Identification and immune assessment of T cell epitopes in five Plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimization
<p>The hurdles to effective blood stage malaria vaccine design include immune evasion tactics used by the parasite such as redundant invasion pathways and antigen variation among circulating parasite strains. While blood stage malaria vaccine development primarily focuses on eliciting optimal...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
Frontiers Media
2021
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| _version_ | 1826310690403516416 |
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| author | Kotraiah, V Phares, TW Terry, FE Hindocha, P Silk, SE Nielsen, CM Moise, L Tucker, KD Ashfield, R Martin, WD De Groot, AS Draper, SJ Gutierrez, GM Noe, AR |
| author_facet | Kotraiah, V Phares, TW Terry, FE Hindocha, P Silk, SE Nielsen, CM Moise, L Tucker, KD Ashfield, R Martin, WD De Groot, AS Draper, SJ Gutierrez, GM Noe, AR |
| author_sort | Kotraiah, V |
| collection | OXFORD |
| description | <p>The hurdles to effective blood stage malaria vaccine design include immune evasion tactics used by the parasite such as redundant invasion pathways and antigen variation among circulating parasite strains. While blood stage malaria vaccine development primarily focuses on eliciting optimal humoral responses capable of blocking erythrocyte invasion, clinically-tested <em>Plasmodium falciparum</em> (Pf) vaccines have not elicited sterile protection, in part due to the dramatically high levels of antibody needed. Recent development efforts with non-redundant, conserved blood stage antigens suggest both high antibody titer and rapid antibody binding kinetics are important efficacy factors. Based on the central role of helper CD4 T cells in development of strong, protective immune responses, we systematically analyzed the class II epitope content in five leading Pf blood stage antigens (RH5, CyRPA, RIPR, AMA1 and EBA175) using <em>in silico</em>, <em>in vitro</em>, and <em>ex vivo</em> methodologies. We employed <em>in silico</em> T cell epitope analysis to enable identification of 67 HLA-restricted class II epitope clusters predicted to bind a panel of nine HLA-DRB1 alleles. We assessed a subset of these for HLA-DRB1 allele binding <em>in vitro</em>, to verify the <em>in silico</em> predictions. All clusters assessed (40 clusters represented by 46 peptides) bound at least two HLA-DR alleles <em>in vitro</em>. The overall epitope prediction to <em>in vitro</em> HLA-DRB1 allele binding accuracy was 71%. Utilizing the set of RH5 class II epitope clusters (10 clusters represented by 12 peptides), we assessed stimulation of T cells collected from HLA-matched RH5 vaccinees using an IFN-γ T cell recall assay. All clusters demonstrated positive recall responses, with the highest responses – by percentage of responders and response magnitude – associated with clusters located in the N-terminal region of RH5. Finally, a statistically significant correlation between <em>in silico</em> epitope predictions and <em>ex vivo</em> IFN-γ recall response was found when accounting for HLA-DR matches between the epitope predictions and donor HLA phenotypes. This is the first comprehensive analysis of class II epitope content in RH5, CyRPA, RIPR, AMA1 and EBA175 accompanied by <em>in vitro</em> HLA binding validation for all five proteins and <em>ex vivo</em> T cell response confirmation for RH5.</p> |
| first_indexed | 2024-03-07T07:57:11Z |
| format | Journal article |
| id | oxford-uuid:38436532-af57-4c39-9352-91befd902181 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:57:11Z |
| publishDate | 2021 |
| publisher | Frontiers Media |
| record_format | dspace |
| spelling | oxford-uuid:38436532-af57-4c39-9352-91befd9021812023-08-25T07:04:40ZIdentification and immune assessment of T cell epitopes in five Plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimizationJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:38436532-af57-4c39-9352-91befd902181EnglishSymplectic ElementsFrontiers Media2021Kotraiah, VPhares, TWTerry, FEHindocha, PSilk, SENielsen, CMMoise, LTucker, KDAshfield, RMartin, WDDe Groot, ASDraper, SJGutierrez, GMNoe, AR<p>The hurdles to effective blood stage malaria vaccine design include immune evasion tactics used by the parasite such as redundant invasion pathways and antigen variation among circulating parasite strains. While blood stage malaria vaccine development primarily focuses on eliciting optimal humoral responses capable of blocking erythrocyte invasion, clinically-tested <em>Plasmodium falciparum</em> (Pf) vaccines have not elicited sterile protection, in part due to the dramatically high levels of antibody needed. Recent development efforts with non-redundant, conserved blood stage antigens suggest both high antibody titer and rapid antibody binding kinetics are important efficacy factors. Based on the central role of helper CD4 T cells in development of strong, protective immune responses, we systematically analyzed the class II epitope content in five leading Pf blood stage antigens (RH5, CyRPA, RIPR, AMA1 and EBA175) using <em>in silico</em>, <em>in vitro</em>, and <em>ex vivo</em> methodologies. We employed <em>in silico</em> T cell epitope analysis to enable identification of 67 HLA-restricted class II epitope clusters predicted to bind a panel of nine HLA-DRB1 alleles. We assessed a subset of these for HLA-DRB1 allele binding <em>in vitro</em>, to verify the <em>in silico</em> predictions. All clusters assessed (40 clusters represented by 46 peptides) bound at least two HLA-DR alleles <em>in vitro</em>. The overall epitope prediction to <em>in vitro</em> HLA-DRB1 allele binding accuracy was 71%. Utilizing the set of RH5 class II epitope clusters (10 clusters represented by 12 peptides), we assessed stimulation of T cells collected from HLA-matched RH5 vaccinees using an IFN-γ T cell recall assay. All clusters demonstrated positive recall responses, with the highest responses – by percentage of responders and response magnitude – associated with clusters located in the N-terminal region of RH5. Finally, a statistically significant correlation between <em>in silico</em> epitope predictions and <em>ex vivo</em> IFN-γ recall response was found when accounting for HLA-DR matches between the epitope predictions and donor HLA phenotypes. This is the first comprehensive analysis of class II epitope content in RH5, CyRPA, RIPR, AMA1 and EBA175 accompanied by <em>in vitro</em> HLA binding validation for all five proteins and <em>ex vivo</em> T cell response confirmation for RH5.</p> |
| spellingShingle | Kotraiah, V Phares, TW Terry, FE Hindocha, P Silk, SE Nielsen, CM Moise, L Tucker, KD Ashfield, R Martin, WD De Groot, AS Draper, SJ Gutierrez, GM Noe, AR Identification and immune assessment of T cell epitopes in five Plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimization |
| title | Identification and immune assessment of T cell epitopes in five Plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimization |
| title_full | Identification and immune assessment of T cell epitopes in five Plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimization |
| title_fullStr | Identification and immune assessment of T cell epitopes in five Plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimization |
| title_full_unstemmed | Identification and immune assessment of T cell epitopes in five Plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimization |
| title_short | Identification and immune assessment of T cell epitopes in five Plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimization |
| title_sort | identification and immune assessment of t cell epitopes in five plasmodium falciparum blood stage antigens to facilitate vaccine candidate selection and optimization |
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