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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Categories: Research Article Vaccines

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

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 Frazeck, 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 1

Testing of peptides with PBMCs from HLA-A03 supertype T.

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Testing of peptides with PBMCs from HLA-A03 supertype T. gondiiseroposi...
gondiiseropositive and seronegative donors. (A) PBMC from donors who were seropositive and seronegative for T. gondii were tested for response to predicted HLA-A03 –restricted CD8+ T cell epitopes. Individual peptides were tested using IFN-γ ELISpot assay. (B) Concanavalin A (Con A) and tachyzoite antigen lysates (TLA) were used as controls. In A, experiments were performed 3 times. A representative experiment with one seropositive and one seronegative person shows the variability for each individual. For each person for each peptide, there were 6 determinations (wells). Each symbol represents one of these measurements of IFN-γ. The horizontal line is the mean of these 6 determinations with the SD shown. In B, methods, numbers of determinations, and comparisons were the same as for the peptides but were for Con A and TLA stimulation as controls. In 3 replicate experiments, PBMCs also were obtained from 3 T. gondii seropositive and 3 T. gondii seronegative HLA-A03 individuals. In these experiments, in the comparison of 3 seropositive and 3 seronegative persons, differences between the seropositive and seronegative persons were significant for each peptide when tested by Student’s t test (P < 0.05; n = 3 per group, data not shown). Stimulation for seropositive and seronegative persons for TLA were different and achieved statistical significance (P < 0.05). In contrast, stimulation with Con A demonstrated response of PBMC from both seronegative and seropositive donors (data not shown).