Engineering and characterization of a novel Self Assembling Protein for Toxoplasma peptide vaccine in HLA-A*11:01, HLA-A*02:01 and HLA-B*07:02 transgenic mice

Kamal El Bissati,Senthil K Raman,Rima Mcleod,Peter Burkhard,Ashley Estes,Joseph Lykins,Christopher P Karch,Steve Reed,Ying Zhou,Amber Estes,Sara M Paulillo

doi:10.1038/s41598-020-73210-0

Abstract

Fighting smart diseases requires smart vaccines. Novel ways to present protective immunogenic peptide epitopes to human immune systems are needed. Herein, we focus on Self Assembling Protein Nanoparticles (SAPNs) as scaffolds/platforms for vaccine delivery that produce strong immune responses against Toxoplasma gondii in HLA supermotif, transgenic mice. Herein, we present a useful platform to present peptides that elicit CD4+, CD8+ T and B cell immune responses in a core architecture, formed by flagellin, administered in combination with TLR4 ligand-emulsion (GLA-SE) adjuvant. We demonstrate protection of HLA-A*11:01, HLA-A*02:01, and HLA-B*07:02 mice against toxoplasmosis by (i) this novel chimeric polypeptide, containing epitopes that elicit CD8+ T cells, CD4+ T helper cells, and IgG2b antibodies, and (ii) adjuvant activation of innate immune TLR4 and TLR5 pathways. HLA-A*11:01, HLA-A*02:01, and HLA-B*07:02q11 transgenic mouse splenocytes with peptides demonstrated predicted genetic restrictions. This creates a new paradigm-shifting vaccine approach to prevent toxoplasmosis, extendable to other diseases.

Highlights

Human Leukocyte Antigen (HLA)-*A02:01, HLA-B*07:02, and CD4+ T cell eliciting epitopes are attached to the N-terminal end of the protein chain, while B-cell eliciting epitope, MIC1 appears to be hidden in the assembled particle
We combined MIC1 Self Assembling Protein Nanoparticles (SAPNs) with the prototype that carries the five HLA-A*11:01 epitopes, one HLA-B*07:02 and four HLA-A*02:01 T. gondii CD8+ T cell eliciting epitopes, the C D4+ T cell eliciting epitope PADRE intercalated into the flagellin portion of the design (Fig. 2a)
The ToxAll presented here represents the first SAPN for the delivery of C D4+, CD8+ T cell eliciting and B cell eliciting epitopes with testing in different HLA transgenic mice

Summary

Introduction

We developed a novel type of SAPN, called Prototype 2, that contains five HLA-A*11:01-restricted CD8+ T cell epitopes (Fig. 1a) This Prototype 2 incorporates the TLR5 agonist flagellin as a a scaffold and as an immunopotentiator to make a self-adjuvanting SAPN11 (patent application E P1415060018). This multiepitope construct has been shown to induce IFN-γ and protect against type II parasites in HLA-A*11:01 mice, demonstrating the ability of the SAPNs to improve vaccine potency of CD8-based immunization a pproaches[11]. Our study of ToxAll demonstrated the ability to elicit antibodies against the B cell epitope MIC1 in a humoral immune response and at the same time it delivered the specific HLA supermotif -restricted C D8+ and C D4+ epitopes to elicit a cellular immune response

Methods

Results

Discussion

Conclusion