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Adjuvanted multi-epitope vaccines protect HLA-A*11:01 transgenic mice against Toxoplasma gondii
Kamal El Bissati, … , Craig W. Roberts, Rima McLeod
Kamal El Bissati, … , Craig W. Roberts, Rima McLeod
Published September 22, 2016
Citation Information: JCI Insight. 2016;1(15):e85955. https://doi.org/10.1172/jci.insight.85955.
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Research Article Vaccines

Adjuvanted multi-epitope vaccines protect HLA-A*11:01 transgenic mice against Toxoplasma gondii

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Abstract

We created and tested multi-epitope DNA or protein vaccines with TLR4 ligand emulsion adjuvant (gluco glucopyranosyl lipid adjuvant in a stable emulsion [GLA-SE]) for their ability to protect against Toxoplasma gondii in HLA transgenic mice. Our constructs each included 5 of our best down-selected CD8+ T cell–eliciting epitopes, a universal CD4+ helper T lymphocyte epitope (PADRE), and a secretory signal, all arranged for optimal MHC-I presentation. Their capacity to elicit immune and protective responses was studied using immunization of HLA-A*11:01 transgenic mice. These multi-epitope vaccines increased memory CD8+ T cells that produced IFN-γ and protected mice against parasite burden when challenged with T. gondii. Endocytosis of emulsion-trapped protein and cross presentation of the antigens must account for the immunogenicity of our adjuvanted protein. Thus, our work creates an adjuvanted platform assembly of peptides resulting in cross presentation of CD8+ T cell–eliciting epitopes in a vaccine that prevents toxoplasmosis.

Authors

Kamal El Bissati, Aziz A. Chentoufi, Paulette A. Krishack, Ying Zhou, Stuart Woods, Jitender P. Dubey, Lo Vang, Joseph Lykins, Kate E. Broderick, Ernest Mui, Yasuhiro Suzuki, Qila Sa, Stephanie Bi, Nestor Cardona, Shiv K. Verma, Laura Fraczek, Catherine A. Reardon, John Sidney, Jeff Alexander, Alessandro Sette, Tom Vedvick, Chris Fox, Jeffrey A. Guderian, Steven Reed, Craig W. Roberts, Rima McLeod

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Figure 8

Multi-epitopes adjuvanted with GLA-SE are captured and presented by MHC molecules on the APCs to T lymphocytes.

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Multi-epitopes adjuvanted with GLA-SE are captured and presented by MHC ...
(A) HLA-A*11:01 transgenic mice immunized with LO protein plus GLA-SE were protected compared with control mice inoculated with PBS when they were challenged with 20,000 T. gondii prugneaud strain (Fluc) luciferase expressing parasites after 4 and 6 days. (n = 4 mice per group, 2 replicate experiments.) (B) Assay demonstrating that GLA-SE is a TLR4 ligand that leads to production of IL-6, IL-12, and TNF-α by PBMC. Stimulation of human whole blood with GLA-SE. Heparinized whole blood was collected from 6 healthy donors, and 200 μl was stimulated with 5 μg GLA-SE in 96-well plates at 37oC CO2. After 24 hours, plasma was removed and assayed for IL-6, IL-12(p40), and TNF-α by a custom Luminex-based multiplex immunoassay kit (Affymetrix eBioscience). Data were analyzed using the Masterplex QT software (Miraibio). The cytokine production stimulated by adjuvant was statistically significant for IL-6, IL-12, and TNF-α (P < 0.05) compared with the unstimulated groups as assessed by the Mann-Whitney U test (GraphPad Prism software). The plots show median, with box extending from the 25th to 75th percentile and the whiskers extending from minimum and maximum values of the data set. (C) Multi-epitope proteins with GLA-SE are captured by the Antigen-presenting cells (APCs), and the peptides contained are presented by MHC molecules on the APCs to T lymphocytes in both a class I and a class II pathway. This demonstrates that cross presentation into a class I pathway must occur by virtue of effector function. APCs are also activated through recognition of GLA-SE by TLR4 receptors molecules. This activation leads to the production of proinflammatory cytokines (IL-12, IL-6, TNF-α) and the expression of costimulatory molecules on the cell surface.

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