The Immune Epitope Database (IEDB): A resource for immunological data related to infectious disease, autoimmunity and allergy. (P3024)

The adaptive immune system in vertebrates has evolved to recognize an immense number of pathogens. B and T cells play important role in the antigen recognition by expressing a substantially diverse repertoire of antigen-specific receptors. The recent advances in the high-throughput immune repertoire sequencing has led to a tremendous increase in the antibody and T-cell receptor information. Identification of specific epitopes recognized by the receptors is vital in analyzing the repertoire sequencing data. Here, we present a tool that examines data from an immune receptor repertoire experiment, and identifies receptors (or highly related variants) that are present in the Immune Epitope Database (IEDB). The IEDB is a free resource which compiles experiments characterizing immune epitopes. IEDB also captures the epitope-specific immune receptor sequences and groups them based on their epitope specificity. IEDB currently has information on over 26,000 receptor groups. Users can provide receptor repertoire sequence data in multiple formats, and specify different CDR sequence identity cutoffs to restrict or broaden the receptor search. We expect that this tool will provide new insights into B and T cell responses captured in the receptor repertoire experiments by identifying specific epitopes, and facilitate development of new strategies for monitoring and treating of infectious, allergic and autoimmune diseases.

BackgroundThere is presently no effective and safe vaccine for Toxoplasma gondii for humans. The study described here was designed to search for a novel group of optimal B cell and T cell epitopes from Toxoplasma membrane proteins using genome-wide comprehensive screening.MethodsThe amino acid sequences of membrane proteins of T. gondii were obtained from the UniProt database. The ABCPred and BepiPred servers were employed to predict the linear B cell epitopes. The Immune Epitope Database (IEDB) online service was utilized to forecast T cell epitopes within T. gondii membrane proteins that bind to human leukocyte antigen (HLA) class I (HLA-I) or HLA-II molecules.ResultsFrom the 314 membrane proteins of T. gondii, a total of 14 linear B cell epitopes embedded in 12 membrane proteins were identified. Eight epitopes for major histocompatibility complex (MHC) class I (MHC-I) molecules and 18 epitopes for MHC-II molecules were ultimately selected, for which world population coverage percentiles were 71.94% and 99.76%, respectively. The top rated combinations of linear B cell epitopes and T cell epitopes covering both BALB/c mice and a majority of the human population were identified for the development of a protective vaccine.ConclusionsThe ultimate vaccine construct described here, which comprises B cells, MHC-I and MHC-II epitopes, might protect individuals against T. gondii infection by inducing humoral and cellular immune responses.Graphic abstract

The adaptive immune system in vertebrates has evolved to recognize non-self antigens, such as proteins expressed by infectious agents and mutated cancer cells. T cells play an important role in antigen recognition by expressing a diverse repertoire of antigen-specific receptors, which bind epitopes to mount targeted immune responses. Recent advances in high-throughput sequencing have enabled the routine generation of T-cell receptor (TCR) repertoire data. Identifying the specific epitopes targeted by different TCRs in these data would be valuable. To accomplish that, we took advantage of the ever-increasing number of TCRs with known epitope specificity curated in the Immune Epitope Database (IEDB) since 2004. We compared seven metrics of sequence similarity to determine their power to predict if two TCRs have the same epitope specificity. We found that a comprehensive k-mer matching approach produced the best results, which we have implemented into TCRMatch, an openly accessible tool (http://tools.iedb.org/tcrmatch/) that takes TCR β-chain CDR3 sequences as an input, identifies TCRs with a match in the IEDB, and reports the specificity of each match. We anticipate that this tool will provide new insights into T cell responses captured in receptor repertoire and single cell sequencing experiments and will facilitate the development of new strategies for monitoring and treatment of infectious, allergic, and autoimmune diseases, as well as cancer.

Mining Immune Epitopes in Ménière’s Disease and Sudden Sensorineural Hearing Loss

Background and Hypothesis:Coxsackievirus B3 (CVB3) is a non-enveloped RNA virus from the Picornaviridae family and is a primary cause of viral myocarditis in the United States. Approximately 5% of all symptomatic CVB3 infections are fatal. Therefore, there is a need to identify the mechanism(s) that regulate a protective immune response to CVB3. However, viral epitopes that stimulate T cell responses to CVB3 remain poorly characterized. To this end, we used a mouse model of CVB3 infection to identify the viral immunogenic CD8 T cell epitopes. We hypothesized that isolated antigen-experienced CD8 T cells from infected mice would be stimulated in the presence of predicted viral epitopes, confirming CVB3-specific T cells. Experimental Design: To identify novel CD8 T cell epitopes, predicted 9-mer MHC binding peptides from the CVB3-Nancy polyprotein were identified using the Immune Epitope Database (IEDB) analysis resource consensus tool. The top ten predicted peptides were synthesized for our assays. Splenocytes from CVB3-infected male and female IFNAR -/- mice were stimulated with each peptide in the presence of brefeldin A for 6 hours at 37˚C. Following stimulation, cells were surfaced stained with antibodies specific for antigen-experienced CD8 T cells. Next, we performed intracellular staining for IFN-gamma. Cells were analyzed using flow cytometry. Candidate epitopes were identified as having results ≥2 standard deviations over the control. Results: Thus far, our analysis has revealed responses to three novel CD8 T cell epitopes within the peptide library, including the viral epitopes within VP1 protein and the RNA-dependent RNA polymerase. Conclusion and Potential ImpactOverall, these data provide an advancement in CVB3 immunology. Further, these data generate new tools like MHC-tetramers to track endogenous T cell responses to CVB3 infection.

IEDB-3D is the 3D structural component of the Immune Epitope Database (IEDB) available via the ‘Browse by 3D Structure’ page at http://www.iedb.org. IEDB-3D catalogs B- and T-cell epitopes and Major Histocompatibility Complex (MHC) ligands for which 3D structures of complexes with antibodies, T-cell receptors or MHC molecules are available in the Protein Data Bank (PDB). Journal articles that are primary citations of PDB structures and that define immune epitopes are curated within IEDB as any other reference along with accompanying functional assays and immunologically relevant information. For each curated structure, IEDB-3D provides calculated data on intermolecular contacts and interface areas and includes an application, EpitopeViewer, to visualize the structures. IEDB-3D is fully embedded within IEDB, thus allowing structural data, both curated and calculated, and all accompanying information to be queried using multiple search interfaces. These include queries for epitopes recognized in different pathogens, eliciting different functional immune responses, and recognized by different components of the immune system. The query results can be downloaded in Microsoft Excel format, or the entire database, together with structural data both curated and calculated, can be downloaded in either XML or MySQL formats.

BackgroundHuman papillomavirus (HPV) E6 and E7 oncoproteins play a crucial role in HPV-related diseases, such as cervical cancer, and can be used as ideal targets for therapeutic vaccines. Human leukocyte antigen (HLA) participates in the immune response to block HPV infection and invasion by its target/recognition function. HPV-33 and HPV-58 are highly prevalent among Chinese women. Therefore, it is of great significance to study the E6 and E7 region-specific gene polymorphisms of HPV-33 and HPV-58 in Southwest China and to identify ideal epitopes for vaccine design. Both HPV-33 and HPV-58 belong to α-9 genus HPV and are highly homologous, so their correlations are included in our research.MethodsTo study the E6 and E7 variations and polymorphisms of HPV-33 and HPV-58 in Southwest China, we collected samples, extracted and sequenced DNA, and identified variants. Nucleotide sequences were translated into amino acids by Mega 6.0 software. The physical/chemical properties, amino acid-conserved sequences and secondary structure of protein sequences were analysed by the Protparam server, ConSurf server and PSIPRED software. The T and B cell epitopes of the E6/E7 reference and variant sequences in HPV-33 and HPV-58 were predicted by the Immune Epitope Database (IEDB) analysis server and the ABCpred server, respectively.ResultsFive and seven optimal HLA-I restricted T cell epitopes were selected from HPV-33 and HPV-58 E6, respectively, and these optimal epitopes are mainly located in 41-58EVYDFAFADLTVVYREGN of HPV-33 E6 and 40-60SEVYDFVFADLRIVYRDGNPF of HPV-58 E6. Six optimal HLA-I-restricted T cell epitopes were selected from HPV-33 and HPV-58 E7, and these epitopes are mainly located in 77-90RTIQQLLMGTVNIV of HPV-33 E7 and 78-91RTLQQLLMGTCTIV of HPV-58 E7.ConclusionsHPV-33/HPV-58 E6/E7 gene polymorphisms and T/B cell epitopes of their reference and variant sequences were studied, and candidate epitopes were selected by bioinformatics techniques for therapeutic vaccine design for people in Southwest China. This study was the first to investigate the correlation of epitopes between HPV-33 and HPV-58. After experimental validation, these selected epitopes will be employed to induce a wide range of immune responses in heterogeneous HLA populations.

Over the past 20 years, the Immune Epitope Database (IEDB, iedb.org) has established itself as the foremost resource for immune epitope data. The IEDB catalogs published epitopes and their contextual experimental data in a freely searchable public resource. The IEDB team manually curates data from the literature into a structured format and spans infectious, allergic, autoimmune, and transplant diseases. Here, we describe the enhancements made since our 2018 paper, capturing user-directed updates to the search interface, advanced data exports, increases in data quality, and improved interoperability across related resources. As we look forward to the next 20 years, we are confident in our ability to meet the needs of our users and to contribute to the broader field of data standardization.

A Roadmap for the Immunomics of Category A–C Pathogens

The Immune Epitope Database (IEDB) project incorporates independently developed ontologies and controlled vocabularies into its curation and search interface. This simplifies curation practices, improves the user query experience and facilitates interoperability between the IEDB and other resources. While the use of independently developed ontologies has long been recommended as a best practice, there continues to be a significant number of projects that develop their own vocabularies instead, or that do not fully utilize the power of ontologies that they are using. We describe how we use ontologies in the IEDB, providing a concrete example of the benefits of ontologies in practice.Database URL:www.iedb.org

BackgroundMalaria is a life-threatening disease caused by protozoan parasite of genus Plasmodium. Various antigenic proteins of Plasmodium are considered as the major targets for the development of an effective vaccine. The aim of the current study was a comprehensive analysis of the experimentally validated epitopes of Plasmodium obtained from various immunoassays.MethodsPlasmodium species epitopes were prefetched from Immune Epitope Database (IEDB). Species specific classification of available epitopes was done for both human and murine malaria parasites. Further, these T cell and B cell epitopes along with MHC I/II binders of different Plasmodium species were examined to find out their capability to induce IFN-γ and IL-10 using IFNepitope and IL-10 Pred, respectively.ResultsThe species-specific classification of 6874 unique epitopes resulted in the selection of predominant human and murine Plasmodium species. Further, the attempt was made to analyse the immune reactivity of these epitopes for their ability to induce cytokines namely IFN-γ and IL-10. Total, 2775 epitopes were predicted to possess IFN-γ inducing ability, whereas 1275 epitopes were found to be involved in the induction of IL-10.ConclusionsThis study facilitates the assessment of Plasmodium epitopes and associated proteins as a potential approach to design and develop an epitope-based vaccine. Moreover, the results highlight the epitope-based immunization in malaria to induce a protective immune response.

Bioinformatics prediction of B and T cell epitopes within the spike and nucleocapsid proteins of SARS-CoV2

BackgroundStructural information about epitopes, particularly the three-dimensional (3D) structures of antigens in complex with immune receptors, presents a valuable source of data for immunology. This information is available in the Protein Data Bank (PDB) and provided in curated form by the Immune Epitope Database and Analysis Resource (IEDB). With continued growth in these data and the importance in understanding molecular level interactions of immunological interest there is a need for new specialized molecular visualization and analysis tools.ResultsThe EpitopeViewer is a platform-independent Java application for the visualization of the three-dimensional structure and sequence of epitopes and analyses of their interactions with antigen-specific receptors of the immune system (antibodies, T cell receptors and MHC molecules). The viewer renders both 3D views and two-dimensional plots of intermolecular interactions between the antigen and receptor(s) by reading curated data from the IEDB and/or calculated on-the-fly from atom coordinates from the PDB. The 3D views and associated interactions can be saved for future use and publication. The EpitopeViewer can be accessed from the IEDB Web site through the quick link 'Browse Records by 3D Structure.'ConclusionThe EpitopeViewer is designed and been tested for use by immunologists with little or no training in molecular graphics. The EpitopeViewer can be launched from most popular Web browsers without user intervention. A Java Runtime Environment (RJE) 1.4.2 or higher is required.

While unstructured data, such as free text, constitutes a large amount of publicly available biomedical data, it is underutilized in automated analyses due to the difficulty of extracting meaning from it. Normalizing free-text data, i.e., removing inessential variance, enables the use of structured vocabularies like ontologies to represent the data and allow for harmonized queries over it. This paper presents an adaptable tool for free-text normalization and an evaluation of the application of this tool to two different sets of unstructured biomedical data curated from the literature in the Immune Epitope Database (IEDB): age and data-location. Free text entries for the database fields for subject age (4095 distinct values) and publication data-location (251,810 distinct values) in the IEDB were analyzed. Normalization was performed in three steps, namely character normalization, word normalization, and phrase normalization, using generalizable rules developed and applied with the tool presented in this manuscript. For the age dataset, in the character stage, the application of 21 rules resulted in 99.97% output validity; in the word stage, the application of 94 rules resulted in 98.06% output validity; and in the phrase stage, the application of 16 rules resulted in 83.81% output validity. For the data-location dataset, in the character stage, the application of 39 rules resulted in 99.99% output validity; in the word stage, the application of 187 rules resulted in 98.46% output validity; and in the phrase stage, the application of 12 rules resulted in 97.95% output validity. We developed a generalizable approach for normalization of free text as found in database fields with content on a specific topic. Creating and testing the rules took a one-time effort for a given field that can now be applied to data as it is being curated. The standardization achieved in two datasets tested produces significantly reduced variance in the content which enhances the findability and usability of that data, chiefly by improving search functionality and enabling linkages with formal ontologies.

The Immune Epitope Database (IEDB, iedb.org) captures experimental data confined in figures, text and tables of the scientific literature, making it freely available and easily searchable to the public. The scope of the IEDB extends across immune epitope data related to all species studied and includes antibody, T cell, and MHC binding contexts associated with infectious, allergic, autoimmune, and transplant related diseases. Having been publicly accessible for >10 years, the recent focus of the IEDB has been improved query and reporting functionality to meet the needs of our users to access and summarize data that continues to grow in quantity and complexity. Here we present an update on our current efforts and future goals.