Thesis
Identification of CD4+ T cell-stimulating Plasmodium yoelii epitopes via in vivo immunopeptidomics
Master of Science (M.S.), Drexel University
May 2020
DOI:
https://doi.org/10.17918/00000285
Abstract
Plasmodium falciparum is the protozoan parasite that causes the most severe form of malaria in humans. An effective vaccine is required to achieve complete elimination of malaria. In addition to pre-erythrocytic stage parasites targeted by the partially-effective RTS,S vaccine, blood-stage parasites have also been shown to be neutralized by immune-mediated mechanisms. Currently, the development of blood-stage malaria vaccines is focused on eliciting high titers of antibodies against antigens on the surface of merozoites or infected erythrocytes. However, the efficacy of these antibody-focused vaccine attempts has been suboptimal. Published data suggest the need for a parasite-specific, IFN-[gamma]-producing CD4+ T cell response to eliminate blood-stage parasites. Here, we seek to identify the immunogenic peptides of blood-stage parasites displayed by the MHC Class II molecules of splenic antigen presenting cells (APCs) during acute Plasmodium yoelii blood-stage malaria. Protocols for isolation of MHC Class II + peptide complexes from splenic APCs by immunoprecipitation were optimized. Peptides from host and parasite proteins were eluted and analyzed by LC-MS/MS. The corresponding proteins were identified by searching murine and P. yoelii 17X genome databases. A total of 19 P. yoelii peptides were identified, 15 of them were unique and corresponded to 9 unique proteins. The predicted binding affinity of each peptide for MHC Class II was evaluated using bioinformatics tools available through the Immune Epitope Database and Analysis Resource. 13 putative P. yoelii T cell epitopes were assessed for the ability to stimulate memory CD4+ T cells isolated from malaria-immune mice. The results show that none of the identified peptides could be classified as immunodominant. No single peptide stimulated significant responses from memory T cells in all animals tested. Instead, a different set of peptides for each animal stimulated T cells to respond. This was somewhat unexpected as studies were conducted with inbred strains of mice. These findings suggest that alternate approaches will be needed to address the challenge of variability in the specificity of infection-induced CD4+ T cell responses in order to successfully develop a T cell-priming blood-stage malaria vaccine.
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Details
- Title
- Identification of CD4+ T cell-stimulating Plasmodium yoelii epitopes via in vivo immunopeptidomics
- Creators
- Matthew Joseph VanPelt
- Contributors
- James M. Burns (Advisor) - Drexel University, Microbiology and ImmunologyAkhil B. Vaidya (Advisor) - Drexel University, Microbiology and Immunology
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- viii, 139 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems (1997-2026); Drexel University
- Other Identifier
- 991014695142304721