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1.
Sci Rep ; 14(1): 8587, 2024 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-38615147

RESUMO

Helicobacter pylori infects approximately half the human population and has an unusual infective niche of the human stomach. Helicobacter pylori is a major cause of gastritis and has been classified as a group 1 carcinogen by the WHO. Treatment involves triple or quadruple antibiotic therapy, but antibiotic resistance is becoming increasingly prevalent. Helicobacter pylori expresses certain blood group related antigens (Lewis system) as a part of its lipopolysaccharide (LPS), which is thought to assist in immune evasion. Additionally, H. pylori LPS participates in adhesion to host cells alongside several adhesion proteins. This study profiled the carbohydrates of H. pylori reference strains (SS1 and 26695) using monoclonal antibodies (mAbs) and lectins, identifying interactions between two carbohydrate-targeting mAbs and multiple lectins. Atomic force microscopy (AFM) scans were used to probe lectin and antibody interactions with the bacterial surfaces. The selected mAb and lectins displayed an increased adhesive force over the surface of the curved H. pylori rods. Furthermore, this study demonstrates the ability of anti-carbohydrate antibodies to reduce the adhesion of H. pylori 26695 to human gastric adenocarcinoma cells via AFM. Targeting bacterial carbohydrates to disrupt crucial adhesion and immune evasion mechanisms represents a promising strategy for combating H. pylori infection.


Assuntos
Antígenos de Grupos Sanguíneos , Infecções por Helicobacter , Helicobacter pylori , Humanos , Lipopolissacarídeos , Polissacarídeos , Anticorpos Monoclonais , Lectinas
2.
Front Microbiol ; 14: 1065609, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37350788

RESUMO

The development of virus-like particle (VLP) based vaccines for human papillomavirus, hepatitis B and hepatitis E viruses represented a breakthrough in vaccine development. However, for dengue and COVID-19, technical complications, such as an incomplete understanding of the requirements for protective immunity, but also limitations in processes to manufacture VLP vaccines for enveloped viruses to large scale, have hampered VLP vaccine development. Selecting the right adjuvant is also an important consideration to ensure that a VLP vaccine induces protective antibody and T cell responses. For diseases like COVID-19 and dengue fever caused by RNA viruses that exist as families of viral variants with the potential to escape vaccine-induced immunity, the development of more efficacious vaccines is also necessary. Here, we describe the development and characterisation of novel VLP vaccine candidates using SARS-CoV-2 and dengue virus (DENV), containing the major viral structural proteins, as protypes for a novel approach to produce VLP vaccines. The VLPs were characterised by Western immunoblot, enzyme immunoassay, electron and atomic force microscopy, and in vitro and in vivo immunogenicity studies. Microscopy techniques showed proteins self-assemble to form VLPs authentic to native viruses. The inclusion of the glycolipid adjuvant, α-galactosylceramide (α-GalCer) in the vaccine formulation led to high levels of natural killer T (NKT) cell stimulation in vitro, and strong antibody and memory CD8+ T cell responses in vivo, demonstrated with SARS-CoV-2, hepatitis C virus (HCV) and DEN VLPs. This study shows our unique vaccine formulation presents a promising, and much needed, new vaccine platform in the fight against infections caused by enveloped RNA viruses.

3.
PLoS One ; 17(10): e0276287, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36240154

RESUMO

The blood fluke Cardicola forsteri (Trematoda: Aporocotylidae) is a pathogen of ranched bluefin tuna in Japan and Australia. Genomics of Cardicola spp. have thus far been limited to molecular phylogenetics of select gene sequences. In this study, sequencing of the C. forsteri genome was performed using Illumina short-read and Oxford Nanopore long-read technologies. The sequences were assembled de novo using a hybrid of short and long reads, which produced a high-quality contig-level assembly (N50 > 430 kb and L50 = 138). The assembly was also relatively complete and unfragmented, comprising 66% and 7.2% complete and fragmented metazoan Benchmarking Universal Single-Copy Orthologs (BUSCOs), respectively. A large portion (> 55%) of the genome was made up of intergenic repetitive elements, primarily long interspersed nuclear elements (LINEs), while protein-coding regions cover > 6%. Gene prediction identified 8,564 hypothetical polypeptides, > 77% of which are homologous to published sequences of other species. The identification of select putative proteins, including cathepsins, calpains, tetraspanins, and glycosyltransferases is discussed. This is the first genome assembly of any aporocotylid, a major step toward understanding of the biology of this family of fish blood flukes and their interactions within hosts.


Assuntos
Doenças dos Peixes , Schistosomatidae , Animais , Catepsinas , Glicosiltransferases , Schistosoma , Atum/genética
4.
Front Immunol ; 13: 868225, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35634347

RESUMO

Helicobacter pylori is an important human pathogen that infects half the human population and can lead to significant clinical outcomes such as acute and chronic gastritis, duodenal ulcer, and gastric adenocarcinoma. To establish infection, H. pylori employs several mechanisms to overcome the innate and adaptive immune systems. H. pylori can modulate interleukin (IL) secretion and innate immune cell function by the action of several virulence factors such as VacA, CagA and the type IV secretion system. Additionally, H. pylori can modulate local dendritic cells (DC) negatively impacting the function of these cells, reducing the secretion of immune signaling molecules, and influencing the differentiation of CD4+ T helper cells causing a bias to Th1 type cells. Furthermore, the lipopolysaccharide (LPS) of H. pylori displays a high degree of phase variation and contains human blood group carbohydrate determinants such as the Lewis system antigens, which are proposed to be involved in molecular mimicry of the host. Lastly, the H. pylori group of outer membrane proteins such as BabA play an important role in attachment and interaction with host Lewis and other carbohydrate antigens. This review examines the various mechanisms that H. pylori utilises to evade the innate immune system as well as discussing how the structure of the H. pylori LPS plays a role in immune evasion.


Assuntos
Infecções por Helicobacter , Helicobacter pylori , Humanos , Evasão da Resposta Imune , Lipopolissacarídeos , Fatores de Virulência/metabolismo
5.
Biochem J ; 477(17): 3219-3235, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32789497

RESUMO

Immunotherapy has been successful in treating many tumour types. The development of additional tumour-antigen binding monoclonal antibodies (mAbs) will help expand the range of immunotherapeutic targets. Lewis histo-blood group and related glycans are overexpressed on many carcinomas, including those of the colon, lung, breast, prostate and ovary, and can therefore be selectively targeted by mAbs. Here we examine the molecular and structural basis for recognition of extended Lea and Lex containing glycans by a chimeric mAb. Both the murine (FG88.2) IgG3 and a chimeric (ch88.2) IgG1 mAb variants showed reactivity to colorectal cancer cells leading to significantly reduced cell viability. We determined the X-ray structure of the unliganded ch88.2 fragment antigen-binding (Fab) containing two Fabs in the unit cell. A combination of molecular docking, glycan grafting and molecular dynamics simulations predicts two distinct subsites for recognition of Lea and Lex trisaccharides. While light chain residues were exclusively used for Lea binding, recognition of Lex involved both light and heavy chain residues. An extended groove is predicted to accommodate the Lea-Lex hexasaccharide with adjoining subsites for each trisaccharide. The molecular and structural details of the ch88.2 mAb presented here provide insight into its cross-reactivity for various Lea and Lex containing glycans. Furthermore, the predicted interactions with extended epitopes likely explains the selectivity of this antibody for targeting Lewis-positive tumours.


Assuntos
Anticorpos Monoclonais Murinos , Antineoplásicos Imunológicos , Fragmentos Fab das Imunoglobulinas , Antígenos do Grupo Sanguíneo de Lewis , Antígenos CD15 , Simulação de Acoplamento Molecular , Neoplasias , Oligossacarídeos , Animais , Anticorpos Monoclonais Murinos/química , Anticorpos Monoclonais Murinos/imunologia , Antineoplásicos Imunológicos/química , Antineoplásicos Imunológicos/imunologia , Linhagem Celular Tumoral , Humanos , Fragmentos Fab das Imunoglobulinas/química , Fragmentos Fab das Imunoglobulinas/imunologia , Antígenos do Grupo Sanguíneo de Lewis/química , Antígenos do Grupo Sanguíneo de Lewis/imunologia , Antígenos CD15/química , Antígenos CD15/imunologia , Camundongos , Neoplasias/química , Neoplasias/imunologia , Oligossacarídeos/química , Oligossacarídeos/imunologia
6.
J Biol Chem ; 295(4): 1009-1020, 2020 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-31831622

RESUMO

Cancer remains a leading cause of morbidity and mortality worldwide, requiring ongoing development of targeted therapeutics such as monoclonal antibodies. Carbohydrates on embryonic cells are often highly expressed in cancer and are therefore attractive targets for antibodies. Stage-specific embryonic antigen-4 (SSEA-4) is one such glycolipid target expressed in many cancers, including breast and ovarian carcinomas. Here, we defined the structural basis for recognition of SSEA-4 by a novel monospecific chimeric antibody (ch28/11). Five X-ray structures of ch28/11 Fab complexes with the SSEA-4 glycan headgroup, determined at 1.5-2.7 Å resolutions, displayed highly similar three-dimensional structures indicating a stable binding mode. The structures also revealed that by adopting a horseshoe-shaped conformation in a deep groove, the glycan headgroup likely sits flat against the membrane to allow the antibody to interact with SSEA-4 on cancer cells. Moreover, we found that the terminal sialic acid of SSEA-4 plays a dominant role in dictating the exquisite specificity of the ch28/11 antibody. This observation was further supported by molecular dynamics simulations of the ch28/11-glycan complex, which show that SSEA-4 is stabilized by its terminal sialic acid, unlike SSEA-3, which lacks this sialic acid modification. These high-resolution views of how a glycolipid interacts with an antibody may help to advance a new class of cancer-targeting immunotherapy.


Assuntos
Anticorpos Antineoplásicos/imunologia , Ácido N-Acetilneuramínico/metabolismo , Neoplasias/imunologia , Antígenos Embrionários Estágio-Específicos/metabolismo , Anticorpos Antineoplásicos/química , Especificidade de Anticorpos/imunologia , Configuração de Carboidratos , Humanos , Fragmentos Fab das Imunoglobulinas/metabolismo , Ligantes , Simulação de Dinâmica Molecular , Polissacarídeos/química , Polissacarídeos/metabolismo , Antígenos Embrionários Estágio-Específicos/química
7.
PLoS One ; 14(10): e0224028, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31622415

RESUMO

The cytotoxic effects of melittin, a bee-venom peptide, have been widely studied towards cancer cells. Typically, these studies have examined the effect of melittin over extended-time courses (6-24 hours), meaning that immediate cellular interactions have been overlooked. In this work, we demonstrate the rapid effects of melittin on both gastric and colorectal cancer, specifically AGS, COLO205 and HCT-15 cell lines, over a period of 15 minutes. Melittin exhibited a dose dependent effect at 4 hours of treatment, with complete cellular death occurring at the highest dose of 20 µg/mL. Interestingly, when observed at shorter time points, melittin induced cellular changes within seconds; membrane damage was observed as swelling, breakage or blebbing. High-resolution imaging revealed treated cells to be compromised, showing clear change in cellular morphology. After 1 minute of melittin treatment, membrane changes were observed, and intracellular material could be seen expelled from the cells. Overall, these results enhance our understanding of the fast acting anti-cancer effects of melittin.


Assuntos
Antineoplásicos/farmacologia , Membrana Celular/efeitos dos fármacos , Meliteno/farmacologia , Apoptose/efeitos dos fármacos , Venenos de Abelha/farmacologia , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Humanos , Microscopia de Força Atômica , Microscopia de Fluorescência , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/patologia
8.
J Colloid Interface Sci ; 545: 259-268, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30897421

RESUMO

Hepatitis C virus-like particles (VLPs) are being developed as a quadrivalent vaccine candidate, eliciting both humoral and cellular immune responses in animal trials. Biophysical, biomechanical and biochemical properties are important for virus and VLP interactions with host cells and recognition by the immune system. Atomic force microscopy (AFM) is a powerful tool for visualizing surface topographies of cells, bionanoparticles and biomolecules, and for determining biophysical and biomechanical attributes such as size and elasticity. In this work, AFM was used to define morphological and nanomechanical properties of VLPs representing four common genotypes of hepatitis C virus. Significant differences in size of the VLPs were observed, and particles demonstrated a wide range of elasticity. Ordered packing of the core and potentially envelope glycoproteins was observed on the surfaces of the VLPs, but detailed structural characterization was hindered due to intrinsic dynamic fluctuations or AFM probe-induced damage of the VLPs. All VLPs were shown to be glycosylated in a manner similar to native viral particles. Together, the results presented in this study further our understanding of the nanostructure of hepatitis C VLPs, and should influence their uptake as viable vaccine candidates.


Assuntos
Nanopartículas/metabolismo , Vacinas contra Hepatite Viral/metabolismo , Vírion/metabolismo , Transporte Biológico , Proteínas de Transporte/metabolismo , Linhagem Celular , Elasticidade , Genótipo , Hepacivirus/metabolismo , Humanos , Lectinas/química , Lectinas/metabolismo , Microscopia de Força Atômica/métodos , Nanopartículas/química , Tamanho da Partícula , Propriedades de Superfície , Proteínas do Envelope Viral/metabolismo , Vacinas contra Hepatite Viral/química , Vírion/química
9.
J Biochem ; 165(3): 239-248, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30476118

RESUMO

In order to facilitate a number of processes including nutrient acquisition and immune evasion, malaria parasites extensively remodel their host erythrocyte. This remodelling is to a large extent accomplished through protein export, a crucial process mediated by the Plasmodium translocon for exported proteins (PTEX) translocon which is comprised of three core components, HSP101, PTEX150 and EXP2. EXP2 has been structurally and electrophysiologically shown to form the pore that spans the vacuole membrane enveloping the parasite. Here, we biochemically investigate the structure and function of EXP2. By differential alkylation we provide direct evidence that cysteines C113 and C140 form an intramolecular disulphide bond, while C201 is predominantly in a reduced state. We demonstrate that EXP2 possesses a protease resistant, membrane-associated, N-terminal region of ∼20 kDa that does not project into the infected erythrocyte cytosol; however, its C-terminus does project into the vacuole space. We show that a putative transmembrane peptide derived from the N-terminal region of EXP2 is haemolytic and in a polymer-based osmotic protection assay, we demonstrate that this peptide forms a discrete haemolytic pore. This work provides further biochemical insight into the role, function and cellular arrangement of EXP2 as the pore-forming component for protein translocation.


Assuntos
Complexos Multiproteicos/metabolismo , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Espectrometria de Massas , Transporte Proteico
10.
J Chem Inf Model ; 58(9): 1976-1989, 2018 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-30075071

RESUMO

Bacterial adhesion to human epithelia via lectins constitutes a therapeutic opportunity to prevent infection. Specifically, BambL (the lectin from Burkholderia ambifaria) is implicated in cystic fibrosis, where lectin-mediated bacterial adhesion to fucosylated lung epithelia is suspected to play an important role. We employed structure-based virtual screening to identify inhibitors of BambL-saccharide interaction with potential therapeutic value. To enable such discovery, a virtual screening protocol was iteratively developed via 194 retrospective screening protocols against 4 bacterial lectins (BambL, BC2L-A, FimH, and LecA) with known ligands. Specific attention was given to the rigorous evaluation of retrospective screening, including calculation of analytical errors for enrichment metrics. The developed virtual screening workflow used crystallographic constraints, pharmacophore filters, and a final manual selection step. The protocol was applied to BambL, predicting 15 active compounds from virtual libraries of approximately 7 million compounds. Experimental validation using fluorescence polarization confirmed micromolar inhibitory activity for two compounds, which were further characterized by isothermal titration calorimetry and surface plasmon resonance. Subsequent testing against LecB from Pseudomonas aeruginosa demonstrated binding specificity of one of the hit compounds. This report demonstrates the utility of virtual screening protocols, integrating ligand-based pharmacophore filtering and structure-based constraints, in the search for bacterial lectin inhibitors.


Assuntos
Proteínas de Bactérias/química , Burkholderia/metabolismo , Lectinas/química , Lectinas/metabolismo , Receptores de Superfície Celular/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Modelos Moleculares , Conformação Proteica , Pseudomonas aeruginosa , Receptores de Superfície Celular/metabolismo , Bibliotecas de Moléculas Pequenas
11.
Biochem J ; 475(13): 2179-2190, 2018 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-29794155

RESUMO

Antibody engineering is important for many diagnostic and clinical applications of monoclonal antibodies. We recently reported a series of fragment crystallizable (Fc) mutations targeting the neonatal Fc receptor (FcRn) site on a Lewis Y (Ley) binding IgG1, hu3S193. The hu3S193 variants displayed shortened in vivo half-lives and may have potential for radioimaging or radiotherapy of Ley-positive tumors. Here, we report Fc crystal structures of wild-type hu3S193, seven FcRn-binding site variants, and a variant lacking C1q binding or complement-dependent cytotoxicity (CDC) activity. The Fc conformation of the FcRn-binding sites was similar for wild-type and all mutants of hu3S193 Fc, which suggests that FcRn interactions were directly affected by the amino acid substitutions. The C1q-binding site mutant Fc was nearly identical with the wild-type Fc. Surprisingly, several hu3S193 Fc variants showed large changes in global structure compared with wild-type Fc. All hu3S193 Fc mutants had similar antibody-dependent cellular cytotoxicity, despite some with conformations expected to diminish Fc gamma receptor binding. Several hu3S193 variants displayed altered CDC, but there was no correlation with the different Fc conformations. All versions of hu3S193, except the C1q-binding site mutant, bound C1q, suggesting that the altered CDC of some variants could result from different propensities to form IgG hexamers after engaging Ley on target cells. Overall, our findings support the concept that the antibody Fc is both flexible and mobile in solution. Structure-based design approaches should take into account the conformational plasticity of the Fc when engineering antibodies with optimal effector properties.


Assuntos
Antígenos de Histocompatibilidade Classe I/química , Fragmentos Fc das Imunoglobulinas/química , Imunoglobulina G/química , Mutação , Receptores Fc/química , Citotoxicidade Celular Dependente de Anticorpos , Sítios de Ligação , Complemento C1q/química , Complemento C1q/genética , Complemento C1q/metabolismo , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Fragmentos Fc das Imunoglobulinas/genética , Fragmentos Fc das Imunoglobulinas/imunologia , Imunoglobulina G/genética , Imunoglobulina G/imunologia , Receptores Fc/genética , Receptores Fc/imunologia
12.
Front Pharmacol ; 8: 393, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28680402

RESUMO

Burkholderia ambifaria is an opportunistic respiratory pathogen belonging to the Burkholderia cepacia complex, a collection of species responsible for the rapidly fatal cepacia syndrome in cystic fibrosis patients. A fucose-binding lectin identified in the B. ambifaria genome, BambL, is able to adhere to lung tissue, and may play a role in respiratory infection. X-ray crystallography has revealed the bound complex structures for four fucosylated human blood group epitopes (blood group B, H type 1, H type 2, and Lex determinants). The present study employed computational approaches, including docking and molecular dynamics (MD), to extend the structural analysis of BambL-oligosaccharide complexes to include four additional blood group saccharides (A, Lea, Leb, and Ley) and a library of blood-group-related carbohydrates. Carbohydrate recognition is dominated by interactions with fucose via a hydrogen-bonding network involving Arg15, Glu26, Ala38, and Trp79 and a stacking interaction with Trp74. Additional hydrogen bonds to non-fucose residues are formed with Asp30, Tyr35, Thr36, and Trp74. BambL recognition is dominated by interactions with fucose, but also features interactions with other parts of the ligands that may modulate specificity or affinity. The detailed computational characterization of the BambL carbohydrate-binding site provides guidelines for the future design of lectin inhibitors.

13.
Br J Haematol ; 177(3): 423-440, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28211573

RESUMO

We have discovered that a small cationic molecule, GW4869, is cytotoxic to a subset of myeloma cell lines and primary myeloma plasma cells. Biochemical analysis revealed that GW4869 binds to anionic phospholipids such as phosphatidylserine - a lipid normally confined to the intracellular side of the cell membrane. However, interestingly, phosphatidylserine was expressed on the surface of all myeloma cell lines tested (n = 12) and 9/15 primary myeloma samples. Notably, the level of phosphatidylserine expression correlated well with sensitivity to GW4869. Inhibition of cell surface phosphatidylserine exposure with brefeldin A resulted in resistance to GW4869. Finally, GW4869 was shown to delay the growth of phosphatidylserine-high myeloma cells in vivo. To the best of our knowledge, this is the first example of using a small molecule to target phosphatidylserine on malignant cells. This study may provide the rationale for the development of phosphatidylserine-targeting small molecules for the treatment of surface phosphatidylserine-expressing cancers.


Assuntos
Compostos de Anilina/farmacologia , Antineoplásicos/farmacologia , Compostos de Benzilideno/farmacologia , Mieloma Múltiplo/tratamento farmacológico , Mieloma Múltiplo/metabolismo , Fosfatidilserinas/metabolismo , Compostos de Anilina/administração & dosagem , Compostos de Anilina/uso terapêutico , Animais , Antineoplásicos/administração & dosagem , Antineoplásicos/uso terapêutico , Compostos de Benzilideno/administração & dosagem , Compostos de Benzilideno/uso terapêutico , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Humanos , Camundongos SCID , Mieloma Múltiplo/patologia , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
14.
Curr Opin Struct Biol ; 44: 1-8, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-27821276

RESUMO

Carbohydrate-binding antibodies and carbohydrate-based vaccines are being actively pursued as targeted immunotherapies for a broad range of cancers. Recognition of tumor-associated carbohydrates (glycans) by antibodies is predominantly towards terminal epitopes on glycoproteins and glycolipids on the surface of cancer cells. Crystallography along with complementary experimental and computational methods have been extensively used to dissect antibody recognition of glycan epitopes commonly found in cancer. We provide an overview of the structural biology of antibody recognition of tumor-associated glycans and propose potential rearrangements of these targets in the membrane that could dictate the complex biological activities of these antibodies against cancer cells.


Assuntos
Anticorpos/imunologia , Neoplasias/imunologia , Neoplasias/patologia , Sequência de Aminoácidos , Animais , Anticorpos/química , Epitopos/imunologia , Glicosilação , Humanos , Neoplasias/metabolismo , Polissacarídeos/imunologia , Polissacarídeos/metabolismo
15.
Mol Immunol ; 77: 113-25, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27497190

RESUMO

We discovered that some bovine antibodies are amongst the largest known to exist due to the presence of an exceptionally long CDR3H (≥49 amino acids) with multiple cysteines that provide a unique knob and stalk structure to the antigen binding site. The large CDR3H size, unlike mouse and human, provides a suitable platform for antigenization with large configurational B-epitopes. Here we report the identification of a B-epitope on the gC envelope protein of bovine herpes virus type-1 (BoHV-1) recognized by a bovine IgG1 antibody. The identified 156 amino acid long gC fragment (gC156) was expressed as a recombinant protein. Subsequently, a functional scFv fragment with a 61 amino-acid long CDR3H (scFv1H12) was expressed such that gC156 was grafted into the CDR3H, replacing the "knob" region (gC156scFv1H12 or Ag-scFv). Importantly, the Ag-scFv could be recognized by a neutralizing antibody fragment (scFv3-18L), which suggests that the engraftment of gC156 into the CDR3H of 1H12 maintained the native conformation of the BoHV-1 B-epitope. A 3D model of gC156 was generated using fold-recognition approaches and this was grafted onto the CDR3H stalk of the 1H12 Fab crystal structure to predict the 3D structure of the Ag-scFv. The grafted antigen in Ag-scFv is predicted to have a compact conformation with the ability to protrude into the solvent. Upon immunization of bovine calves, the antigenized scFv (gC156scFv1H12) induced a higher antibody response as compared to free recombinant gC156. These observations suggest that antigenization of bovine scFv with an exceptionally long CDR3H provides a novel approach to developing the next generation of vaccines against infectious agents that require induction of protective humoral immunity.


Assuntos
Regiões Determinantes de Complementaridade/imunologia , Epitopos de Linfócito B/imunologia , Herpesvirus Bovino 1/imunologia , Anticorpos de Cadeia Única/imunologia , Proteínas do Envelope Viral/imunologia , Animais , Anticorpos Antivirais/imunologia , Western Blotting , Bovinos , Ensaio de Imunoadsorção Enzimática , Espectrometria de Massas , Modelos Moleculares , Reação em Cadeia da Polimerase , Proteínas Recombinantes/imunologia
16.
MAbs ; 8(4): 775-86, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27030023

RESUMO

IgG has a long half-life through engagement of its Fc region with the neonatal Fc receptor (FcRn). The FcRn binding site on IgG1 has been shown to contain I253 and H310 in the CH2 domain and H435 in the CH3 domain. Altering the half-life of IgG has been pursued with the aim to prolong or reduce the half-life of therapeutic IgGs. More recent studies have shown that IgGs bind differently to mouse and human FcRn. In this study we characterize a set of hu3S193 IgG1 variants with mutations in the FcRn binding site. A double mutation in the binding site is necessary to abrogate binding to murine FcRn, whereas a single mutation in the FcRn binding site is sufficient to no longer detect binding to human FcRn and create hu3S193 IgG1 variants with a half-life similar to previously studied hu3S193 F(ab')2 (t1/2ß, I253A, 12.23 h; H310A, 12.94; H435A, 12.57; F(ab')2, 12.6 h). Alanine substitutions in S254 in the CH2 domain and Y436 in the CH3 domain showed reduced binding in vitro to human FcRn and reduced elimination half-lives in huFcRn transgenic mice (t1/2ß, S254A, 37.43 h; Y436A, 39.53 h; wild-type, 83.15 h). These variants had minimal effect on half-life in BALB/c nu/nu mice (t1/2ß, S254A, 119.9 h; Y436A, 162.1 h; wild-type, 163.1 h). These results provide insight into the interaction of human Fc by human FcRn, and are important for antibody-based therapeutics with optimal pharmacokinetics for payload strategies used in the clinic.


Assuntos
Anticorpos Monoclonais/química , Antígenos de Histocompatibilidade Classe I/imunologia , Imunoglobulina G/química , Receptores Fc/química , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/farmacologia , Meia-Vida , Humanos , Imunoglobulina G/imunologia , Imunoglobulina G/farmacologia , Antígenos do Grupo Sanguíneo de Lewis/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Engenharia de Proteínas , Estabilidade Proteica , Receptores Fc/imunologia
17.
EJNMMI Res ; 6(1): 26, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26983636

RESUMO

BACKGROUND: The aim of the study was to explore Fc mutations of a humanised anti-Lewis-Y antibody (IgG1) hu3S193 as a strategy to improve therapeutic ratios for therapeutic payload delivery. METHODS: Four hu3S193 variants (I253A, H310A, H435A and I253A/H310A) were generated via site-directed mutagenesis and radiolabelled with diagnostic isotopes iodine-125 or indium-111. Biodistribution studies in Lewis-Y-positive tumour-bearing mice were used to calculate the dose in tumours and organs for therapeutic isotopes (iodine-131, yttrium-90 and lutetium-177). RESULTS: (111)In-labelled I253A and H435A showed similar slow kinetics (t 1/2ß, 63.2 and 62.2 h, respectively) and a maximum tumour uptake of 33.11 ± 4.05 and 33.69 ± 3.77 percentage injected dose per gramme (%ID/g), respectively. (111)In-labelled I253A/H310A cleared fastest (t 1/2ß, 9.1 h) with the lowest maximum tumour uptake (23.72 ± 0.85 %ID/g). The highest increase in tumour-to-blood area under the curve (AUC) ratio was observed with the metal-labelled mutants ((90)Y and (177)Lu). (177)Lu-CHX-A" DTPA-hu3S193 I253A/H310A (6:1) showed the highest tumour-to-blood AUC ratio compared to wild type (3:1) and other variants and doubling of calculated dose to tumour based on red marrow dose constraints. CONCLUSIONS: These results suggest that hu3S193 Fc can be engineered with improved therapeutic ratios for (90)Y- and (177)Lu-based therapy, with the best candidate being hu3S193 I253A/H310A for (177)Lu-based therapy.

18.
PLoS One ; 10(10): e0141729, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26513658

RESUMO

Malaria remains a significant global health burden. The development of an effective malaria vaccine remains as a major challenge with the potential to significantly reduce morbidity and mortality. While Plasmodium spp. have been shown to contain a large number of intrinsically disordered proteins (IDPs) or disordered protein regions, the relationship of protein structure to subcellular localisation and adaptive immune responses remains unclear. In this study, we employed several computational prediction algorithms to identify IDPs at the proteome level of six Plasmodium spp. and to investigate the potential impact of protein disorder on adaptive immunity against P. falciparum parasites. IDPs were shown to be particularly enriched within nuclear proteins, apical proteins, exported proteins and proteins localised to the parasitophorous vacuole. Furthermore, several leading vaccine candidates, and proteins with known roles in host-cell invasion, have extensive regions of disorder. Presentation of peptides by MHC molecules plays an important role in adaptive immune responses, and we show that IDP regions are predicted to contain relatively few MHC class I and II binding peptides owing to inherent differences in amino acid composition compared to structured domains. In contrast, linear B-cell epitopes were predicted to be enriched in IDPs. Tandem repeat regions and non-synonymous single nucleotide polymorphisms were found to be strongly associated with regions of disorder. In summary, immune responses against IDPs appear to have characteristics distinct from those against structured protein domains, with increased antibody recognition of linear epitopes but some constraints for MHC presentation and issues of polymorphisms. These findings have major implications for vaccine design, and understanding immunity to malaria.


Assuntos
Proteínas Intrinsicamente Desordenadas/imunologia , Plasmodium/imunologia , Proteoma , Proteômica , Proteínas de Protozoários/imunologia , Sequência de Aminoácidos , Aminoácidos , Biologia Computacional/métodos , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Antígenos de Histocompatibilidade Classe II/imunologia , Antígenos de Histocompatibilidade Classe II/metabolismo , Proteínas Intrinsicamente Desordenadas/química , Proteínas Intrinsicamente Desordenadas/genética , Peptídeos/química , Peptídeos/imunologia , Plasmodium falciparum/imunologia , Polimorfismo de Nucleotídeo Único , Ligação Proteica , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Sequências de Repetição em Tandem
19.
Methods Mol Biol ; 1331: 41-55, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26169734

RESUMO

Carbohydrate-protein recognition is vital to many processes in health and disease. In particular, elucidation of the structural basis of carbohydrate binding is important to the development of oligosaccharides and oligosaccharide mimetics as vaccines for infectious diseases and cancer. Computational structural techniques are valuable for the study of carbohydrate-protein recognition due to the challenges associated with experimental determination of carbohydrate-protein complexes. AutoMap is a computer program that we have developed to study protein-ligand recognition. AutoMap determines the interactions taking place in a set of highly ranked poses obtained from molecular docking and processes these to identify the protein residues most likely to be involved in interactions. In this protocol, we describe the use of AutoMap and illustrate its suitability for studying antibody recognition of the Lewis Y tetrasaccharide, which is a potential cancer vaccine antigen.


Assuntos
Anticorpos/química , Anticorpos/imunologia , Carboidratos/química , Carboidratos/imunologia , Humanos , Antígenos do Grupo Sanguíneo de Lewis/química , Antígenos do Grupo Sanguíneo de Lewis/imunologia , Ligantes , Modelos Moleculares , Oligossacarídeos/química , Oligossacarídeos/imunologia , Proteínas/química , Proteínas/imunologia
20.
Mol Immunol ; 67(2 Pt A): 1-3, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25990602

RESUMO

Therapeutic antibodies have come of age with major progress being made in cancer, autoimmunity and chronic inflammation, as well as a wide range of other human diseases. Antibody engineering is further driving development of novel antibody formats and genetically modified cell-based therapies that harness the power of the immune system to progress cures in otherwise intractable human diseases. Nevertheless, there are still significant challenges ahead for basic and applied research relating to therapeutic antibodies. This special issue of the journal provides reviews and opinions that relate to the discovery, design and deployment of antibodies as therapeutics.


Assuntos
Anticorpos/uso terapêutico , Imunoterapia/métodos , Terapia de Alvo Molecular/métodos , Neoplasias/terapia , Anticorpos/imunologia , Antineoplásicos/imunologia , Antineoplásicos/uso terapêutico , Desenho de Fármacos , Descoberta de Drogas , Humanos , Imunoterapia/tendências , Terapia de Alvo Molecular/tendências , Neoplasias/imunologia , Resultado do Tratamento
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