses was performed using a pool of 15-mer peptides overlapping by 11 AA covering the full-length protein sequence. Antigen-specific T cells were measured by intracellular cytokine staining followed by polychromatic flow cytometry 22 , 76 , 77 , 86 using the following cocktail of cell surface antibodies: CD3-APCCy7 (clone SP34-2), CD4-V500 (clone L200), CD95-FITC (clone DX2) (Cat #557757, 561488, 556640, respectively, BD Pharmingen), CD8-Alexa Fluor-405 (clone 3B5, Cat #MHCD0826, Invitrogen) and CD28-PerCP Cy5.5 (clone CD28.2, Cat #302922, BioLegend). Ten minutes after addition of peptides, the CD107a-eFluor 660 or CD107a-PE antibody (clone eBioH4A3, Cat #50-1079-41, 50-1079-42, respectively, ThermoFisher) was added.…”