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Frontiers in Immunology 2019The pneumoviruses respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are two widespread human pathogens that can cause severe disease in the young, the... (Review)
Review
The pneumoviruses respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are two widespread human pathogens that can cause severe disease in the young, the elderly, and the immunocompromised. Despite the discovery of RSV over 60 years ago, and hMPV nearly 20 years ago, there are no approved vaccines for either virus. Antibody-mediated immunity is critical for protection from RSV and hMPV, and, until recently, knowledge of the antibody epitopes on the surface glycoproteins of RSV and hMPV was very limited. However, recent breakthroughs in the recombinant expression and stabilization of pneumovirus fusion proteins have facilitated in-depth characterization of antibody responses and structural epitopes, and have provided an enormous diversity of new monoclonal antibody candidates for therapeutic development. These new data have primarily focused on the RSV F protein, and have led to a wealth of new vaccine candidates in preclinical and clinical trials. In contrast, the major structural antibody epitopes remain unclear for the hMPV F protein. Overall, this review will cover recent advances in characterizing the antigenic sites on the RSV and hMPV F proteins.
Topics: Antibodies, Monoclonal; Antibodies, Viral; Antigens, Viral; Cost of Illness; Epitopes; Global Health; Humans; Pneumovirus; Pneumovirus Infections; Protein Binding; Public Health Surveillance; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human; Structure-Activity Relationship; Viral Fusion Proteins
PubMed: 31849961
DOI: 10.3389/fimmu.2019.02778 -
International Journal of Molecular... Jan 2022Nanobodies, or VHHs, refer to the antigen-binding domain of heavy-chain antibodies (HCAbs) from camelids. They have been widely used as research tools for protein... (Review)
Review
Nanobodies, or VHHs, refer to the antigen-binding domain of heavy-chain antibodies (HCAbs) from camelids. They have been widely used as research tools for protein purification and structure determination due to their small size, high specificity, and high stability, overcoming limitations with conventional antibody fragments. However, animal immunization and subsequent retrieval of antigen-specific nanobodies are expensive and complicated. Construction of synthetic nanobody libraries using DNA oligonucleotides is a cost-effective alternative for immunization libraries and shows great potential in identifying antigen-specific or even conformation-specific nanobodies. This review summarizes and analyses synthetic nanobody libraries in the current literature, including library design and biopanning methods, and further discusses applications of antigen-specific nanobodies obtained from synthetic libraries to research.
Topics: Animals; Antigens; Camelus; Chromatography, Affinity; Immunoglobulin Heavy Chains; Peptide Library; Single-Domain Antibodies
PubMed: 35163405
DOI: 10.3390/ijms23031482 -
The Journal of Biological Chemistry Jul 2023Chimeric antigen receptor (CAR) T-cell therapy has had considerable success in the treatment of B-cell malignancies. Targeting the B-lineage marker CD19 has brought...
Chimeric antigen receptor (CAR) T-cell therapy has had considerable success in the treatment of B-cell malignancies. Targeting the B-lineage marker CD19 has brought great advances to the treatment of acute lymphoblastic leukemia and B-cell lymphomas. However, relapse remains an issue in many cases. Such relapse can result from downregulation or loss of CD19 from the malignant cell population or expression of alternate isoforms. Consequently, there remains a need to target alternative B-cell antigens and diversify the spectrum of epitopes targeted within the same antigen. CD22 has been identified as a substitute target in cases of CD19-negative relapse. One anti-CD22 antibody-clone m971-targets a membrane-proximal epitope of CD22 and has been widely validated and used in the clinic. Here, we have compared m971-CAR with a novel CAR derived from IS7, an antibody that targets a central epitope on CD22. The IS7-CAR has superior avidity and is active and specific against CD22-positive targets, including B-acute lymphoblastic leukemia patient-derived xenograft samples. Side-by-side comparisons indicated that while IS7-CAR killed less rapidly than m971-CAR in vitro, it remains efficient in controlling lymphoma xenograft models in vivo. Thus, IS7-CAR presents a potential alternative candidate for the treatment of refractory B-cell malignancies.
Topics: Humans; Antigens, CD19; Epitopes; Immunotherapy, Adoptive; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Receptors, Chimeric Antigen; Recurrence; Sialic Acid Binding Ig-like Lectin 2
PubMed: 37269947
DOI: 10.1016/j.jbc.2023.104883 -
Frontiers in Immunology 2022T cell receptors (TCRs) recognize peptide antigens bound to major histocompatibility complex (MHC) molecules (p/MHC) that are expressed on cell surfaces; while B... (Review)
Review
T cell receptors (TCRs) recognize peptide antigens bound to major histocompatibility complex (MHC) molecules (p/MHC) that are expressed on cell surfaces; while B cell-derived antibodies (Abs) recognize soluble or cell surface native antigens of various types (proteins, carbohydrates, etc.). Immune surveillance by T and B cells thus inspects almost all formats of antigens to mount adaptive immune responses against cancer cells, infectious organisms and other foreign insults, while maintaining tolerance to self-tissues. With contributions from environmental triggers, the development of autoimmune disease is thought to be due to the expression of MHC risk alleles by antigen-presenting cells (APCs) presenting self-antigen (autoantigen), breaking through self-tolerance and activating autoreactive T cells, which orchestrate downstream pathologic events. Investigating and treating autoimmune diseases have been challenging, both because of the intrinsic complexity of these diseases and the need for tools targeting T cell epitopes (autoantigen-MHC). Naturally occurring TCRs with relatively low (micromolar) affinities to p/MHC are suboptimal for autoantigen-MHC targeting, whereas the use of engineered TCRs and their derivatives (e.g., TCR multimers and TCR-engineered T cells) are limited by unpredictable cross-reactivity. As Abs generally have nanomolar affinity, recent advances in engineering TCR-like (TCRL) Abs promise advantages over their TCR counterparts for autoantigen-MHC targeting. Here, we compare the p/MHC binding by TCRs and TCRL Abs, review the strategies for generation of TCRL Abs, highlight their application for identification of autoantigen-presenting APCs, and discuss future directions and limitations of TCRL Abs as immunotherapy for autoimmune diseases.
Topics: Antibodies; Autoantigens; Autoimmune Diseases; Histocompatibility Antigens; Humans; Major Histocompatibility Complex; Receptors, Antigen, T-Cell
PubMed: 35967436
DOI: 10.3389/fimmu.2022.968432 -
Proteomics Nov 2021In recent decades, antibodies (Abs) have attracted the attention of academia and the biopharmaceutical industry due to their therapeutic properties and versatility in...
In recent decades, antibodies (Abs) have attracted the attention of academia and the biopharmaceutical industry due to their therapeutic properties and versatility in binding a vast spectrum of antigens. Different engineering strategies have been developed for optimizing Ab specificity, efficacy, affinity, stability and production, enabling systematic screening and analysis procedures for selecting lead candidates. This quality assessment is critical but usually demands time-consuming and labor-intensive purification procedures. Here, we harnessed the direct-mass spectrometry (direct-MS) approach, in which the analysis is carried out directly from the crude growth media, for the rapid, structural characterization of designed Abs. We demonstrate that properties such as stability, specificity and interactions with antigens can be defined, without the need for prior purification.
Topics: Antibodies; Antigens; Mass Spectrometry
PubMed: 34310051
DOI: 10.1002/pmic.202000300 -
Transplant Immunology Aug 2021Xenotransplantation, using genetically-modified pigs for clinical organ transplantation, is a solution to the organ shortage. The biggest barrier to clinical... (Review)
Review
Xenotransplantation, using genetically-modified pigs for clinical organ transplantation, is a solution to the organ shortage. The biggest barrier to clinical implementation is the antigenicity of pig cells. Humans possess preformed antibody to pig cells that initiate antibody-mediated rejection of pig organs in primates. Advances in genetic engineering have led to the development of a pig lacking the three known glycan xenoantigens (triple-knockout [TKO] pigs). A significant number of human sera demonstrate no antibody binding to TKO pig cells. As a result of the TKO pig's low antigen expression, survival of life-supporting pig organs in immunosuppressed nonhuman primates has significantly increased, and hope has been renewed for clinical trials of xenotransplantation. It is important to understand the context in which xenotransplantation's predecessor, allotransplantation, has been successful, and the steps needed for the success of xenotransplantation. Successful allotransplantation has been based on two main immunological approaches - (i) adequate immunosuppressive therapy, and (ii) careful histocompatibility matching. In vivo studies suggest that the available immunosuppressive regimens are adequate to suppress the human anti-pig cellular response. Methods to evaluate and screen patients for the first clinical xenotransplantation trial are the next challenge. The goal of this review is to summarize the history of histocompatibility testing, and the available tools that can be utilized to determine xenograft histocompatibility.
Topics: Animals; Animals, Genetically Modified; Antibodies, Heterophile; Antigens, Heterophile; Cells, Cultured; Gene Knockout Techniques; HLA Antigens; Histocompatibility; Histocompatibility Antigens Class I; Histocompatibility Testing; Humans; Polysaccharides; Swine; Tissue and Organ Procurement; Transplantation, Heterologous
PubMed: 34015463
DOI: 10.1016/j.trim.2021.101409 -
Immunology Mar 2023Oesophageal adenocarcinoma (OAC) has a relatively poor long-term survival and limited treatment options. Promising targets for immunotherapy are short peptide...
Oesophageal adenocarcinoma (OAC) has a relatively poor long-term survival and limited treatment options. Promising targets for immunotherapy are short peptide neoantigens containing tumour mutations, presented to cytotoxic T-cells by human leucocyte antigen (HLA) molecules. Despite an association between putative neoantigen abundance and therapeutic response across cancers, immunogenic neoantigens are challenging to identify. Here we characterized the mutational and immunopeptidomic landscapes of tumours from a cohort of seven patients with OAC. We directly identified one HLA-I presented neoantigen from one patient, and report functional T-cell responses from a predicted HLA-II neoantigen in a second patient. The predicted class II neoantigen contains both HLA I and II binding motifs. Our exploratory observations are consistent with previous neoantigen studies in finding that neoantigens are rarely directly observed, and an identification success rate following prediction in the order of 10%. However, our identified putative neoantigen is capable of eliciting strong T-cell responses, emphasizing the need for improved strategies for neoantigen identification.
Topics: Humans; Antigens, Neoplasm; Adenocarcinoma; Histocompatibility Antigens Class I; T-Lymphocytes, Cytotoxic; HLA Antigens; Histocompatibility Antigens Class II; Immunotherapy
PubMed: 36111495
DOI: 10.1111/imm.13578 -
Frontiers in Immunology 2022Antibody recognition of antigens is a critical element of adaptive immunity. One key class of antibody-antigen complexes is comprised of antibodies targeting linear...
Antibody recognition of antigens is a critical element of adaptive immunity. One key class of antibody-antigen complexes is comprised of antibodies targeting linear epitopes of proteins, which in some cases are conserved elements of viruses and pathogens of relevance for vaccine design and immunotherapy. Here we report a detailed analysis of the structural and interface features of this class of complexes, based on a set of nearly 200 nonredundant high resolution antibody-peptide complex structures that were assembled from the Protein Data Bank. We found that antibody-bound peptides adopt a broad range of conformations, often displaying limited secondary structure, and that the same peptide sequence bound by different antibodies can in many cases exhibit varying conformations. Propensities of contacts with antibody loops and extent of antibody binding conformational changes were found to be broadly similar to those for antibodies in complex with larger protein antigens. However, antibody-peptide interfaces showed lower buried surface areas and fewer hydrogen bonds than antibody-protein antigen complexes, while calculated binding energy per buried interface area was found to be higher on average for antibody-peptide interfaces, likely due in part to a greater proportion of buried hydrophobic residues and higher shape complementarity. This dataset and these observations can be of use for future studies focused on this class of interactions, including predictive computational modeling efforts and the design of antibodies or epitope-based vaccine immunogens.
Topics: Antigen-Antibody Complex; Antigens; Binding Sites, Antibody; Epitopes; Models, Molecular; Peptides; Protein Conformation; Vaccines
PubMed: 35874680
DOI: 10.3389/fimmu.2022.910367 -
The Journal of Experimental Medicine Jul 2023CD28 and CTLA4 are T cell coreceptors that competitively engage B7 ligands CD80 and CD86 to control adaptive immune responses. While the role of CTLA4 in restraining...
CD28 and CTLA4 are T cell coreceptors that competitively engage B7 ligands CD80 and CD86 to control adaptive immune responses. While the role of CTLA4 in restraining CD28 costimulatory signaling is well-established, the mechanism has remained unclear. Here, we report that human T cells acquire antigen-presenting-cell (APC)-derived B7 ligands and major histocompatibility complex (MHC) via trogocytosis through CD28:B7 binding. Acquired MHC and B7 enabled T cells to autostimulate, and this process was limited cell-intrinsically by CTLA4, which depletes B7 ligands trogocytosed or endogenously expressed by T cells through cis-endocytosis. Extending this model to the previously proposed extrinsic function of CTLA4 in human regulatory T cells (Treg), we show that blockade of either CD28 or CTLA4 attenuates Treg-mediated depletion of APC B7, indicating that trogocytosis and CTLA4-mediated cis-endocytosis work together to deplete B7 from APCs. Our study establishes CTLA4 as a cell-intrinsic molecular sink that limits B7 availability on the surface of T cells, with implications for CTLA4-targeted therapy.
Topics: Humans; CTLA-4 Antigen; CD28 Antigens; Antigens, CD; Ligands; Antigens, Differentiation; Abatacept; B7-2 Antigen; Membrane Glycoproteins; Immunoconjugates; B7-1 Antigen; Cell Adhesion Molecules
PubMed: 37042938
DOI: 10.1084/jem.20221391 -
Frontiers in Immunology 2020The development of allergic disease involves the production of IgE antibodies upon allergen exposure in a process called sensitization. IgE binds to receptors on the... (Review)
Review
The development of allergic disease involves the production of IgE antibodies upon allergen exposure in a process called sensitization. IgE binds to receptors on the surface of mast cells and basophils, and subsequent allergen exposure leads to cross-linking of IgE antibodies and release of cell mediators that cause allergy symptoms. Although this process is quite well-understood, very little is known about the epitopes on the allergen recognized by IgE, despite the importance of the allergen-antibody interaction for the allergic response to occur. This review discusses efforts to analyze allergen-antibody interactions, from the original epitope mapping studies using linear peptides or recombinant allergen fragments, to more sophisticated technologies, such as X-ray crystallography and nuclear magnetic resonance. These state-of-the-art approaches, combined with site-directed mutagenesis, have led to the identification of conformational IgE epitopes. The first structures of an allergen (egg lysozyme) in complex with Fab fragments from IgG antibodies were determined in the 1980s. Since then, IgG has been used as surrogate for IgE, due to the difficulty of obtaining monoclonal IgE antibodies. Technical developments including phage display libraries have contributed to progress in epitope mapping thanks to the isolation of IgE antibody constructs from combinatorial libraries made from peripheral blood mononuclear cells of allergic donors. Most recently, single B cell antibody sequencing and human hybridomas are new breakthrough technologies for finally obtaining human IgE monoclonal antibodies, ideal for epitope mapping. The information on antigenic determinants will facilitate the design of hypoallergens for immunotherapy and the investigation of the fundamental mechanisms of the IgE response.
Topics: Allergens; Animals; Antibodies; Antigen-Antibody Complex; Antigen-Antibody Reactions; Crystallography, X-Ray; Epitope Mapping; Epitopes; Humans; Immunoglobulin E; Magnetic Resonance Spectroscopy; Models, Molecular; Protein Binding; Structure-Activity Relationship
PubMed: 32983155
DOI: 10.3389/fimmu.2020.02067