Dataset Information

Mutations in epitope flanking regions for SARS-CoV-2 nucleoprotein affect proteasomal processing to alter CD8+ T cell responses

ABSTRACT: Viral CD8+ epitopes are generated by the cellular turnover of viral proteins, predominantly by the proteasome1. Mutations located within viral epitopes can result in escape from memory T cells2. Focussing on two of the most dominant SARS-CoV-2 nucleoprotein CD8+ epitopes3,4, we identified mutations in epitope flanking regions. Using SARS-CoV-2 nucleoprotein transduced B cell lines and in vitro proteasomal processing of peptides, we investigated the contribution of these mutations to antigen processing and T cell activation. We found that decreased NP9-17-B*27:05 CD8+ T cell responses to the NP-Q7K mutation correlated with lower epitope surface expression, likely due to a lack of efficient epitope production by the proteasome and suggesting an immune escape caused by this mutation. In contrast, NP-P6L and NP-D103N/Y mutations flanking the NP9-17-B*27:05 and NP105-113-B*07:02 epitopes, respectively, increased CD8+ T cell responses associated with enhanced epitope production by the proteasome. Our results provide evidence that SARS-CoV-2 mutations outside the epitope could have significant impact on antigen processing and presentation, thereby contributing to escape from immunodominant T cell responses. Alternatively, mutations could enhance antigen processing and T cell efficacy, opening new avenues for improving future vaccine designs.

INSTRUMENT(S): timsTOF Pro

ORGANISM(S): Recombinant Sars Coronavirus

DISEASE(S): Covid-19

SUBMITTER: Zhanru Yu

LAB HEAD: Roman Fischer

PROVIDER: PXD032054 | Pride | 2023-10-24

REPOSITORIES: Pride

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SARS-CoV-2 mutations affect antigen processing by the proteasome to alter CD8+ T cell responses.

Wellington Dannielle D Yin Zixi Z Yu Zhanru Z Heilig Raphael R Davis Simon S Fischer Roman R Felce Suet Ling SL Antoun Elie E Hublitz Philip P Beveridge Ryan R Dong Danning D Liu Guihai G Yao Xuan X Peng Yanchun Y Kessler Benedikt M BM Dong Tao T

Heliyon 20230914 10

Mutations within viral epitopes can result in escape from T cells, but the contribution of mutations in flanking regions of epitopes in SARS-CoV-2 has not been investigated. Focusing on two SARS-CoV-2 nucleoprotein CD8+ epitopes, we investigated the contribution of these flanking mutations to proteasomal processing and T cell activation. We found decreased NP9-17-B*27:05 CD8+ T cell responses to the NP-Q7K mutation, likely due to a lack of efficient epitope produ ...[more]

PMID: 37842619

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Project description:Sanjuan2013 - Evolution of HIV T-cell epitope, immune activation model Model of cellular immune response against HIV. This model is described in the article: Immune activation promotes evolutionary conservation of T-cell epitopes in HIV-1. Sanjuán R, Nebot MR, Peris JB, Alcamí J. PLoS Biol. 2013 Apr;11(4):e1001523 Abstract: The immune system should constitute a strong selective pressure promoting viral genetic diversity and evolution. However, HIV shows lower sequence variability at T-cell epitopes than elsewhere in the genome, in contrast with other human RNA viruses. Here, we propose that epitope conservation is a consequence of the particular interactions established between HIV and the immune system. On one hand, epitope recognition triggers an anti-HIV response mediated by cytotoxic T-lymphocytes (CTLs), but on the other hand, activation of CD4(+) helper T lymphocytes (TH cells) promotes HIV replication. Mathematical modeling of these opposite selective forces revealed that selection at the intrapatient level can promote either T-cell epitope conservation or escape. We predict greater conservation for epitopes contributing significantly to total immune activation levels (immunodominance), and when TH cell infection is concomitant to epitope recognition (trans-infection). We suggest that HIV-driven immune activation in the lymph nodes during the chronic stage of the disease may offer a favorable scenario for epitope conservation. Our results also support the view that some pathogens draw benefits from the immune response and suggest that vaccination strategies based on conserved TH epitopes may be counterproductive. Note from the author: this version of the model is more general that the one described in the paper. This is because: (i) it can consider simultaneously Th-epitope escape mutants, CTL-epitope escape mutants and full T-cell (Th and CTL) escape mutants, by setting the mutation rate of Th and CTL escape mutants to zero. (ii) It allows for back mutations, which were ignored in all the simulations shown in the paper. (iii) It allows for a fitness cost of escape mutants, which was set to zero in the article. (iv) pAPCs can be infected and produce viruses (the rate of viral production for pAPCs was set to zero in the paper). This model is hosted on BioModels Database and identified by: MODEL1302180001 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Sanjuan2013 - Evolution of HIV T-cell epitope, control model Control model in which the virus targets a nonimmune cell type C (e.g., hepatocytes, epithelial cells, etc.), instead of T H cells. This model is described in the article: Immune activation promotes evolutionary conservation of T-cell epitopes in HIV-1. Sanjuán R, Nebot MR, Peris JB, Alcamí J. PLoS Biol. 2013 Apr;11(4):e1001523 Abstract: The immune system should constitute a strong selective pressure promoting viral genetic diversity and evolution. However, HIV shows lower sequence variability at T-cell epitopes than elsewhere in the genome, in contrast with other human RNA viruses. Here, we propose that epitope conservation is a consequence of the particular interactions established between HIV and the immune system. On one hand, epitope recognition triggers an anti-HIV response mediated by cytotoxic T-lymphocytes (CTLs), but on the other hand, activation of CD4(+) helper T lymphocytes (TH cells) promotes HIV replication. Mathematical modeling of these opposite selective forces revealed that selection at the intrapatient level can promote either T-cell epitope conservation or escape. We predict greater conservation for epitopes contributing significantly to total immune activation levels (immunodominance), and when TH cell infection is concomitant to epitope recognition (trans-infection). We suggest that HIV-driven immune activation in the lymph nodes during the chronic stage of the disease may offer a favorable scenario for epitope conservation. Our results also support the view that some pathogens draw benefits from the immune response and suggest that vaccination strategies based on conserved TH epitopes may be counterproductive. This model is hosted on BioModels Database and identified by: MODEL1302180002 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Next-generation T-cell-directed vaccines for COVID-19 aim to induce durable T-cell immunity against circulating and future hypermutated SARS-CoV-2 variants. Mass Spectrometry (MS)based immunopeptidomics holds promise for guiding vaccine design, but computational challenges impede the precise and unbiased identification of conserved T-cell epitopes crucial for vaccines against rapidly mutating viruses. We introduce a computational framework and analysis platform integrating a novel machine learning algorithm, immunopeptidomics, intra-host data, epitope immunogenicity, and geo-temporal CD8+ T-cell epitope conservation analyses. Central to our approach is MHCvalidator, a novel artificial neural network algorithm enhancing MS-based immunopeptidomics sensitivity by modeling antigen presentation and sequence features. MHCvalidator identified a novel nonconventional SARS-CoV-2 T-cell epitope presented by B7 supertype molecules, originating from a +1-frameshift in a truncated Spike (S) antigen, supported by ribo-seq data. Intra-host analysis of SARS-CoV-2 proteomes from ~100,000 COVID-19 patients revealed a prevalent S antigen truncation in ~51% of cases, exposing a rich source of frameshifted viral antigens. Our framework includes EpiTrack, a new computational pipeline tracking global mutational dynamics of MHCvalidator-identified SARS-CoV-2 CD8+ epitopes from vaccine BNT162b4. While most vaccine-encoded CD8+ epitopes exhibit global conservation from January 2020 to October 2023, a highly immunodominant A*01-associated epitope, especially in hospitalized patients, undergoes substantial mutations in Delta and Omicron variants. Our approach unveils unprecedented SARS-CoV-2 T-cell epitopes, elucidates novel antigenic features, and underscores mutational dynamics of vaccine-relevant epitopes. The analysis platform is applicable to any viruses, and underscores the need for continual vigilance in T-cell vaccine development against the evolving landscape of hypermutating SARS-CoV-2 variants.

Project description:During the course of infection, T cells are confronted with a multitude of non self epitopes but only respond to a few epitopes and neglect other potentially immunogenic peptides. Restriction of T cell responses to a small number of selected epitopes (immunodominance) is a central feature of immune responses. Immunodominance is considered to be disadvantageous to the host because it allows pathogens to escape by selectively mutating the relevant epitope(s). Using Affymetrix microarrays, we compared the gene expression profile of unprimed CD8 T cells to that of effector CD8 T cells specific for a dominant (H7a) and a nondominant (HY) Ag. Our key finding is that T cells specific for the dominant and nondominant Ags displayed similar gene expression profiles except for a few gene transcripts, such as Gzma, Sell, Il7r and Klrg1, that contribute to the fitness of effector CD8 T cells. The differences between HY- and H7a-specific CD8 T cells were validated by real-time PCR and flow cytometry analyses. We propose that, by leading to selective expansion of the fittest CD8 effector T cells, immunodominance may be beneficial to the host. Inhibition of T cell response to nondominant Ags would ensure that host resources (APCs, cytokines) for which T cells compete are devoted to T cells that have the best effector potential. One implication is that, in general, favouring expansion of the fittest effector T cells may be more important that increasing the diversity of the T cell repertoire. Experiment Overall Design: B10.H7b female mice were primed by i.p. injection of a cell mixture containing 2 x 107 B10 male splenocytes and 2 x 107 B10.H7b male splenocytes. On day 14 after priming, splenocytes were labeled with anti-CD8 Ab as well as H7a- and HY-Tet labeled with different fluorochromes. Then, three populations of splenocytes were purified using a FACS cell sorting: HYTet+ (n=4), H7aTet+ (n=4), and Tet- (n=5) CD8 T cells. RNA of sorted T cells was extracted and linearly amplified, cRNA was prepared, and Affymetrix Mouse Genome 430 2.0 oligonucleotide arrays were used to analyze gene expression.

			Action	DRS
	CovidAntigenEpitopeMGF.zip	Other
	DB_search_psm.csv	Csv
	NP16D103N.zip	Other
	NP16D103Y.zip	Other
	NP16WT.zip	Other

Dataset Information

Mutations in epitope flanking regions for SARS-CoV-2 nucleoprotein affect proteasomal processing to alter CD8+ T cell responses

Dataset's files

Publications

SARS-CoV-2 mutations affect antigen processing by the proteasome to alter CD8<sup>+</sup> T cell responses.

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