From IMGT-ONTOLOGY CLASSIFICATION Axiom to IMGT standardized gene and allele nomenclature: for immunoglobulins (IG) and T cell receptors (TR)

Antibody Sequence and Structure Analyses Using IMGT®: 30 Years of Immunoinformatics

IMGT^®, the international ImMunoGeneTics information system^®, http://www.imgt.org , the global reference in immunogenetics and immunoinformatics, was created in 1989 by Marie-Paule Lefranc (Université de Montpellier and CNRS) to manage the huge diversity of the antigen receptors, immunoglobulins (IG) or antibodies, and T cell receptors (TR) of the adaptive immune responses. The founding of IMGT^® marked the advent of immunoinformatics, which emerged at the interface between immunogenetics and bioinformatics. IMGT^® standardized analysis of the IG, TR, and major histocompatibility (MH) genes and proteins bridges the gap between sequences and three-dimensional (3D) structures, for all jawed vertebrates from fish to humans. This is achieved through the IMGT Scientific chart rules, based on the IMGT-ONTOLOGY axioms, and primarily CLASSIFICATION (IMGT gene and allele nomenclature) and NUMEROTATION (IMGT unique numbering and IMGT Colliers de Perles). IMGT^® comprises seven databases (IMGT/LIGM-DB for nucleotide sequences, IMGT/GENE-DB for genes and alleles, etc.), 17 tools (IMGT/V-QUEST, IMGT/JunctionAnalysis, IMGT/HighV-QUEST for NGS, etc.), and more than 20,000 Web resources. In this chapter, the focus is on the tools for amino acid sequences per domain (IMGT/DomainGapAlign and IMGT/Collier-de-Perles), and on the databases for receptors (IMGT/2Dstructure-DB and IMGT/3D-structure-DB) described per receptor, chain, and domain and, for 3D, with contact analysis, paratope, and epitope. The IMGT/mAb-DB is the query interface for monoclonal antibodies (mAb), fusion proteins for immune applications (FPIA), composite proteins for clinical applications (CPCA), and related proteins of interest (RPI) with links to IMGT^® 2D and 3D databases and to the World Health Organization (WHO) International Nonproprietary Names (INN) program lists. The chapter includes the human IG allotypes and antibody engineered variants for effector properties used in the description of therapeutical mAb.

IMGT/3Dstructure-DB: T-Cell Receptor TR Paratope and Peptide/Major Histocompatibility pMH Contact Sites and Epitope

T-cell receptors (TR), the antigen receptors of T cells, specifically recognize peptides presented by the major histocompatibility (MH) proteins, as peptide/MH (pMH), on the cell surface. The structure characterization of the trimolecular TR/pMH complexes is crucial to the fields of immunology, vaccination, and immunotherapy. IMGT/3Dstructure-DB is the three-dimensional (3-D) structure database of IMGT^®, the international ImMunoGenetics information system^®. By its creation, IMGT^® marks the advent of immunoinformatics, which emerged at the interface between immunogenetics and bioinformatics. The IMGT^® immunoglobulin (IG) and TR gene and allele nomenclature (CLASSIFICATION axiom) and the IMGT unique numbering and IMGT/Collier-de-Perles (NUMEROTATION axiom) are the two founding breakthroughs of immunoinformatics. IMGT-ONTOLOGY concepts and IMGT Scientific chart rules generated from these axioms allowed IMGT^® bridging genes, structures, and functions. IMGT/3Dstructure-DB contains 3-D structures of IG or antibodies, TR and MH proteins of the adaptive immune responses of jawed vertebrates (gnathostomata), IG or TR complexes with antigens (IG/Ag, TR/pMH), related proteins of the immune system of any species belonging to the IG and MH superfamilies, and fusion proteins for immune applications. The focus of this chapter is on the TR V domains and MH G domains and the contact analysis comparison in TR/pMH interactions. Standardized molecular characterization includes "IMGT pMH contact sites" for peptide and MH groove interactions and "IMGT paratopes and epitopes" for TR/pMH complexes. Data are available in the IMGT/3Dstructure database, at the IMGT Home page http://www.imgt.org .

IMGT®Homo sapiens IG and TR Loci, Gene Order, CNV and Haplotypes: New Concepts as a Paradigm for Jawed Vertebrates Genome Assemblies

IMGT®, the international ImMunoGeneTics information system®, created in 1989, by Marie-Paule Lefranc (Université de Montpellier and CNRS), marked the advent of immunoinformatics, a new science which emerged at the interface between immunogenetics and bioinformatics for the study of the adaptive immune responses. IMGT® is based on a standardized nomenclature of the immunoglobulin (IG) and T cell receptor (TR) genes and alleles from fish to humans and on the IMGT unique numbering for the variable (V) and constant (C) domains of the immunoglobulin superfamily (IgSF) of vertebrates and invertebrates, and for the groove (G) domain of the major histocompatibility (MH) and MH superfamily (MhSF) proteins. IMGT® comprises 7 databases, 17 tools and more than 25,000 pages of web resources for sequences, genes and structures, based on the IMGT Scientific chart rules generated from the IMGT-ONTOLOGY axioms and concepts. IMGT® reference directories are used for the analysis of the NGS high-throughput expressed IG and TR repertoires (natural, synthetic and/or bioengineered) and for bridging sequences, two-dimensional (2D) and three-dimensional (3D) structures. This manuscript focuses on the IMGT®Homo sapiens IG and TR loci, gene order, copy number variation (CNV) and haplotypes new concepts, as a paradigm for jawed vertebrates genome assemblies.

IMGT® Immunoinformatics Tools for Standardized V-DOMAIN Analysis

The variable domains (V-DOMAIN) of the antigen receptors, immunoglobulins (IG) or antibodies and T cell receptors (TR), which specifically recognize the antigens show a huge diversity in their sequences. This diversity results from the complex mechanisms involved in the synthesis of these domains at the DNA level (rearrangements of the variable (V), diversity (D), and joining (J) genes; N-diversity; and, for the IG, somatic hypermutations). The recognition of V, D, and J as "genes" and their entry in databases mark the creation of IMGT by Marie-Paule Lefranc, and the origin of immunoinformatics in 1989. For 30 years, IMGT^®, the international ImMunoGeneTics information system^® http://www.imgt.org , has implemented databases and developed tools for IG and TR immunoinformatics, based on the IMGT Scientific chart rules and IMGT-ONTOLOGY concepts and axioms, and more particularly, the princeps ones: IMGT genes and alleles (CLASSIFICATION axiom) and the IMGT unique numbering and IMGT Collier de Perles (NUMEROTATION axiom). This chapter describes the online tools for the characterization and annotation of the expressed V-DOMAIN sequences: (a) IMGT/V-QUEST analyzes in detail IG and TR rearranged nucleotide sequences, (b) IMGT/HighV-QUEST is its high throughput version, which includes a module for the identification of IMGT clonotypes and generates immunoprofiles of expressed V, D, and J genes and alleles, (c) IMGT/StatClonotype performs the pairwise comparison of IMGT/HighV-QUEST immunoprofiles, (d) IMGT/DomainGapAlign analyzes amino acid sequences and is frequently used in antibody engineering and humanization, and (e) IMGT/Collier-de-Perles provides two-dimensional (2D) graphical representations of V-DOMAIN, bridging the gap between sequences and 3D structures. These IMGT® tools are widely used in repertoire analyses of the adaptive immune responses in normal and pathological situations and in the design of engineered IG and TR for therapeutic applications.

The Genomic Organisation of the TRA/TRD Locus Validates the Peculiar Characteristics of Dromedary δ-Chain Expression

The role of γδ T cells in vertebrate immunity is still an unsolved puzzle. Species such as humans and mice display a low percentage of these T lymphocytes (i.e., “γδ low species”) with a restricted diversity of γδ T cell receptors (TR). Conversely, artiodactyl species (i.e., “γδ high species”) account for a high proportion of γδ T cells with large γ and δ chain repertoires. The genomic organisation of the TR γ (TRG) and δ (TRD) loci has been determined in sheep and cattle, noting that a wide number of germline genes that encode for γ and δ chains characterise their genomes. Taking advantage of the current improved version of the genome assembly, we have investigated the genomic structure and gene content of the dromedary TRD locus, which, as in the other mammalian species, is nested within the TR α (TRA) genes. The most remarkable finding was the identification of a very limited number of variable germline genes (TRDV) compared to sheep and cattle, which supports our previous expression analyses for which the somatic hypermutation mechanism is able to enlarge and diversify the primary repertoire of dromedary δ chains. Furthermore, the comparison between genomic and expressed sequences reveals that D genes, up to four incorporated in a transcript, greatly contribute to the increased diversity of the dromedary δ chain antigen binding-site.

Immunoglobulins or Antibodies: IMGT® Bridging Genes, Structures and Functions

IMGT®, the international ImMunoGeneTics® information system founded in 1989 by Marie-Paule Lefranc (Université de Montpellier and CNRS), marked the advent of immunoinformatics, a new science at the interface between immunogenetics and bioinformatics. For the first time, the immunoglobulin (IG) or antibody and T cell receptor (TR) genes were officially recognized as 'genes' as well as were conventional genes. This major breakthrough has allowed the entry, in genomic databases, of the IG and TR variable (V), diversity (D) and joining (J) genes and alleles of Homo sapiens and of other jawed vertebrate species, based on the CLASSIFICATION axiom. The second major breakthrough has been the IMGT unique numbering and the IMGT Collier de Perles for the V and constant (C) domains of the IG and TR and other proteins of the IG superfamily (IgSF), based on the NUMEROTATION axiom. IMGT-ONTOLOGY axioms and concepts bridge genes, sequences, structures and functions, between biological and computational spheres in the IMGT® system (Web resources, databases and tools). They provide the IMGT Scientific chart rules to identify, to describe and to analyse the IG complex molecular data, the huge diversity of repertoires, the genetic (alleles, allotypes, CNV) polymorphisms, the IG dual function (paratope/epitope, effector properties), the antibody humanization and engineering.

Inferred Allelic Variants of Immunoglobulin Receptor Genes: A System for Their Evaluation, Documentation, and Naming

Immunoglobulins or antibodies are the main effector molecules of the B-cell lineage and are encoded by hundreds of variable (V), diversity (D), and joining (J) germline genes, which recombine to generate enormous IG diversity. Recently, high-throughput adaptive immune receptor repertoire sequencing (AIRR-seq) of recombined V-(D)-J genes has offered unprecedented insights into the dynamics of IG repertoires in health and disease. Faithful biological interpretation of AIRR-seq studies depends upon the annotation of raw AIRR-seq data, using reference germline gene databases to identify the germline genes within each rearrangement. Existing reference databases are incomplete, as shown by recent AIRR-seq studies that have inferred the existence of many previously unreported polymorphisms. Completing the documentation of genetic variation in germline gene databases is therefore of crucial importance. Lymphocyte receptor genes and alleles are currently assigned by the Immunoglobulins, T cell Receptors and Major Histocompatibility Nomenclature Subcommittee of the International Union of Immunological Societies (IUIS) and managed in IMGT®, the international ImMunoGeneTics information system® (IMGT). In 2017, the IMGT Group reached agreement with a group of AIRR-seq researchers on the principles of a streamlined process for identifying and naming inferred allelic sequences, for their incorporation into IMGT®. These researchers represented the AIRR Community, a network of over 300 researchers whose objective is to promote all aspects of immunoglobulin and T-cell receptor repertoire studies, including the standardization of experimental and computational aspects of AIRR-seq data generation and analysis. The Inferred Allele Review Committee (IARC) was established by the AIRR Community to devise policies, criteria, and procedures to perform this function. Formalized evaluations of novel inferred sequences have now begun and submissions are invited via a new dedicated portal (https://ogrdb.airr-community.org). Here, we summarize recommendations developed by the IARC-focusing, to begin with, on human IGHV genes-with the goal of facilitating the acceptance of inferred allelic variants of germline IGHV genes. We believe that this initiative will improve the quality of AIRR-seq studies by facilitating the description of human IG germline gene variation, and that in time, it will expand to the documentation of TR and IG genes in many vertebrate species.

Use of IMGT® Databases and Tools for Antibody Engineering and Humanization

IMGT^®, the international ImMunoGeneTics information system^® ( http://www.imgt.org ), was created in 1989 by Marie-Paule Lefranc (Université de Montpellier and CNRS) to manage the huge diversity of the antigen receptors, immunoglobulins (IG) or antibodies, and T cell receptors (TR). The founding of IMGT^® marked the advent of immunoinformatics, which emerged at the interface between immunogenetics and bioinformatics. Standardized sequence and structure analysis of antibody using IMGT^® databases and tools allow one to bridge, for the first time, the gap between antibody sequences and three-dimensional (3D) structures. This is achieved through the IMGT Scientific chart rules, based on the IMGT-ONTOLOGY concepts of classification (IMGT gene and allele nomenclature), description (IMGT standardized labels), and numerotation (IMGT unique numbering and IMGT Collier de Perles). IMGT^® is acknowledged as the global reference for immunogenetics and immunoinformatics, and its standards are particularly useful for antibody engineering and humanization. IMGT^® databases for antibody nucleotide sequences and genes include IMGT/LIGM-DB and IMGT/GENE-DB, respectively, and nucleotide sequence analysis is performed by the IMGT/V-QUEST and IMGT/JunctionAnalysis tools and for NGS by IMGT/HighV-QUEST. In this chapter, we focus on IMGT^® databases and tools for amino acid sequences, two-dimensional (2D) and three-dimensional (3D) structures: the IMGT/DomainGapAlign and IMGT Collier de Perles tools and the IMGT/2Dstructure-DB and IMGT/3Dstructure-DB database. IMGT/mAb-DB provides the query interface for monoclonal antibodies (mAb), fusion proteins for immune applications (FPIA), and composite proteins for clinical applications (CPCA) and related proteins of interest (RPI) and links to the proposed and recommended lists of the World Health Organization International Nonproprietary Name (WHO INN) programme, to IMGT/2Dstructure-DB for amino acid sequences, and to IMGT/3Dstructure-DB and its associated tools (IMGT/StructuralQuery, IMGT/DomainSuperimpose) for crystallized antibodies.

Data on haplotype-supported immunoglobulin germline gene inference

Data that defines IGHV (immunoglobulin heavy chain variable) germline gene inference using sequences of IgM-encoding transcriptomes obtained by Illumina MiSeq sequencing technology are described. Such inference is used to establish personalized germline gene sets for in-depth antibody repertoire studies and to detect new antibody germline genes from widely available immunoglobulin-encoding transcriptome data sets. Specifically, the data has been used to validate (Parallel antibody germline gene and haplotype analyses support the validity of immunoglobulin germline gene inference and discovery (DOI: 10.1016/j.molimm.2017.03.012) (Kirik et al., 2017) [1]) the inference process. This was accomplished based on analysis of the inferred germline genes’ association to the donors’ different haplotypes as defined by their different, expressed IGHJ alleles and/or IGHD genes/alleles. The data is important for development of validated germline gene databases containing entries inferred from immunoglobulin-encoding transcriptome sequencing data sets, and for generation of valid, personalized antibody germline gene repertoires.

IG and TR single chain fragment variable (scFv) sequence analysis: a new advanced functionality of IMGT/V-QUEST and IMGT/HighV-QUEST

BACKGROUND

IMGT®, the international ImMunoGeneTics information system® ( http://www.imgt.org ), was created in 1989 in Montpellier, France (CNRS and Montpellier University) to manage the huge and complex diversity of the antigen receptors, and is at the origin of immunoinformatics, a science at the interface between immunogenetics and bioinformatics. Immunoglobulins (IG) or antibodies and T cell receptors (TR) are managed and described in the IMGT® databases and tools at the level of receptor, chain and domain. The analysis of the IG and TR variable (V) domain rearranged nucleotide sequences is performed by IMGT/V-QUEST (online since 1997, 50 sequences per batch) and, for next generation sequencing (NGS), by IMGT/HighV-QUEST, the high throughput version of IMGT/V-QUEST (portal begun in 2010, 500,000 sequences per batch). In vitro combinatorial libraries of engineered antibody single chain Fragment variable (scFv) which mimic the in vivo natural diversity of the immune adaptive responses are extensively screened for the discovery of novel antigen binding specificities. However the analysis of NGS full length scFv (~850 bp) represents a challenge as they contain two V domains connected by a linker and there is no tool for the analysis of two V domains in a single chain.

METHODS

The functionality "Analyis of single chain Fragment variable (scFv)" has been implemented in IMGT/V-QUEST and, for NGS, in IMGT/HighV-QUEST for the analysis of the two V domains of IG and TR scFv. It proceeds in five steps: search for a first closest V-REGION, full characterization of the first V-(D)-J-REGION, then search for a second V-REGION and full characterization of the second V-(D)-J-REGION, and finally linker delimitation.

RESULTS

For each sequence or NGS read, positions of the 5'V-DOMAIN, linker and 3'V-DOMAIN in the scFv are provided in the 'V-orientated' sense. Each V-DOMAIN is fully characterized (gene identification, sequence description, junction analysis, characterization of mutations and amino changes). The functionality is generic and can analyse any IG or TR single chain nucleotide sequence containing two V domains, provided that the corresponding species IMGT reference directory is available.

CONCLUSION

The "Analysis of single chain Fragment variable (scFv)" implemented in IMGT/V-QUEST and, for NGS, in IMGT/HighV-QUEST provides the identification and full characterization of the two V domains of full-length scFv (~850 bp) nucleotide sequences from combinatorial libraries. The analysis can also be performed on concatenated paired chains of expressed antigen receptor IG or TR repertoires.

Immunoglobulins: 25 years of immunoinformatics and IMGT-ONTOLOGY

IMGT®, the international ImMunoGeneTics information system® (CNRS and Montpellier University) is the global reference in immunogenetics and immunoinformatics. By its creation in 1989, IMGT® marked the advent of immunoinformatics, which emerged at the interface between immunogenetics and bioinformatics. IMGT® is specialized in the immunoglobulins (IG) or antibodies, T cell receptors (TR), major histocompatibility (MH), and IgSF and MhSF superfamilies. IMGT® has been built on the IMGT-ONTOLOGY axioms and concepts, which bridged the gap between genes, sequences and three-dimensional (3D) structures. The concepts include the IMGT® standardized keywords (identification), IMGT® standardized labels (description), IMGT® standardized nomenclature (classification), IMGT unique numbering and IMGT Colliers de Perles (numerotation). IMGT® comprises seven databases, 15,000 pages of web resources and 17 tools. IMGT® tools and databases provide a high-quality analysis of the IG from fish to humans, for basic, veterinary and medical research, and for antibody engineering and humanization. They include, as examples: IMGT/V-QUEST and IMGT/JunctionAnalysis for nucleotide sequence analysis and their high-throughput version IMGT/HighV-QUEST for next generation sequencing, IMGT/DomainGapAlign for amino acid sequence analysis of IG domains, IMGT/3Dstructure-DB for 3D structures, contact analysis and paratope/epitope interactions of IG/antigen complexes, and the IMGT/mAb-DB interface for therapeutic antibodies and fusion proteins for immunological applications (FPIA).

IMGT®, the international ImMunoGeneTics information system® 25 years on

IMGT^®, the international ImMunoGeneTics information system^®(http://www.imgt.org) is the global reference in immunogenetics and immunoinformatics. By its creation in 1989 by Marie-Paule Lefranc (Université de Montpellier and CNRS), IMGT^® marked the advent of immunoinformatics, which emerged at the interface between immunogenetics and bioinformatics. IMGT^® is specialized in the immunoglobulins (IG) or antibodies, T cell receptors (TR), major histocompatibility (MH) and proteins of the IgSF and MhSF superfamilies. IMGT^® is built on the IMGT-ONTOLOGY axioms and concepts, which bridged the gap between genes, sequences and 3D structures. The concepts include the IMGT^® standardized keywords (identification), IMGT^® standardized labels (description), IMGT^® standardized nomenclature (classification), IMGT unique numbering and IMGT Colliers de Perles (numerotation). IMGT^® comprises 7 databases, 17 online tools and 15 000 pages of web resources, and provides a high-quality and integrated system for analysis of the genomic and expressed IG and TR repertoire of the adaptive immune responses, including NGS high-throughput data. Tools and databases are used in basic, veterinary and medical research, in clinical applications (mutation analysis in leukemia and lymphoma) and in antibody engineering and humanization. The IMGT/mAb-DB interface was developed for therapeutic antibodies and fusion proteins for immunological applications (FPIA). IMGT^® is freely available at http://www.imgt.org.

Antibody V and C domain sequence, structure, and interaction analysis with special reference to IMGT®

IMGT(®), the international ImMunoGeneTics information system(®) (http://www.imgt.org), created in 1989 (Centre National de la Recherche Scientifique, Montpellier University), is acknowledged as the global reference in immunogenetics and immunoinformatics. The accuracy and the consistency of the IMGT(®) data are based on IMGT-ONTOLOGY which bridges the gap between genes, sequences, and three-dimensional (3D) structures. Thus, receptors, chains, and domains are characterized with the same IMGT(®) rules and standards (IMGT standardized labels, IMGT gene and allele nomenclature, IMGT unique numbering, IMGT Collier de Perles), independently from the molecule type (genomic DNA, complementary DNA, transcript, or protein) or from the species. More particularly, IMGT(®) tools and databases provide a highly standardized analysis of the immunoglobulin (IG) or antibody and T cell receptor (TR) V and C domains. IMGT/V-QUEST analyzes the V domains of IG or TR rearranged nucleotide sequences, integrates the IMGT/JunctionAnalysis and IMGT/Automat tools, and provides IMGT Collier de Perles. IMGT/HighV-QUEST analyzes sequences from high-throughput sequencing (HTS) (up to 150,000 sequences per batch) and performs statistical analysis on up to 450,000 results, with the same resolution and high quality as IMGT/V-QUEST online. IMGT/DomainGapAlign analyzes amino acid sequences of V and C domains and IMGT/3Dstructure-DB and associated tools provide information on 3D structures, contact analysis, and paratope/epitope interactions. These IMGT(®) tools and databases, and the IMGT/mAb-DB interface with access to therapeutical antibody data, provide an invaluable help for antibody engineering and antibody humanization.

Comparative analysis of human and mouse immunoglobulin variable heavy regions from IMGT/LIGM-DB with IMGT/HighV-QUEST

Background

Immunoglobulin (IG) complementarity determining region (CDR) includes VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2 and VL CDR3. Of these, VH CDR3 plays a dominant role in recognizing and binding antigens. Three major mechanisms are involved in the formation of the VH repertoire: germline gene rearrangement, junctional diversity and somatic hypermutation. Features of the generation mechanisms of VH repertoire in humans and mice share similarities while VH CDR3 amino acid (AA) composition differs. Previous studies have mainly focused on germline gene rearrangement and the composition and structure of the CDR3 AA in humans and mice. However the number of AA changes due to somatic hypermutation and analysis of the junctional mechanism have been ignored.

Methods

Here we analyzed 9,340 human and 6,657 murine unique productive sequences of immunoglobulin (IG) variable heavy (VH) domains derived from IMGT/LIGM-DB database to understand how VH CDR3 AA compositions significantly differed between human and mouse. These sequences were identified and analyzed by IMGT/HighV-QUEST (http://www.imgt.org), including gene usage, number of AA changes due to somatic hypermutation, AA length distribution of VH CDR3, AA composition, and junctional diversity.

Results

Analyses of human and murine IG repertoires showed significant differences. A higher number of AA changes due to somatic hypermutation and more abundant N-region addition were found in human compared to mouse, which might be an important factor leading to differences in VH CDR3 amino acid composition.

Conclusions

These findings are a benchmark for understanding VH repertoires and can be used to characterize the VH repertoire during immune responses. The study will allow standardized comparison for high throughput results obtained by IMGT/HighV-QUEST, the reference portal for NGS repertoire.

Characterization of human αβTCR repertoire and discovery of D-D fusion in TCRβ chains

The characterization of the human T-cell receptor (TCR) repertoire has made remarkable progress, with most of the work focusing on the TCRβ chains. Here, we analyzed the diversity and complexity of both the TCRα and TCRβ repertoires of three healthy donors. We found that the diversity of the TCRα repertoire is higher than that of the TCRβ repertoire, whereas the usages of the V and J genes tended to be preferential with similar TRAV and TRAJ patterns in all three donors. The V-J pairings, like the V and J gene usages, were slightly preferential. We also found that the TRDV1 gene rearranges with the majority of TRAJ genes, suggesting that TRDV1 is a shared TRAV/DV gene (TRAV42/DV1). Moreover, we uncovered the presence of tandem TRBD (TRB D gene) usage in ~2% of the productive human TCRβ CDR3 sequences.

IMGT/HighV QUEST paradigm for T cell receptor IMGT clonotype diversity and next generation repertoire immunoprofiling

T cell repertoire diversity and clonotype follow-up in vaccination, cancer, infectious and immune diseases represent a major challenge owing to the enormous complexity of the data generated. Here we describe a next generation methodology, which combines 5'RACE PCR, 454 sequencing and, for analysis, IMGT, the international ImMunoGeneTics information system (IMGT), IMGT/HighV-QUEST web portal and IMGT-ONTOLOGY concepts. The approach is validated in a human case study of T cell receptor beta (TRB) repertoire, by chronologically tracking the effects of influenza vaccination on conventional and regulatory T cell subpopulations. The IMGT/HighV-QUEST paradigm defines standards for genotype/haplotype analysis and characterization of IMGT clonotypes for clonal diversity and expression and achieves a degree of resolution for next generation sequencing verifiable by the user at the sequence level, while providing a normalized reference immunoprofile for human TRB.

Antibody Informatics: IMGT, the International ImMunoGeneTics Information System

Antibody informatics, a part of immunoinformatics, refers to the concepts, databases, and tools developed and used to explore and to analyze the particular properties of the immunoglobulins (IG) or antibodies, compared with conventional genes and proteins. Antibody informatics is based on a unique ontology, IMGT-ONTOLOGY, created in 1989 by IMGT, the international ImMunoGeneTics information system ( http://www.imgt.org ). IMGT-ONTOLOGY defined, for the first time, the concept of ‘genes’ for the IG and the T cell receptors (TR), which led to their gene and allele nomenclature and allowed their entry in databases and tools. A second IMGT-ONTOLOGY revolutionizing and definitive concept was the IMGT unique numbering that bridged the gap between sequences and structures for the variable (V) and constant (C) domains of the IG and TR, and for the groove (G) domains of the major histocompatibility (MH). These breakthroughs contributed to the development of IMGT databases and tools for antibody informatics and its diverse applications, such as repertoire analysis in infectious diseases, antibody engineering and humanization, and study of antibody/antigen interactions. Nucleotide sequences of antibody V domains from deep sequencing (Next Generation Sequencing or High Throughput Sequencing) are analyzed with IMGT/HighV-QUEST, the high-throughput version of IMGT/V-QUEST and IMGT/JunctionAnalysis. Amino acid sequences of V and C domains are represented with the IMGT/Collier-de-Perles tool and analyzed with IMGT/DomainGapAlign. Three-dimensional (3D) structures (including contact analysis and paratope/epitope) are described in IMGT/3Dstructure-DB. Based on a friendly interface, IMGT/mAb-DB contains therapeutic monoclonal antibodies (INN suffix–mab) that can be queried on their specificity, for example, in infectious diseases, on bacterial or viral targets.

Immunoglobulin and T Cell Receptor Genes: IMGT(®) and the Birth and Rise of Immunoinformatics

IMGT(®), the international ImMunoGeneTics information system(®) (1), (CNRS and Université Montpellier 2) is the global reference in immunogenetics and immunoinformatics. By its creation in 1989, IMGT(®) marked the advent of immunoinformatics, which emerged at the interface between immunogenetics and bioinformatics. IMGT(®) is specialized in the immunoglobulins (IG) or antibodies, T cell receptors (TR), major histocompatibility (MH), and proteins of the IgSF and MhSF superfamilies. IMGT(®) has been built on the IMGT-ONTOLOGY axioms and concepts, which bridged the gap between genes, sequences, and three-dimensional (3D) structures. The concepts include the IMGT(®) standardized keywords (concepts of identification), IMGT(®) standardized labels (concepts of description), IMGT(®) standardized nomenclature (concepts of classification), IMGT unique numbering, and IMGT Colliers de Perles (concepts of numerotation). IMGT(®) comprises seven databases, 15,000 pages of web resources, and 17 tools, and provides a high-quality and integrated system for the analysis of the genomic and expressed IG and TR repertoire of the adaptive immune responses. Tools and databases are used in basic, veterinary, and medical research, in clinical applications (mutation analysis in leukemia and lymphoma) and in antibody engineering and humanization. They include, for example IMGT/V-QUEST and IMGT/JunctionAnalysis for nucleotide sequence analysis and their high-throughput version IMGT/HighV-QUEST for next-generation sequencing (500,000 sequences per batch), IMGT/DomainGapAlign for amino acid sequence analysis of IG and TR variable and constant domains and of MH groove domains, IMGT/3Dstructure-DB for 3D structures, contact analysis and paratope/epitope interactions of IG/antigen and TR/peptide-MH complexes and IMGT/mAb-DB interface for therapeutic antibodies and fusion proteins for immune applications (FPIA).

The past, present, and future of immune repertoire biology - the rise of next-generation repertoire analysis

T and B cell repertoires are collections of lymphocytes, each characterized by its antigen-specific receptor. We review here classical technologies and analysis strategies developed to assess immunoglobulin (IG) and T cell receptor (TR) repertoire diversity, and describe recent advances in the field. First, we describe the broad range of available methodological tools developed in the past decades, each of which answering different questions and showing complementarity for progressive identification of the level of repertoire alterations: global overview of the diversity by flow cytometry, IG repertoire descriptions at the protein level for the identification of IG reactivities, IG/TR CDR3 spectratyping strategies, and related molecular quantification or dynamics of T/B cell differentiation. Additionally, we introduce the recent technological advances in molecular biology tools allowing deeper analysis of IG/TR diversity by next-generation sequencing (NGS), offering systematic and comprehensive sequencing of IG/TR transcripts in a short amount of time. NGS provides several angles of analysis such as clonotype frequency, CDR3 diversity, CDR3 sequence analysis, V allele identification with a quantitative dimension, therefore requiring high-throughput analysis tools development. In this line, we discuss the recent efforts made for nomenclature standardization and ontology development. We then present the variety of available statistical analysis and modeling approaches developed with regards to the various levels of diversity analysis, and reveal the increasing sophistication of those modeling approaches. To conclude, we provide some examples of recent mathematical modeling strategies and perspectives that illustrate the active rise of a "next-generation" of repertoire analysis.

Complete haplotype sequence of the human immunoglobulin heavy-chain variable, diversity, and joining genes and characterization of allelic and copy-number variation

The immunoglobulin heavy-chain locus (IGH) encodes variable (IGHV), diversity (IGHD), joining (IGHJ), and constant (IGHC) genes and is responsible for antibody heavy-chain biosynthesis, which is vital to the adaptive immune response. Programmed V-(D)-J somatic rearrangement and the complex duplicated nature of the locus have impeded attempts to reconcile its genomic organization based on traditional B-lymphocyte derived genetic material. As a result, sequence descriptions of germline variation within IGHV are lacking, haplotype inference using traditional linkage disequilibrium methods has been difficult, and the human genome reference assembly is missing several expressed IGHV genes. By using a hydatidiform mole BAC clone resource, we present the most complete haplotype of IGHV, IGHD, and IGHJ gene regions derived from a single chromosome, representing an alternate assembly of ∼1 Mbp of high-quality finished sequence. From this we add 101 kbp of previously uncharacterized sequence, including functional IGHV genes, and characterize four large germline copy-number variants (CNVs). In addition to this germline reference, we identify and characterize eight CNV-containing haplotypes from a panel of nine diploid genomes of diverse ethnic origin, discovering previously unmapped IGHV genes and an additional 121 kbp of insertion sequence. We genotype four of these CNVs by using PCR in 425 individuals from nine human populations. We find that all four are highly polymorphic and show considerable evidence of stratification (Fst = 0.3-0.5), with the greatest differences observed between African and Asian populations. These CNVs exhibit weak linkage disequilibrium with SNPs from two commercial arrays in most of the populations tested.

Use of IMGT(®) databases and tools for antibody engineering and humanization

IMGT(®), the international ImMunoGeneTics information system(®) (http://www.imgt.org), was created in 1989 to manage the huge diversity of the antigen receptors, immunoglobulins (IG) or antibodies, and T cell receptors (TR). Standardized sequence and structure analysis of antibody using IMGT(®) databases and tools allows one to bridge, for the first time, the gap between antibody sequences and three-dimensional (3D) structures. This is achieved through the IMGT Scientific chart rules, based on the IMGT-ONTOLOGY concepts of classification (IMGT gene and allele nomenclature), description (IMGT standardized labels), and numerotation (IMGT unique numbering and IMGT Colliers de Perles). IMGT(®) is the international reference for immunogenetics and immunoinformatics and its standards are particularly useful for antibody humanization and evaluation of immunogenicity. IMGT(®) databases for antibody nucleotide sequences and genes include IMGT/LIGM-DB and IMGT/GENE-DB, respectively, whereas nucleotide sequence analysis is performed by the IMGT/V-QUEST, IMGT/HighV-QUEST, and IMGT/JunctionAnalysis tools. In this chapter, we focus on IMGT(®) databases and tools for amino acid sequences, two-dimensional (2D) and three-dimensional (3D) structures: the IMGT/DomainGapAlign and IMGT/Collier-de-Perles tools, the IMGT/2Dstructure-DB database for amino acid sequences of monoclonal antibodies (mAb, suffix -mab) and fusion proteins for immune applications (FPIA, suffix -cept) of the World Health Organization/International Nonproprietary Name (WHO/INN) programme and other proteins of interest, and the IMGT/3Dstructure-DB database for crystallized antibodies and its associated tools (IMGT/StructuralQuery, IMGT/DomainSuperimpose).

Gene family matters: expanding the HGNC resource

The HUGO Gene Nomenclature Committee (HGNC) assigns approved gene symbols to human loci. There are currently over 33,000 approved gene symbols, the majority of which represent protein-coding genes, but we also name other locus types such as non-coding RNAs, pseudogenes and phenotypic loci. Where relevant, the HGNC organise these genes into gene families and groups. The HGNC website http://www.genenames.org/ is an online repository of HGNC-approved gene nomenclature and associated resources for human genes, and includes links to genomic, proteomic and phenotypic information. In addition to this, we also have dedicated gene family web pages and are currently expanding and generating more of these pages using data curated by the HGNC and from information derived from external resources that focus on particular gene families. Here, we review our current online resources with a particular focus on our gene family data, using it to highlight our new Gene Symbol Report and gene family data downloads.

IMGT-ONTOLOGY 2012

Immunogenetics is the science that studies the genetics of the immune system and immune responses. Owing to the complexity and diversity of the immune repertoire, immunogenetics represents one of the greatest challenges for data interpretation: a large biological expertise, a considerable effort of standardization and the elaboration of an efficient system for the management of the related knowledge were required. IMGT^®, the international ImMunoGeneTics information system^® (http://www.imgt.org) has reached that goal through the building of a unique ontology, IMGT-ONTOLOGY, which represents the first ontology for the formal representation of knowledge in immunogenetics and immunoinformatics. IMGT-ONTOLOGY manages the immunogenetics knowledge through diverse facets that rely on the seven axioms of the Formal IMGT-ONTOLOGY or IMGT-Kaleidoscope: “IDENTIFICATION,” “DESCRIPTION,” “CLASSIFICATION,” “NUMEROTATION,” “LOCALIZATION,” “ORIENTATION,” and “OBTENTION.” The concepts of identification, description, classification, and numerotation generated from the axioms led to the elaboration of the IMGT^® standards that constitute the IMGT Scientific chart: IMGT^® standardized keywords (concepts of identification), IMGT^® standardized labels (concepts of description), IMGT^® standardized gene and allele nomenclature (concepts of classification) and IMGT unique numbering and IMGT Collier de Perles (concepts of numerotation). IMGT-ONTOLOGY has become the global reference in immunogenetics and immunoinformatics for the knowledge representation of immunoglobulins (IG) or antibodies, T cell receptors (TR), and major histocompatibility (MH) proteins of humans and other vertebrates, proteins of the immunoglobulin superfamily (IgSF) and MH superfamily (MhSF), related proteins of the immune system (RPI) of vertebrates and invertebrates, therapeutic monoclonal antibodies (mAbs), fusion proteins for immune applications (FPIA), and composite proteins for clinical applications (CPCA).

IMGT/junctionanalysis: IMGT standardized analysis of the V-J and V-D-J junctions of the rearranged immunoglobulins (IG) and T cell receptors (TR)

IMGT/JunctionAnalysis is the online IMGT tool for the detailed and standardized analysis of the junctions between the variable (V), diversity (D), and joining (J) genes (V-J and V-D-J junctions) of the rearranged immunoglobulin (IG) or antibody and T cell receptor (TR) variable domains. The V-(D)-J junctions comprise the rearranged CDR3-IMGT and its anchors 2nd-CYS 104 and J-PHE or J-TRP 118. The diversity of the junctions that determines the antigen receptor specificity results from complex molecular mechanisms that occur at the DNA level during the IG and TR synthesis and create combinatorial diversity, N-diversity and, for IG, somatic hypermutations. The annotation of V-J or V-D-J junctions in rearranged IG and TR sequences represents a huge challenge due to its uniqueness and complexity. IMGT/JunctionAnalysis has been a major breakthrough by providing, for the first time, a very detailed and accurate analysis of the junctions. The tool, whose use is described here, identifies the D genes in the IGH, TRB, and TRD junctions, the trimmed nucleotides (nt) at the end of the genes which recombine, and the palindromic P regions in the absence of gene trimming. It delimits the N regions that result from the N-diversity, calculates the ratio of G+C nucleotides in the N regions, and evaluates the number of somatic hypermutations for each gene within the junction.

IMGT Collier de Perles for the variable (V), constant (C), and groove (G) domains of IG, TR, MH, IgSF, and MhSF

The “IMGT Collier de Perles” (or “IMGT_Collier_de_Perles”) concept is a major concept of numerotation (generated from the NUMEROTATION axiom) of IMGT-ONTOLOGY, the global reference in immunogenetics and immunoinformatics, built by IMGT, the international ImMunoGeneTics information system. The “IMGT Collier de Perles” concept, described here, allows standardized two-dimensional (2D) graphical representations of the domains, based on the IMGT unique numbering. Three leafconcepts (a leafconcept is a concept that corresponds to the finest level of granularity) have been defined: for the variable (V) domain and constant (C) domain of the immunoglobulin superfamily (IgSF) and for the groove (G) domain of the major histocompatibility (MH) superfamily (MhSF). IMGT Colliers de Perles are obtained, starting from V, C, or G domain amino acid sequences, using IMGT/DomainGapAlign and IMGT/Collier de Perles tools. In IMGT/3Dstructure-DB, IMGT Colliers de Perles of V and C domains are provided with hydrogen bonds and those of G domains with IMGT pMH contact analysis. IMGT Colliers de Perles allows one to bridge the gap between sequences and three-dimensional (3D) structures, whatever the species, the IgSF or MhSF protein, or the chain type. They are particularly useful for antibody engineering, sequence-structure analysis, visualization and comparison of positions for mutations, polymorphisms and contact analysis of immunoglobulins (IG), T cell receptors (TR), MH, and related proteins of the immune system (RPI) belonging to the IgSF and MhSF.