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Communications Biology Nov 2021Plasmodium falciparum-infected erythrocytes (IE) sequester in the placenta via surface protein VAR2CSA, which binds chondroitin sulfate A (CSA) expressed on the...
Plasmodium falciparum-infected erythrocytes (IE) sequester in the placenta via surface protein VAR2CSA, which binds chondroitin sulfate A (CSA) expressed on the syncytiotrophoblast surface, causing placental malaria (PM) and severe adverse outcomes in mothers and their offspring. VAR2CSA belongs to the PfEMP1 variant surface antigen family; PfEMP1 proteins mediate IE adhesion and facilitate parasite immunoevasion through antigenic variation. Here we produced deglycosylated (native-like) and glycosylated versions of seven recombinant full-length VAR2CSA ectodomains and compared them for antigenicity and adhesiveness. All VAR2CSA recombinants bound CSA with nanomolar affinity, and plasma from Malian pregnant women demonstrated antigen-specific reactivity that increased with gravidity and trimester. However, allelic and glycosylation variants differed in their affinity to CSA and their serum reactivities. Deglycosylated proteins (native-like) showed higher CSA affinity than glycosylated proteins for all variants except NF54. Further, the gravidity-related increase in serum VAR2CSA reactivity (correlates with acquisition of protective immunity) was absent with the deglycosylated form of atypical M200101 VAR2CSA with an extended C-terminal region. Our findings indicate significant inter-allelic differences in adhesion and seroreactivity that may contribute to the heterogeneity of clinical presentations, which could have implications for vaccine design.
Topics: Antigens, Protozoan; Female; Humans; Immunogenicity, Vaccine; Malaria Vaccines; Malaria, Falciparum; Placenta; Plasmodium falciparum; Pregnancy; Protein Binding
PubMed: 34799664
DOI: 10.1038/s42003-021-02787-7 -
Cancer Immunology Research Aug 2018Programmed death ligand 1 (PD-L1)-mediated immunosuppression regulates peripheral tolerance and is often co-opted by tumors to evade immune attack. PD-L1 binds to PD-1...
Programmed death ligand 1 (PD-L1)-mediated immunosuppression regulates peripheral tolerance and is often co-opted by tumors to evade immune attack. PD-L1 binds to PD-1 but also binds to B7-1 (CD80) to regulate T-cell function. The binding interaction of PD-L1 with B7-1 and its functional role need further investigation to understand differences between PD-1 and PD-L1 tumor immunotherapy. We examined the molecular orientation of PD-L1 binding to B7-1 using cell-to-cell binding assays, ELISA, and flow cytometry. As expected, PD-L1-transfected cells bound to PD-1-transfected cells, and B7-1 cells bound to CD28 or CTLA-4-transfected cells; however, PD-L1 cells did not bind to B7-1 cells. By ELISA and flow cytometry with purified proteins, we found PD-L1 and B7-1 had a strong binding interaction only when PD-L1 was flexible. Soluble PD-1 and B7-1 competed for binding to PD-L1. Binding of native PD-L1 and B7-1 on the same cell surface was demonstrated with NanoBiT proximity assays. Thus, PD-L1-B7-1 interaction can occur on the same cell but not between two cells, which suggests a model in which PD-L1 can bend via its 11-amino acid, flexible stalk to bind to B7-1 , in a manner that can competitively block the binding of PD-L1 to PD-1 or of B7-1 to CD28. This binding orientation emphasizes the functional importance of coexpression of PD-L1 and B7-1 on the same cell. We found such coexpression on tumor-infiltrating myeloid cells. Our findings may help better utilize these pathways in cancer immunotherapy. .
Topics: Animals; B7-1 Antigen; B7-H1 Antigen; Binding Sites; Binding, Competitive; CD28 Antigens; CTLA-4 Antigen; Colonic Neoplasms; Mice; Models, Immunological; Myeloid Cells; Programmed Cell Death 1 Receptor
PubMed: 29871885
DOI: 10.1158/2326-6066.CIR-17-0316 -
MBio May 2018Emerging zoonotic viral diseases remain a challenge to global public health. Recent surveillance studies have implicated bats as potential reservoirs for a number of...
Emerging zoonotic viral diseases remain a challenge to global public health. Recent surveillance studies have implicated bats as potential reservoirs for a number of viral pathogens, including coronaviruses and Ebola viruses. represent a major viral family contributing to emerging diseases in both human and animal populations and have been recently identified in bats. In this study, we blended metagenomics, phylogenetics, homology modeling, and assays to characterize two novel bat calicivirus (BtCalV) capsid sequences, corresponding to strain BtCalV/A10/USA/2009, identified in near Little Orleans, MD, and bat norovirus. We observed that bat norovirus formed virus-like particles and had epitopes and receptor-binding patterns similar to those of human noroviruses. To determine whether these observations stretch across multiple bat caliciviruses, we characterized a novel bat calicivirus, BtCalV/A10/USA/2009. Phylogenetic analysis revealed that BtCalV/A10/USA/2009 likely represents a novel genus and is most closely related to "recoviruses." Homology modeling revealed that the capsid sequences of BtCalV/A10/USA/2009 and bat norovirus resembled human norovirus capsid sequences and retained host ligand binding within the receptor-binding domains similar to that seen with human noroviruses. Both caliciviruses bound histo-blood group antigens in patterns that overlapped those seen with human and animal noroviruses. Taken together, our results indicate the potential for bat caliciviruses to bind histo-blood group antigens and overcome a significant barrier to cross-species transmission. Additionally, we have shown that bat norovirus maintains antigenic epitopes similar to those seen with human noroviruses, providing further evidence of evolutionary descent. Our results reiterate the importance of surveillance of wild-animal populations, especially of bats, for novel viral pathogens. Caliciviruses are rapidly evolving viruses that cause pandemic outbreaks associated with significant morbidity and mortality globally. The animal reservoirs for human caliciviruses are unknown; bats represent critical reservoir species for several emerging and zoonotic diseases. Recent reports have identified several bat caliciviruses but have not characterized biological functions associated with disease risk, including their potential emergence in other mammalian populations. In this report, we identified a novel bat calicivirus that is most closely related to nonhuman primate caliciviruses. Using this new bat calicivirus and a second norovirus-like bat calicivirus capsid gene sequence, we generated virus-like particles that have host carbohydrate ligand binding patterns similar to those of human and animal noroviruses and that share antigens with human noroviruses. The similarities to human noroviruses with respect to binding patterns and antigenic epitopes illustrate the potential for bat caliciviruses to emerge in other species and the importance of pathogen surveillance in wild-animal populations.
Topics: Animals; Antigens, Viral; Blood Group Antigens; Caliciviridae; Caliciviridae Infections; Capsid Proteins; Chiroptera; Humans; Norovirus; Phylogeny; Protein Domains
PubMed: 29789360
DOI: 10.1128/mBio.00869-18 -
Biosensors & Bioelectronics Sep 2019The ability of influenza viruses to rapidly evolve has caused significant challenges in viral surveillance, diagnosis, and therapeutic development. Molecular sequencing... (Review)
Review
The ability of influenza viruses to rapidly evolve has caused significant challenges in viral surveillance, diagnosis, and therapeutic development. Molecular sequencing methods, though powerful tools for monitoring influenza evolution at the genetic level, are not able to fully characterize the antigenic properties of influenza viruses. Understanding influenza virus antigenicity is critical to vaccine development and disease prevention. Traditional immunoassays which have been widely used for evaluating influenza antigenicity have limited throughput. To alleviate these problems, new bioanalytical tools to investigate influenza antigenicity by measuring antibody-antigen binding are an active area of research. Herein, we review immunosensor technologies from the aspects of various sensing principles, while highlighting recent developments in multiplex, label-free detection strategies. Highlighted technologies include electrochemical immunosensors relying on impedimetric detection; these demonstrate simple design and cost effectiveness for mass production. Antibody arrays implemented on an optical interferometric sensor system allow systematic characterization of influenza antigenicity. Quartz microbalance immunosensors are highly sensitive but have yet to be explored for multiplex sensing. Immunosensors made on lateral flow strips have shown promise in rapid diagnosis of influenza subtypes. We anticipate that these and other technologies discussed in the review will facilitate advances in the study of influenza, and other viral pathogens.
Topics: Animals; Antigens, Viral; Biosensing Techniques; Equipment Design; Humans; Immunoassay; Influenza, Human; Alphainfluenzavirus; Orthomyxoviridae; Orthomyxoviridae Infections
PubMed: 31272058
DOI: 10.1016/j.bios.2019.111476 -
Human Vaccines & Immunotherapeutics Feb 2017Neisseria meningitidis serogroup B (MenB) is an important cause of invasive meningococcal disease. The development of safe and effective vaccines with activity across... (Review)
Review
Neisseria meningitidis serogroup B (MenB) is an important cause of invasive meningococcal disease. The development of safe and effective vaccines with activity across the diversity of MenB strains has been challenging. While capsular polysaccharide conjugate vaccines have been highly successful in the prevention of disease due to meningococcal serogroups A, C, W, and Y, this approach has not been possible for MenB owing to the poor immunogenicity of the MenB capsular polysaccharide. Vaccines based on outer membrane vesicles have been successful in the prevention of invasive MenB disease caused by the single epidemic strain from which they were derived, but they do not confer broad protection against diverse MenB strains. Thus, alternative approaches to vaccine development have been pursued to identify vaccine antigens that can provide broad protection against the epidemiologic and antigenic diversity of invasive MenB strains. Human factor H binding protein (fHBP) was found to be such an antigen, as it is expressed on nearly all invasive disease strains of MenB and can induce bactericidal responses against diverse MenB strains. A bivalent vaccine (Trumenba®, MenB-FHbp, bivalent rLP2086) composed of equal amounts of 2 fHBP variants from each of the 2 immunologically diverse subfamilies of fHBP (subfamilies A and B) was the first MenB vaccine licensed in the United States under an accelerated approval pathway for prevention of invasive MenB disease. Due to the relatively low incidence of meningococcal disease, demonstration of vaccine efficacy for the purposes of licensure of bivalent rLP2086 was based on vaccine-elicited bactericidal activity as a surrogate marker of efficacy, as measured in vitro by the serum bactericidal assay using human complement. Because bacterial surface proteins such as fHBP are antigenically variable, an important component for evaluation and licensure of bivalent rLP2086 included stringent criteria for assessment of breadth of coverage across antigenically diverse and epidemiologically important MenB strains. This review describes the rigorous approach used to assess broad coverage of bivalent rLP2086. Alternative nonfunctional assays proposed for assessing vaccine coverage are also discussed.
Topics: Antibodies, Bacterial; Antigens, Bacterial; Bacterial Proteins; Blood Bactericidal Activity; Cross Reactions; Drug Approval; Humans; Meningitis, Meningococcal; Meningococcal Vaccines; Neisseria meningitidis, Serogroup B; United States; Vaccines, Synthetic
PubMed: 27960595
DOI: 10.1080/21645515.2017.1264750 -
Biological Chemistry Sep 2015The adaptive immune system co-evolved with sophisticated pathways of antigen processing for efficient clearance of viral infections and malignant transformation.... (Review)
Review
The adaptive immune system co-evolved with sophisticated pathways of antigen processing for efficient clearance of viral infections and malignant transformation. Antigenic peptides are primarily generated by proteasomal degradation and translocated into the lumen of the endoplasmic reticulum (ER) by the transporter associated with antigen processing (TAP). In the ER, peptides are loaded onto major histocompatibility complex I (MHC I) molecules orchestrated by a multisubunit peptide-loading complex (PLC). Peptide-MHC I complexes are targeted to the cell surface for antigen presentation to cytotoxic T cells, which eventually leads to the elimination of virally infected or malignantly transformed cells. Here, we review MHC I mediated antigen processing with a primary focus on the function and structural organization of the heterodimeric ATP-binding cassette (ABC) transporter TAP1/2. We discuss recent data on the molecular transport mechanism of the antigen translocation complex with respect to structural and biochemical information of other ABC exporters. We further summarize how TAP provides a scaffold for the assembly of the macromolecular PLC, thereby coupling peptide translocation with MHC I loading. TAP inhibition by distinct viral evasins highlights the important role of TAP in adaptive immunity.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 2; ATP Binding Cassette Transporter, Subfamily B, Member 3; ATP-Binding Cassette Transporters; Adaptive Immunity; Antigens; Histocompatibility Antigens Class I; Humans
PubMed: 25781678
DOI: 10.1515/hsz-2014-0320 -
Frontiers in Immunology 2018Alloreactivity compromising clinical outcomes in stem cell transplantation is observed despite HLA matching of donors and recipients. This has its origin in the... (Review)
Review
Alloreactivity compromising clinical outcomes in stem cell transplantation is observed despite HLA matching of donors and recipients. This has its origin in the variation between the exomes of the two, which provides the basis for minor histocompatibility antigens (mHA). The mHA presented on the HLA class I and II molecules and the ensuing T cell response to these antigens results in graft vs. host disease. In this paper, results of a whole exome sequencing study are presented, with resulting alloreactive polymorphic peptides and their HLA class I and HLA class II (DRB1) binding affinity quantified. Large libraries of potentially alloreactive recipient peptides binding both sets of molecules were identified, with HLA-DRB1 generally presenting a greater number of peptides. These results are used to develop a quantitative framework to understand the immunobiology of transplantation. A tensor-based approach is used to derive the equations needed to determine the alloreactive donor T cell response from the mHA-HLA binding affinity and protein expression data. This approach may be used in future studies to simulate the magnitude of expected donor T cell response and determine the risk for alloreactive complications in HLA matched or mismatched hematopoietic cell and solid organ transplantation.
Topics: Algorithms; Antigen Presentation; Antigen-Presenting Cells; Antigens; Graft vs Host Disease; HLA Antigens; Histocompatibility; Humans; Isoantigens; Models, Theoretical; Peptides; Protein Binding; Stem Cell Transplantation; T-Lymphocytes; Tissue Donors
PubMed: 30364159
DOI: 10.3389/fimmu.2018.02284 -
Proceedings of the National Academy of... Apr 2024The ability to selectively bind to antigenic peptides and secrete effector molecules can define rare and low-affinity populations of cells with therapeutic potential in...
The ability to selectively bind to antigenic peptides and secrete effector molecules can define rare and low-affinity populations of cells with therapeutic potential in emerging T cell receptor (TCR) immunotherapies. We leverage cavity-containing hydrogel microparticles, called nanovials, each coated with peptide-major histocompatibility complex (pMHC) monomers to isolate antigen-reactive T cells. T cells are captured and activated by pMHCs inducing the secretion of effector molecules including IFN-γ and granzyme B that are accumulated on nanovials, allowing sorting based on both binding and function. The TCRs of sorted cells on nanovials are sequenced, recovering paired αβ-chains using microfluidic emulsion-based single-cell sequencing. By labeling nanovials having different pMHCs with unique oligonucleotide-barcodes and secretions with oligo-barcoded detection antibodies, we could accurately link TCR sequences to specific targets and rank each TCR based on the corresponding cell's secretion level. Using the technique, we identified an expanded repertoire of functional TCRs targeting viral antigens with high specificity and found rare TCRs with activity against cancer-specific splicing-enhanced epitopes.
Topics: Receptors, Antigen, T-Cell; T-Lymphocytes; Peptides; Histocompatibility Antigens; Antigens
PubMed: 38536748
DOI: 10.1073/pnas.2320442121 -
Biochimica Et Biophysica Acta.... May 2023Invariant natural killer T cells (iNKT cells) can be activated through binding antigenic lipid/CD1d complexes to their TCR. Antigenic lipids are processed, loaded, and... (Review)
Review
Invariant natural killer T cells (iNKT cells) can be activated through binding antigenic lipid/CD1d complexes to their TCR. Antigenic lipids are processed, loaded, and displayed in complex with CD1d by lipid antigen presenting cells (LAPCs). The mechanism of lipid antigen presentation via CD1d is highly conserved with recent work showing adipocytes are LAPCs that, besides having a role in lipid storage, can activate iNKT cells and play an important role in systemic metabolic disease. Recent studies shed light on parameters potentially dictating cytokine output and how obesity-associated metabolic disease may affect such parameters. By following a lipid antigen's journey, we identify five key areas which may dictate cytokine skew: co-stimulation, structural properties of the lipid antigen, stability of lipid antigen/CD1d complexes, intracellular and extracellular pH, and intracellular and extracellular lipid environment. Recent publications indicate that the combination of advanced omics-type approaches and machine learning may be a fruitful way to interconnect these 5 areas, with the ultimate goal to provide new insights for therapeutic exploration.
Topics: Adipocytes; Antigen Presentation; Cytokines; Lipids; Natural Killer T-Cells; Antigens, CD1d
PubMed: 36773690
DOI: 10.1016/j.bbalip.2023.159292 -
Frontiers in Immunology 2022The dynamic interplay between virus and host plays out across many interacting surfaces as virus and host evolve continually in response to one another. In particular,... (Review)
Review
The dynamic interplay between virus and host plays out across many interacting surfaces as virus and host evolve continually in response to one another. In particular, epitope-paratope interactions (EPIs) between viral antigen and host antibodies drive much of this evolutionary race. In this review, we describe a series of recent studies examining aspects of epitope complexity that go beyond two interacting protein surfaces as EPIs are typically understood. To structure our discussion, we present a framework for understanding epitope complexity as a spectrum along a series of axes, focusing primarily on 1) epitope biochemical complexity (e.g., epitopes involving N-glycans) and 2) antigen conformational/dynamic complexity (e.g., epitopes with differential properties depending on antigen state or fold-axis). We highlight additional epitope complexity factors including epitope tertiary/quaternary structure, which contribute to epistatic relationships between epitope residues within- or adjacent-to a given epitope, as well as epitope overlap resulting from polyclonal antibody responses, which is relevant when assessing antigenic pressure against a given epitope. Finally, we discuss how these different forms of epitope complexity can limit EPI analyses and therapeutic antibody development, as well as recent efforts to overcome these limitations.
Topics: Antibodies; Antigens, Viral; Binding Sites, Antibody; Epitopes; Vaccines
PubMed: 35784339
DOI: 10.3389/fimmu.2022.904609