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1.
PLoS Comput Biol ; 18(2): e1009726, 2022 02.
Article in English | MEDLINE | ID: covidwho-1753172

ABSTRACT

The massive assessment of immune evasion due to viral mutations that increase COVID-19 susceptibility can be computationally facilitated. The adaptive cytotoxic T response is critical during primary infection and the generation of long-term protection. Here, potential HLA class I epitopes in the SARS-CoV-2 proteome were predicted for 2,915 human alleles of 71 families using the netMHCIpan EL algorithm. Allele families showed extreme epitopic differences, underscoring genetic variability of protective capacity between humans. Up to 1,222 epitopes were associated with any of the twelve supertypes, that is, allele clusters covering 90% population. Next, from all mutations identified in ~118,000 viral NCBI isolates, those causing significant epitope score reduction were considered epitope escape mutations. These mutations mainly involved non-conservative substitutions at the second and C-terminal position of the ligand core, or total ligand removal by large recurrent deletions. Escape mutations affected 47% of supertype epitopes, which in 21% of cases concerned isolates from two or more sub-continental areas. Some of these changes were coupled, but never surpassed 15% of evaded epitopes for the same supertype in the same isolate, except for B27. In contrast to most supertypes, eight allele families mostly contained alleles with few SARS-CoV-2 ligands. Isolates harboring cytotoxic escape mutations for these families co-existed geographically within sub-Saharan and Asian populations enriched in these alleles according to the Allele Frequency Net Database. Collectively, our findings indicate that escape mutation events have already occurred for half of HLA class I supertype epitopes. However, it is presently unlikely that, overall, it poses a threat to the global population. In contrast, single and double mutations for susceptible alleles may be associated with viral selective pressure and alarming local outbreaks. The integration of genomic, geographical and immunoinformatic information eases the surveillance of variants potentially affecting the global population, as well as minority subpopulations.


Subject(s)
COVID-19 , Genome, Viral , Immune Evasion , Mutation , SARS-CoV-2 , COVID-19/immunology , COVID-19/virology , Epitopes/genetics , Epitopes/immunology , Gene Frequency , Genome, Viral/genetics , Genome, Viral/immunology , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/immunology , Humans , Immune Evasion/genetics , Immune Evasion/immunology , Mutation/genetics , Mutation/immunology , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Viral Proteins/genetics , Viral Proteins/immunology
2.
J Virol ; 94(13)2020 06 16.
Article in English | MEDLINE | ID: covidwho-1723544

ABSTRACT

Genetic variability across the three major histocompatibility complex (MHC) class I genes (human leukocyte antigen A [HLA-A], -B, and -C genes) may affect susceptibility to and severity of the disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease 2019 (COVID-19). We performed a comprehensive in silico analysis of viral peptide-MHC class I binding affinity across 145 HLA-A, -B, and -C genotypes for all SARS-CoV-2 peptides. We further explored the potential for cross-protective immunity conferred by prior exposure to four common human coronaviruses. The SARS-CoV-2 proteome was successfully sampled and was represented by a diversity of HLA alleles. However, we found that HLA-B*46:01 had the fewest predicted binding peptides for SARS-CoV-2, suggesting that individuals with this allele may be particularly vulnerable to COVID-19, as they were previously shown to be for SARS (M. Lin, H.-T. Tseng, J. A. Trejaut, H.-L. Lee, et al., BMC Med Genet 4:9, 2003, https://bmcmedgenet.biomedcentral.com/articles/10.1186/1471-2350-4-9). Conversely, we found that HLA-B*15:03 showed the greatest capacity to present highly conserved SARS-CoV-2 peptides that are shared among common human coronaviruses, suggesting that it could enable cross-protective T-cell-based immunity. Finally, we reported global distributions of HLA types with potential epidemiological ramifications in the setting of the current pandemic.IMPORTANCE Individual genetic variation may help to explain different immune responses to a virus across a population. In particular, understanding how variation in HLA may affect the course of COVID-19 could help identify individuals at higher risk from the disease. HLA typing can be fast and inexpensive. Pairing HLA typing with COVID-19 testing where feasible could improve assessment of severity of viral disease in the population. Following the development of a vaccine against SARS-CoV-2, the virus that causes COVID-19, individuals with high-risk HLA types could be prioritized for vaccination.


Subject(s)
Betacoronavirus/immunology , Coronavirus Infections/virology , Histocompatibility Testing/methods , Pneumonia, Viral/virology , Amino Acid Sequence , COVID-19 , COVID-19 Testing , Clinical Laboratory Techniques , Coronavirus Infections/diagnosis , Coronavirus Infections/immunology , Epitopes, T-Lymphocyte/immunology , Genetic Variation , Genotype , Haplotypes , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/immunology , Humans , Immunity, Innate/immunology , Pandemics , Pneumonia, Viral/immunology , SARS-CoV-2 , T-Lymphocytes/immunology
3.
Brief Bioinform ; 23(2)2022 03 10.
Article in English | MEDLINE | ID: covidwho-1713564

ABSTRACT

The development of autoimmune diseases following SARS-CoV-2 infection, including multisystem inflammatory syndrome, has been reported, and several mechanisms have been suggested, including molecular mimicry. We developed a scalable, comparative immunoinformatics pipeline called cross-reactive-epitope-search-using-structural-properties-of-proteins (CRESSP) to identify cross-reactive epitopes between a collection of SARS-CoV-2 proteomes and the human proteome using the structural properties of the proteins. Overall, by searching 4 911 245 proteins from 196 352 SARS-CoV-2 genomes, we identified 133 and 648 human proteins harboring potential cross-reactive B-cell and CD8+ T-cell epitopes, respectively. To demonstrate the robustness of our pipeline, we predicted the cross-reactive epitopes of coronavirus spike proteins, which were recognized by known cross-neutralizing antibodies. Using single-cell expression data, we identified PARP14 as a potential target of intermolecular epitope spreading between the virus and human proteins. Finally, we developed a web application (https://ahs2202.github.io/3M/) to interactively visualize our results. We also made our pipeline available as an open-source CRESSP package (https://pypi.org/project/cressp/), which can analyze any two proteomes of interest to identify potentially cross-reactive epitopes between the proteomes. Overall, our immunoinformatic resources provide a foundation for the investigation of molecular mimicry in the pathogenesis of autoimmune and chronic inflammatory diseases following COVID-19.


Subject(s)
Computational Biology/methods , Epitopes/chemistry , Epitopes/immunology , SARS-CoV-2/immunology , Software , Viral Proteins/chemistry , Viral Proteins/immunology , Algorithms , Cross Reactions/immunology , Epitopes, B-Lymphocyte , Epitopes, T-Lymphocyte , Histocompatibility Antigens Class I/chemistry , Histocompatibility Antigens Class I/immunology , Histocompatibility Antigens Class II/chemistry , Histocompatibility Antigens Class II/immunology , Models, Molecular , Molecular Mimicry , Neural Networks, Computer , Proteome , Proteomics/methods , Structure-Activity Relationship , Web Browser
4.
Cell Rep ; 38(10): 110503, 2022 03 08.
Article in English | MEDLINE | ID: covidwho-1705992

ABSTRACT

Natural killer (NK) cells are innate immune cells that contribute to host defense against virus infections. NK cells respond to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro and are activated in patients with acute coronavirus disease 2019 (COVID-19). However, by which mechanisms NK cells detect SARS-CoV-2-infected cells remains largely unknown. Here, we show that the Non-structural protein 13 of SARS-CoV-2 encodes for a peptide that is presented by human leukocyte antigen E (HLA-E). In contrast with self-peptides, the viral peptide prevents binding of HLA-E to the inhibitory receptor NKG2A, thereby rendering target cells susceptible to NK cell attack. In line with these observations, NKG2A-expressing NK cells are particularly activated in patients with COVID-19 and proficiently limit SARS-CoV-2 replication in infected lung epithelial cells in vitro. Thus, these data suggest that a viral peptide presented by HLA-E abrogates inhibition of NKG2A+ NK cells, resulting in missing self-recognition.


Subject(s)
COVID-19 , Histocompatibility Antigens Class I , Killer Cells, Natural , Methyltransferases , NK Cell Lectin-Like Receptor Subfamily C , RNA Helicases , SARS-CoV-2 , Viral Nonstructural Proteins , COVID-19/immunology , Histocompatibility Antigens Class I/immunology , Humans , Killer Cells, Natural/immunology , Methyltransferases/immunology , NK Cell Lectin-Like Receptor Subfamily C/immunology , NK Cell Lectin-Like Receptor Subfamily C/metabolism , Peptides/metabolism , RNA Helicases/immunology , Viral Nonstructural Proteins/immunology
5.
Front Immunol ; 13: 832889, 2022.
Article in English | MEDLINE | ID: covidwho-1686488

ABSTRACT

The potential effect of emerging SARS-CoV-2 variants on vaccine efficacy is an issue of critical importance. In this study, the possible impact of mutations that facilitate virus escape from the cytotoxic and the helper cellular immune responses in the new SARS-CoV-2 Omicron variant of concern was analyzed for the 551 and 41 most abundant HLA class I and II alleles, respectively. Computational prediction showed that almost all of these 592 alleles, which cover >90% of the human population, contain enough epitopes without escape mutations in the emerging SARS-CoV-2 Omicron variant of concern. These data suggest that both cytotoxic and helper cellular immune protection elicited by currently licensed vaccines are virtually unaffected by the highly contagious SARS-CoV-2 Omicron variant of concern.


Subject(s)
COVID-19/immunology , Histocompatibility Antigens Class II/immunology , Histocompatibility Antigens Class I/immunology , Immunity, Cellular/immunology , SARS-CoV-2/immunology , Epitopes, T-Lymphocyte/immunology , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class II/genetics , Humans , Immunogenicity, Vaccine/immunology , Mutation , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology
6.
Rev Med Virol ; 31(6): e2236, 2021 11.
Article in English | MEDLINE | ID: covidwho-1573896

ABSTRACT

Modifications in HLA-I expression are found in many viral diseases. They represent one of the immune evasion strategies most widely used by viruses to block antigen presentation and NK cell response, and SARS-CoV-2 is no exception. These alterations result from a combination of virus-specific factors, genetically encoded mechanisms, and the status of host defences and range from loss or upregulation of HLA-I molecules to selective increases of HLA-I alleles. In this review, I will first analyse characteristic features of altered HLA-I expression found in SARS-CoV-2. I will then discuss the potential factors underlying these defects, focussing on HLA-E and class-I-related (like) molecules and their receptors, the most documented HLA-I alterations. I will also draw attention to potential differences between cells transfected to express viral proteins and those presented as part of authentic infection. Consideration of these factors and others affecting HLA-I expression may provide us with improved possibilities for research into cellular immunity against viral variants.


Subject(s)
Antigenic Variation , COVID-19/immunology , Clonal Anergy , Histocompatibility Antigens Class I/immunology , Immune Evasion , SARS-CoV-2/genetics , Alleles , COVID-19/pathology , COVID-19/virology , Cytokines/genetics , Cytokines/immunology , Cytotoxicity, Immunologic , Gene Expression , Histocompatibility Antigens Class I/genetics , Humans , Immunity, Cellular , Killer Cells, Natural/immunology , Killer Cells, Natural/virology , NK Cell Lectin-Like Receptor Subfamily C/genetics , NK Cell Lectin-Like Receptor Subfamily C/immunology , NK Cell Lectin-Like Receptor Subfamily D/genetics , NK Cell Lectin-Like Receptor Subfamily D/immunology , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , T-Lymphocytes, Cytotoxic/immunology , T-Lymphocytes, Cytotoxic/virology
7.
Ann Rheum Dis ; 80(12): 1537-1544, 2021 12.
Article in English | MEDLINE | ID: covidwho-1515258

ABSTRACT

OBJECTIVES: The monoclonal anti-CD20 antibody rituximab is frequently applied in the treatment of lymphoma as well as autoimmune diseases and confers efficient depletion of recirculating B cells. Correspondingly, B cell-depleted patients barely mount de novo antibody responses during infections or vaccinations. Therefore, efficient immune responses of B cell-depleted patients largely depend on protective T cell responses. METHODS: CD8+ T cell expansion was studied in rituximab-treated rheumatoid arthritis (RA) patients and B cell-deficient mice on vaccination/infection with different vaccines/pathogens. RESULTS: Rituximab-treated RA patients vaccinated with Influvac showed reduced expansion of influenza-specific CD8+ T cells when compared with healthy controls. Moreover, B cell-deficient JHT mice infected with mouse-adapted Influenza or modified vaccinia virus Ankara showed less vigorous expansion of virus-specific CD8+ T cells than wild type mice. Of note, JHT mice do not have an intrinsic impairment of CD8+ T cell expansion, since infection with vaccinia virus induced similar T cell expansion in JHT and wild type mice. Direct type I interferon receptor signalling of B cells was necessary to induce several chemokines in B cells and to support T cell help by enhancing the expression of MHC-I. CONCLUSIONS: Depending on the stimulus, B cells can modulate CD8+ T cell responses. Thus, B cell depletion causes a deficiency of de novo antibody responses and affects the efficacy of cellular response including cytotoxic T cells. The choice of the appropriate vaccine to vaccinate B cell-depleted patients has to be re-evaluated in order to efficiently induce protective CD8+ T cell responses.


Subject(s)
Antirheumatic Agents/adverse effects , Arthritis, Rheumatoid/drug therapy , B-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Immunogenicity, Vaccine/immunology , Influenza Vaccines/immunology , Interferon Type I/immunology , Rituximab/adverse effects , Animals , Case-Control Studies , Cytokines/immunology , Histocompatibility Antigens Class I/immunology , Humans , Influenza Vaccines/therapeutic use , Influenza, Human/prevention & control , Mice , Orthomyxoviridae/immunology , Orthomyxoviridae Infections/immunology , Vaccinia/immunology , Vaccinia virus/immunology
8.
J Med Virol ; 93(9): 5350-5357, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1384240

ABSTRACT

PARP14 and PARP9 play a key role in macrophage immune regulation. SARS-CoV-2 is an emerging viral disease that triggers hyper-inflammation known as a cytokine storm. In this study, using in silico tools, we hypothesize about the immunological phenomena of molecular mimicry between SARS-CoV-2 Nsp3 and the human PARP14 and PARP9. The results showed an epitope of SARS-CoV-2 Nsp3 protein that contains consensus sequences for both human PARP14 and PARP9 that are antigens for MHC Classes 1 and 2, which can potentially induce an immune response against human PARP14 and PARP9; while its depletion causes a hyper-inflammatory state in SARS-CoV-2 patients.


Subject(s)
COVID-19/immunology , Coronavirus Papain-Like Proteases/chemistry , Cytokine Release Syndrome/immunology , Neoplasm Proteins/chemistry , Poly(ADP-ribose) Polymerases/chemistry , SARS-CoV-2/immunology , Amino Acid Sequence , Binding Sites , COVID-19/genetics , COVID-19/pathology , COVID-19/virology , Computer Simulation , Consensus Sequence , Coronavirus Papain-Like Proteases/genetics , Coronavirus Papain-Like Proteases/immunology , Cytokine Release Syndrome/genetics , Cytokine Release Syndrome/pathology , Cytokine Release Syndrome/virology , Epitopes/chemistry , Epitopes/genetics , Epitopes/immunology , Gene Expression , Histocompatibility Antigens Class I/chemistry , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/immunology , Histocompatibility Antigens Class II/chemistry , Histocompatibility Antigens Class II/genetics , Histocompatibility Antigens Class II/immunology , Host-Pathogen Interactions/genetics , Host-Pathogen Interactions/immunology , Humans , Macrophages/immunology , Macrophages/virology , Molecular Docking Simulation , Molecular Mimicry , Neoplasm Proteins/genetics , Neoplasm Proteins/immunology , Poly(ADP-ribose) Polymerases/genetics , Poly(ADP-ribose) Polymerases/immunology , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Sequence Alignment , Sequence Homology, Amino Acid , Thermodynamics
9.
Int J Mol Sci ; 22(6)2021 Mar 17.
Article in English | MEDLINE | ID: covidwho-1389395

ABSTRACT

As an essential modulator of IgG disposition, the neonatal Fc receptor (FcRn) governs the pharmacokinetics and functions many therapeutic modalities. In this review, we thoroughly reexamine the hitherto elucidated biological and thermodynamic properties of FcRn to provide context for our assessment of more recent advances, which covers antigen-binding fragment (Fab) determinants of FcRn affinity, transgenic preclinical models, and FcRn targeting as an immune-complex (IC)-clearing strategy. We further comment on therapeutic antibodies authorized for treating SARS-CoV-2 (bamlanivimab, casirivimab, and imdevimab) and evaluate their potential to saturate FcRn-mediated recycling. Finally, we discuss modeling and simulation studies that probe the quantitative relationship between in vivo IgG persistence and in vitro FcRn binding, emphasizing the importance of endosomal transit parameters.


Subject(s)
Histocompatibility Antigens Class I/chemistry , Histocompatibility Antigens Class I/metabolism , Receptors, Fc/chemistry , Receptors, Fc/metabolism , Animals , Antibodies, Monoclonal/metabolism , Antibodies, Monoclonal/pharmacokinetics , COVID-19/drug therapy , Histocompatibility Antigens Class I/immunology , Humans , Immunoglobulin G/immunology , Immunoglobulin G/metabolism , Receptors, Fc/immunology , Tissue Distribution/immunology
10.
Front Immunol ; 11: 605688, 2020.
Article in English | MEDLINE | ID: covidwho-1389170

ABSTRACT

Aim: SARS-CoV-2 infection is a world-wide public health problem. Several aspects of its pathogenesis and the related clinical consequences still need elucidation. In Italy, Sardinia has had very low numbers of infections. Taking advantage of the low genetic polymorphism in the Sardinian population, we analyzed clinical, genetic and immunogenetic factors, with particular attention to HLA class I and II molecules, to evaluate their influence on susceptibility to SARS-CoV-2 infection and the clinical outcome. Method and Materials: We recruited 619 healthy Sardinian controls and 182 SARS-CoV-2 patients. Thirty-nine patients required hospital care and 143 were without symptoms, pauci-symptomatic or with mild disease. For all participants, we collected demographic and clinical data and analyzed the HLA allele and haplotype frequencies. Results: Male sex and older age were more frequent in hospitalized patients, none of whom had been vaccinated during the previous seasonal flu vaccination campaignes. Compared to the group of asymptomatic or pauci-symptomatic patients, hospitalized patients also had a higher frequency of autoimmune diseases and glucose-6-phosphate-dehydrogenase (G6PDH) deficiency. None of these patients carried the beta-thalassemia trait, a relatively common finding in the Sardinian population. The extended haplotype HLA-A*02:05, B*58:01, C*07:01, DRB1*03:01 [OR 0.1 (95% CI 0-0.6), Pc = 0.015] was absent in all 182 patients, while the HLA-C*04:01 allele and the three-loci haplotype HLA-A*30:02, B*14:02, C*08:02 [OR 3.8 (95% CI 1.8-8.1), Pc = 0.025] were more frequently represented in patients than controls. In a comparison between in-patients and home care patients, the HLA-DRB1*08:01 allele was exclusively present in the hospitalized patients [OR > 2.5 (95% CI 2.7-220.6), Pc = 0.024]. Conclusion: The data emerging from our study suggest that the extended haplotype HLA-A*02:05, B*58:01, C*07:01, DRB1*03:01 has a protective effect against SARS-CoV-2 infection in the Sardinian population. Genetic factors that resulted to have a negative influence on the disease course were presence of the HLA-DRB1*08:01 allele and G6PDH deficiency, but not the beta-thalassemic trait. Absence of influenza vaccination could be a predisposing factor for more severe disease.


Subject(s)
COVID-19 , Gene Frequency , Genetic Predisposition to Disease , HLA-DRB1 Chains , Histocompatibility Antigens Class I , SARS-CoV-2/immunology , Adult , Aged , COVID-19/genetics , COVID-19/immunology , COVID-19/pathology , Female , HLA-DRB1 Chains/genetics , HLA-DRB1 Chains/immunology , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/immunology , Humans , Immunogenetics , Italy , Male , Middle Aged , Severity of Illness Index
11.
Front Immunol ; 11: 1836, 2020.
Article in English | MEDLINE | ID: covidwho-1389162

ABSTRACT

Examining CD8+ and CD4+ T cell responses after primary Yellow Fever vaccination in a cohort of 210 volunteers, we have identified and tetramer-validated 92 CD8+ and 50 CD4+ T cell epitopes, many inducing strong and prevalent (i.e., immunodominant) T cell responses. Restricted by 40 and 14 HLA-class I and II allotypes, respectively, these responses have wide population coverage and might be of considerable academic, diagnostic and therapeutic interest. The broad coverage of epitopes and HLA overcame the otherwise confounding effects of HLA diversity and non-HLA background providing the first evidence of T cell immunodomination in humans. Also, double-staining of CD4+ T cells with tetramers representing the same HLA-binding core, albeit with different flanking regions, demonstrated an extensive diversification of the specificities of many CD4+ T cell responses. We suggest that this could reduce the risk of pathogen escape, and that multi-tetramer staining is required to reveal the true magnitude and diversity of CD4+ T cell responses. Our T cell epitope discovery approach uses a combination of (1) overlapping peptides representing the entire Yellow Fever virus proteome to search for peptides containing CD4+ and/or CD8+ T cell epitopes, (2) predictors of peptide-HLA binding to suggest epitopes and their restricting HLA allotypes, (3) generation of peptide-HLA tetramers to identify T cell epitopes, and (4) analysis of ex vivo T cell responses to validate the same. This approach is systematic, exhaustive, and can be done in any individual of any HLA haplotype. It is all-inclusive in the sense that it includes all protein antigens and peptide epitopes, and encompasses both CD4+ and CD8+ T cell epitopes. It is efficient and, importantly, reduces the false discovery rate. The unbiased nature of the T cell epitope discovery approach presented here should support the refinement of future peptide-HLA class I and II predictors and tetramer technologies, which eventually should cover all HLA class I and II isotypes. We believe that future investigations of emerging pathogens (e.g., SARS-CoV-2) should include population-wide T cell epitope discovery using blood samples from patients, convalescents and/or long-term survivors, who might all hold important information on T cell epitopes and responses.


Subject(s)
CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Epitopes, T-Lymphocyte/immunology , Vaccination , Yellow Fever Vaccine/immunology , Yellow Fever/prevention & control , Yellow fever virus/immunology , Betacoronavirus/immunology , COVID-19 , Cohort Studies , Coronavirus Infections/prevention & control , Coronavirus Infections/virology , Healthy Volunteers , Histocompatibility Antigens Class I/immunology , Histocompatibility Antigens Class II/immunology , Humans , Immunogenicity, Vaccine , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Pneumonia, Viral/virology , SARS-CoV-2 , Yellow Fever/virology
12.
Sci Rep ; 11(1): 17234, 2021 08 26.
Article in English | MEDLINE | ID: covidwho-1376209

ABSTRACT

Over the past two decades, there has been a great interest in the study of HLA-E-restricted αß T cells during bacterial and viral infections, including recently SARS-CoV-2 infection. Phenotyping of these specific HLA-E-restricted T cells requires new tools such as tetramers for rapid cell staining or sorting, as well as for the identification of new peptides capable to bind to the HLA-E pocket. To this aim, we have developed an optimal photosensitive peptide to generate stable HLA-E/pUV complexes allowing high-throughput production of new HLA-E/peptide complexes by peptide exchange. We characterized the UV exchange by ELISA and improved the peptide exchange readout using size exclusion chromatography. This novel approach for complex quantification is indeed very important to perform tetramerization of MHC/peptide complexes with the high quality required for detection of specific T cells. Our approach allows the rapid screening of peptides capable of binding to the non-classical human HLA-E allele, paving the way for the development of new therapeutic approaches based on the detection of HLA-E-restricted T cells.


Subject(s)
Epitopes, T-Lymphocyte/chemistry , Histocompatibility Antigens Class I/chemistry , Major Histocompatibility Complex/immunology , Peptides/chemistry , Amino Acid Sequence , Epitopes, T-Lymphocyte/immunology , High-Throughput Screening Assays , Histocompatibility Antigens Class I/immunology , Humans , Immunologic Techniques , Photochemical Processes , Protein Binding , Protein Conformation , T-Lymphocytes, Cytotoxic/immunology
13.
Front Immunol ; 12: 698193, 2021.
Article in English | MEDLINE | ID: covidwho-1354865

ABSTRACT

HLA molecules are key restrictive elements to present intracellular antigens at the crossroads of an effective T-cell response against SARS-CoV-2. To determine the impact of the HLA genotype on the severity of SARS-CoV-2 courses, we investigated data from 6,919 infected individuals. HLA-A, -B, and -DRB1 allotypes grouped into HLA supertypes by functional or predicted structural similarities of the peptide-binding grooves did not predict COVID-19 severity. Further, we did not observe a heterozygote advantage or a benefit from HLA diplotypes with more divergent physicochemical peptide-binding properties. Finally, numbers of in silico predicted viral T-cell epitopes did not correlate with the severity of SARS-CoV-2 infections. These findings suggest that the HLA genotype is no major factor determining COVID-19 severity. Moreover, our data suggest that the spike glycoprotein alone may allow for abundant T-cell epitopes to mount robust T-cell responses not limited by the HLA genotype.


Subject(s)
Coronavirus Infections/genetics , Histocompatibility Antigens Class II/immunology , Histocompatibility Antigens Class I/immunology , Adult , Computer Simulation , Cross-Sectional Studies , Epitopes, T-Lymphocyte/genetics , Epitopes, T-Lymphocyte/immunology , Female , Genotype , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class II/genetics , Humans , Male , Middle Aged , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/immunology
14.
J Clin Pathol ; 74(8): 528-532, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1318062

ABSTRACT

AIMS: Brazil is nowadays one of the epicentres of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and new therapies are needed to face it. In the context of specific immune response against the virus, a correlation between Major Histocompatibility Complex Class I (MHC-I) and the severity of the disease in patients with COVID-19 has been suggested. Aiming at better understanding the biology of the infection and the immune response against the virus in the Brazilian population, we analysed SARS-CoV-2 protein S peptides in order to identify epitopes able to elicit an immune response mediated by the most frequent MHC-I alleles using in silico methods. METHODS: Our analyses consisted in searching for the most frequent Human Leukocyte Antigen (HLA)-A, HLA-B and HLA-C alleles in the Brazilian population, excluding the genetic isolates; then, we performed: molecular modelling for unsolved structures, MHC-I binding affinity and antigenicity prediction, peptide docking and molecular dynamics of the best fitted MHC-I/protein S complexes. RESULTS: We identified 24 immunogenic epitopes in the SARS-CoV-2 protein S that could interact with 17 different MHC-I alleles (namely, HLA-A*01:01; HLA-A*02:01; HLA-A*11:01; HLA-A*24:02; HLA-A*68:01; HLA-A*23:01; HLA-A*26:01; HLA-A*30:02; HLA-A*31:01; HLA-B*07:02; HLA-B*51:01; HLA-B*35:01; HLA-B*44:02; HLA-B*35:03; HLA-C*05:01; HLA-C*07:01 and HLA-C*15:02) in the Brazilian population. CONCLUSIONS: Being aware of the intrinsic limitations of in silico analysis (mainly the differences between the real and the Protein Data Bank (PDB) structure; and accuracy of the methods for simulate proteasome cleavage), we identified 24 epitopes able to interact with 17 MHC-I more frequent alleles in the Brazilian population that could be useful for the development of strategic methods for vaccines against SARS-CoV-2.


Subject(s)
Epitope Mapping , Epitopes , HLA Antigens/immunology , Histocompatibility Antigens Class I/immunology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Brazil , Gene Frequency , HLA Antigens/genetics , Histocompatibility Antigens Class I/genetics , Host-Pathogen Interactions , Humans , Molecular Docking Simulation , Molecular Dynamics Simulation , Protein Binding , Protein Conformation , SARS-CoV-2/pathogenicity
15.
Int J Mol Sci ; 22(13)2021 Jun 22.
Article in English | MEDLINE | ID: covidwho-1304657

ABSTRACT

The innate immune system's natural killer (NK) cells exert their cytolytic function against a variety of pathological challenges, including tumors and virally infected cells. Their activation depends on net signaling mediated via inhibitory and activating receptors that interact with specific ligands displayed on the surfaces of target cells. The CD94/NKG2C heterodimer is one of the NK activating receptors and performs its function by interacting with the trimeric ligand comprised of the HLA-E/ß2m/nonameric peptide complex. Here, simulations of the all-atom multi-microsecond molecular dynamics in five immune complexes provide atomistic insights into the receptor-ligand molecular recognition, as well as the molecular events that facilitate the NK cell activation. We identify NKG2C, the HLA-Eα2 domain, and the nonameric peptide as the key elements involved in the molecular machinery of signal transduction via an intertwined hydrogen bond network. Overall, the study addresses the complex intricacies that are necessary to understand the mechanisms of the innate immune system.


Subject(s)
Antigen-Antibody Complex/chemistry , Histocompatibility Antigens Class I/chemistry , Models, Molecular , NK Cell Lectin-Like Receptor Subfamily C/chemistry , NK Cell Lectin-Like Receptor Subfamily D/chemistry , Peptides/chemistry , Amino Acid Sequence , Antigen-Antibody Complex/immunology , Antigen-Antibody Complex/metabolism , Binding Sites , Histocompatibility Antigens Class I/immunology , Histocompatibility Antigens Class I/metabolism , Humans , Hydrogen Bonding , Ligands , NK Cell Lectin-Like Receptor Subfamily C/metabolism , NK Cell Lectin-Like Receptor Subfamily D/metabolism , Peptides/metabolism , Protein Binding , Protein Conformation , Protein Interaction Domains and Motifs , Signal Transduction , Structure-Activity Relationship
16.
Viruses ; 13(7)2021 06 27.
Article in English | MEDLINE | ID: covidwho-1289026

ABSTRACT

Many viruses, especially RNA viruses, utilize programmed ribosomal frameshifting and/or stop codon readthrough in their expression, and in the decoding of a few a UGA is dynamically redefined to specify selenocysteine. This recoding can effectively increase viral coding capacity and generate a set ratio of products with the same N-terminal domain(s) but different C-terminal domains. Recoding can also be regulatory or generate a product with the non-universal 21st directly encoded amino acid. Selection for translation speed in the expression of many viruses at the expense of fidelity creates host immune defensive opportunities. In contrast to host opportunism, certain viruses, including some persistent viruses, utilize recoding or adventitious frameshifting as part of their strategy to evade an immune response or specific drugs. Several instances of recoding in small intensively studied viruses escaped detection for many years and their identification resolved dilemmas. The fundamental importance of ribosome ratcheting is consistent with the initial strong view of invariant triplet decoding which however did not foresee the possibility of transitory anticodon:codon dissociation. Deep level dynamics and structural understanding of recoding is underway, and a high level structure relevant to the frameshifting required for expression of the SARS CoV-2 genome has just been determined.


Subject(s)
DNA Viruses/genetics , DNA Viruses/immunology , Histocompatibility Antigens Class I/immunology , Immune Evasion , RNA Viruses/genetics , Antiviral Agents/pharmacology , Codon, Terminator , DNA Viruses/drug effects , Frameshifting, Ribosomal , Histocompatibility Antigens Class I/genetics , Nucleic Acid Conformation , Peptides/immunology , Protein Biosynthesis , RNA Viruses/drug effects , RNA Viruses/immunology
17.
Cell Rep ; 35(13): 109305, 2021 06 29.
Article in English | MEDLINE | ID: covidwho-1260679

ABSTRACT

The human leukocyte antigen (HLA)-bound viral antigens serve as an immunological signature that can be selectively recognized by T cells. As viruses evolve by acquiring mutations, it is essential to identify a range of presented viral antigens. Using HLA peptidomics, we are able to identify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-derived peptides presented by highly prevalent HLA class I (HLA-I) molecules by using infected cells as well as overexpression of SARS-CoV-2 genes. We find 26 HLA-I peptides and 36 HLA class II (HLA-II) peptides. Among the identified peptides, some are shared between different cells and some are derived from out-of-frame open reading frames (ORFs). Seven of these peptides were previously shown to be immunogenic, and we identify two additional immunoreactive peptides by using HLA multimer staining. These results may aid the development of the next generation of SARS-CoV-2 vaccines based on presented viral-specific antigens that span several of the viral genes.


Subject(s)
Antigens, Viral/immunology , COVID-19/immunology , COVID-19/virology , Peptides/immunology , SARS-CoV-2/immunology , Antigen Presentation , Antigens, Viral/metabolism , COVID-19 Vaccines , Cell Line , Epitopes, T-Lymphocyte/immunology , HEK293 Cells , Histocompatibility Antigens Class I/immunology , Histocompatibility Antigens Class II/immunology , Humans , Peptidomimetics , SARS-CoV-2/genetics , T-Lymphocytes
18.
Cell ; 184(15): 3962-3980.e17, 2021 07 22.
Article in English | MEDLINE | ID: covidwho-1252549

ABSTRACT

T cell-mediated immunity plays an important role in controlling SARS-CoV-2 infection, but the repertoire of naturally processed and presented viral epitopes on class I human leukocyte antigen (HLA-I) remains uncharacterized. Here, we report the first HLA-I immunopeptidome of SARS-CoV-2 in two cell lines at different times post infection using mass spectrometry. We found HLA-I peptides derived not only from canonical open reading frames (ORFs) but also from internal out-of-frame ORFs in spike and nucleocapsid not captured by current vaccines. Some peptides from out-of-frame ORFs elicited T cell responses in a humanized mouse model and individuals with COVID-19 that exceeded responses to canonical peptides, including some of the strongest epitopes reported to date. Whole-proteome analysis of infected cells revealed that early expressed viral proteins contribute more to HLA-I presentation and immunogenicity. These biological insights, as well as the discovery of out-of-frame ORF epitopes, will facilitate selection of peptides for immune monitoring and vaccine development.


Subject(s)
Epitopes, T-Lymphocyte/immunology , Histocompatibility Antigens Class I/immunology , Open Reading Frames/genetics , Peptides/immunology , Proteome/immunology , SARS-CoV-2/immunology , A549 Cells , Alleles , Amino Acid Sequence , Animals , Antigen Presentation/immunology , COVID-19/immunology , COVID-19/virology , Female , HEK293 Cells , Humans , Kinetics , Male , Mice , Peptides/chemistry , T-Lymphocytes/immunology
19.
Proc Natl Acad Sci U S A ; 118(23)2021 06 08.
Article in English | MEDLINE | ID: covidwho-1238060

ABSTRACT

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global pandemic and has claimed over 2 million lives worldwide. Although the genetic sequences of SARS-CoV and SARS-CoV-2 have high homology, the clinical and pathological characteristics of COVID-19 differ significantly from those of SARS. How and whether SARS-CoV-2 evades (cellular) immune surveillance requires further elucidation. In this study, we show that SARS-CoV-2 infection leads to major histocompability complex class Ι (MHC-Ι) down-regulation both in vitro and in vivo. The viral protein encoded by open reading frame 8 (ORF8) of SARS-CoV-2, which shares the least homology with SARS-CoV among all viral proteins, directly interacts with MHC-Ι molecules and mediates their down-regulation. In ORF8-expressing cells, MHC-Ι molecules are selectively targeted for lysosomal degradation via autophagy. Thus, SARS-CoV-2-infected cells are much less sensitive to lysis by cytotoxic T lymphocytes. Because ORF8 protein impairs the antigen presentation system, inhibition of ORF8 could be a strategy to improve immune surveillance.


Subject(s)
Antigen Presentation , COVID-19/immunology , Down-Regulation/immunology , Histocompatibility Antigens Class I/immunology , Immune Evasion , SARS-CoV-2/immunology , Viral Proteins/immunology , Animals , Autophagy/genetics , Autophagy/immunology , COVID-19/genetics , Chlorocebus aethiops , HEK293 Cells , Histocompatibility Antigens Class I/genetics , Humans , Lysosomes/genetics , Lysosomes/immunology , Lysosomes/virology , Mice , Mice, Transgenic , SARS-CoV-2/genetics , Vero Cells , Viral Proteins/genetics
20.
Nat Commun ; 12(1): 2593, 2021 05 10.
Article in English | MEDLINE | ID: covidwho-1223090

ABSTRACT

The COVID-19 pandemic caused by SARS-CoV-2 is a continuous challenge worldwide, and there is an urgent need to map the landscape of immunogenic and immunodominant epitopes recognized by CD8+ T cells. Here, we analyze samples from 31 patients with COVID-19 for CD8+ T cell recognition of 500 peptide-HLA class I complexes, restricted by 10 common HLA alleles. We identify 18 CD8+ T cell recognized SARS-CoV-2 epitopes, including an epitope with immunodominant features derived from ORF1ab and restricted by HLA-A*01:01. In-depth characterization of SARS-CoV-2-specific CD8+ T cell responses of patients with acute critical and severe disease reveals high expression of NKG2A, lack of cytokine production and a gene expression profile inhibiting T cell re-activation and migration while sustaining survival. SARS-CoV-2-specific CD8+ T cell responses are detectable up to 5 months after recovery from critical and severe disease, and these responses convert from dysfunctional effector to functional memory CD8+ T cells during convalescence.


Subject(s)
CD8-Positive T-Lymphocytes/immunology , COVID-19/immunology , Immunodominant Epitopes/immunology , SARS-CoV-2/immunology , Adult , Aged , Aged, 80 and over , Alleles , CD8-Positive T-Lymphocytes/pathology , COVID-19/pathology , Epitopes, T-Lymphocyte/immunology , Female , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/immunology , Humans , Immunodominant Epitopes/chemistry , Immunologic Memory , Lymphocyte Activation , Male , Middle Aged , Polyproteins/immunology , Viral Proteins/immunology
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