Differential Antibody Responses to Conserved HIV-1 Neutralizing Epitopes in the Context of Multivalent Scaffolds and Native-Like gp140 Trimers.

Science.gov (United States)

Morris, Charles D; Azadnia, Parisa; de Val, Natalia; Vora, Nemil; Honda, Andrew; Giang, Erick; Saye-Francisco, Karen; Cheng, Yushao; Lin, Xiaohe; Mann, Colin J; Tang, Jeffrey; Sok, Devin; Burton, Dennis R; Law, Mansun; Ward, Andrew B; He, Linling; Zhu, Jiang

2017-02-28

Broadly neutralizing antibodies (bNAbs) have provided valuable insights into the humoral immune response to HIV-1. While rationally designed epitope scaffolds and well-folded gp140 trimers have been proposed as vaccine antigens, a comparative understanding of their antibody responses has not yet been established. In this study, we probed antibody responses to the N332 supersite and the membrane-proximal external region (MPER) in the context of heterologous protein scaffolds and native-like gp140 trimers. Ferritin nanoparticles and fragment crystallizable (Fc) regions were utilized as multivalent carriers to display scaffold antigens with grafted N332 and MPER epitopes, respectively. Trimeric scaffolds were also identified to stabilize the MPER-containing BG505 gp140.681 trimer in a native-like conformation. Following structural and antigenic evaluation, a subset of scaffold and trimer antigens was selected for immunization in BALB/c mice. Serum binding revealed distinct patterns of antibody responses to these two bNAb targets presented in different structural contexts. For example, the N332 nanoparticles elicited glycan epitope-specific antibody responses that could also recognize the native trimer, while a scaffolded BG505 gp140.681 trimer generated a stronger and more rapid antibody response to the trimer apex than its parent gp140.664 trimer. Furthermore, next-generation sequencing (NGS) of mouse splenic B cells revealed expansion of antibody lineages with long heavy-chain complementarity-determining region 3 (HCDR3) loops upon activation by MPER scaffolds, in contrast to the steady repertoires primed by N332 nanoparticles and a soluble gp140.664 trimer. These findings will facilitate the future development of a coherent vaccination strategy that combines both epitope-focused and trimer-based approaches. IMPORTANCE Both epitope-focused and trimer-based strategies are currently being explored in HIV-1 vaccine development, which aims to elicit broadly neutralizing

Epitope Dampening Monotypic Measles Virus Hemagglutinin Glycoprotein Results in Resistance to Cocktail of Monoclonal Antibodies

Science.gov (United States)

Lech, Patrycja J.; Tobin, Gregory J.; Bushnell, Ruth; Gutschenritter, Emily; Pham, Linh D.; Nace, Rebecca; Verhoeyen, Els; Cosset, François-Loïc; Muller, Claude P.; Russell, Stephen J.; Nara, Peter L.

2013-01-01

The measles virus (MV) is serologically monotypic. Life-long immunity is conferred by a single attack of measles or following vaccination with the MV vaccine. This is contrary to viruses such as influenza, which readily develop resistance to the immune system and recur. A better understanding of factors that restrain MV to one serotype may allow us to predict if MV will remain monotypic in the future and influence the design of novel MV vaccines and therapeutics. MV hemagglutinin (H) glycoprotein, binds to cellular receptors and subsequently triggers the fusion (F) glycoprotein to fuse the virus into the cell. H is also the major target for neutralizing antibodies. To explore if MV remains monotypic due to a lack of plasticity of the H glycoprotein, we used the technology of Immune Dampening to generate viruses with rationally designed N-linked glycosylation sites and mutations in different epitopes and screened for viruses that escaped monoclonal antibodies (mAbs). We then combined rationally designed mutations with naturally selected mutations to generate a virus resistant to a cocktail of neutralizing mAbs targeting four different epitopes simultaneously. Two epitopes were protected by engineered N-linked glycosylations and two epitopes acquired escape mutations via two consecutive rounds of artificial selection in the presence of mAbs. Three of these epitopes were targeted by mAbs known to interfere with receptor binding. Results demonstrate that, within the epitopes analyzed, H can tolerate mutations in different residues and additional N-linked glycosylations to escape mAbs. Understanding the degree of change that H can tolerate is important as we follow its evolution in a host whose immunity is vaccine induced by genotype A strains instead of multiple genetically distinct wild-type MVs. PMID:23300970

A synthetic glycan microarray enables epitope mapping of plant cell wall glycan-directed antibodies

DEFF Research Database (Denmark)

Ruprecht, Colin; Bartetzko, Max P; Senf, Deborah

2017-01-01

In the last three decades, more than 200 monoclonal antibodies have been raised against most classes of plant cell wall polysaccharides by different laboratories world-wide. These antibodies are widely used to identify differences in plant cell wall components in mutants, organ and tissue types......, and developmental stages. Despite their importance and broad use, the precise binding epitope for only a few of these antibodies has been determined. Here, we use a plant glycan microarray equipped with 88 synthetic oligosaccharides to comprehensively map the epitopes of plant cell wall glycan-directed antibodies....... Our results reveal the binding epitopes for 78 arabinogalactan-, rhamnogalacturonan-, xylan-, and xyloglucan-directed antibodies. We demonstrate that, with knowledge of the exact epitopes recognized by individual antibodies, specific glycosyl hydrolases can be implemented into immunological cell wall...

Confirmation of antibodies against L-tryptophan-like epitope in ...

African Journals Online (AJOL)

Confirmation of antibodies against L-tryptophan-like epitope in human African trypanosomosis serological diagnostic. ... number of patients in Congo. A diagnostic test based on this synthetic epitope, especially in combination with other tests, might improve the HAT diagnostic test in field conditions. Key words: Tryptophan ...

Proof of principle for epitope-focused vaccine design

Science.gov (United States)

Correia, Bruno E.; Bates, John T.; Loomis, Rebecca J.; Baneyx, Gretchen; Carrico, Chris; Jardine, Joseph G.; Rupert, Peter; Correnti, Colin; Kalyuzhniy, Oleksandr; Vittal, Vinayak; Connell, Mary J.; Stevens, Eric; Schroeter, Alexandria; Chen, Man; MacPherson, Skye; Serra, Andreia M.; Adachi, Yumiko; Holmes, Margaret A.; Li, Yuxing; Klevit, Rachel E.; Graham, Barney S.; Wyatt, Richard T.; Baker, David; Strong, Roland K.; Crowe, James E.; Johnson, Philip R.; Schief, William R.

2014-03-01

Vaccines prevent infectious disease largely by inducing protective neutralizing antibodies against vulnerable epitopes. Several major pathogens have resisted traditional vaccine development, although vulnerable epitopes targeted by neutralizing antibodies have been identified for several such cases. Hence, new vaccine design methods to induce epitope-specific neutralizing antibodies are needed. Here we show, with a neutralization epitope from respiratory syncytial virus, that computational protein design can generate small, thermally and conformationally stable protein scaffolds that accurately mimic the viral epitope structure and induce potent neutralizing antibodies. These scaffolds represent promising leads for the research and development of a human respiratory syncytial virus vaccine needed to protect infants, young children and the elderly. More generally, the results provide proof of principle for epitope-focused and scaffold-based vaccine design, and encourage the evaluation and further development of these strategies for a variety of other vaccine targets, including antigenically highly variable pathogens such as human immunodeficiency virus and influenza.

A Linear Epitope in the N-Terminal Domain of CCR5 and Its Interaction with Antibody.

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Benny Chain

Full Text Available The CCR5 receptor plays a role in several key physiological and pathological processes and is an important therapeutic target. Inhibition of the CCR5 axis by passive or active immunisation offers one very selective strategy for intervention. In this study we define a new linear epitope within the extracellular domain of CCR5 recognised by two independently produced monoclonal antibodies. A short peptide encoding the linear epitope can induce antibodies which recognise the intact receptor when administered colinear with a tetanus toxoid helper T cell epitope. The monoclonal antibody RoAb 13 is shown to bind to both cells and peptide with moderate to high affinity (6x10^8 and 1.2x107 M-1 respectively, and binding to the peptide is enhanced by sulfation of tyrosines at positions 10 and 14. RoAb13, which has previously been shown to block HIV infection, also blocks migration of monocytes in response to CCR5 binding chemokines and to inflammatory macrophage conditioned medium. A Fab fragment of RoAb13 has been crystallised and a structure of the antibody is reported to 2.1 angstrom resolution.

Depigmented allergoids reveal new epitopes with capacity to induce IgG blocking antibodies.

Science.gov (United States)

López-Matas, M Angeles; Gallego, Mayte; Iraola, Víctor; Robinson, Douglas; Carnés, Jerónimo

2013-01-01

The synthesis of allergen-specific blocking IgGs that interact with IgE after allergen immunotherapy (SIT) has been related to clinical efficacy. The objectives were to investigate the epitope specificity of IgG-antibodies induced by depigmented-polymerized (Dpg-Pol) allergoids and unmodified allergen extracts, and examine IgE-blocking activity of induced IgG-antibodies. Rabbits were immunized with native and Dpg-Pol extracts of birch pollen, and serum samples were obtained. Recognition of linear IgG-epitopes of Bet v 1 and Bet v 2 and the capacity of these IgG-antibodies to block binding of human-IgE was determined. Serum from rabbits immunized with native extracts recognised 11 linear epitopes from Bet v 1, while that from Dpg-Pol-immunized animals recognised 8. For Bet v 2, 8 epitopes were recognized by IgG from native immunized animals, and 9 from Dpg-Pol immunized one. Dpg-Pol and native immunized serum did not always recognise the same epitopes, but specific-IgG from both could block human-IgE binding sites for native extract. Depigmented-polymerized birch extract stimulates the synthesis of specific IgG-antibodies which recognize common but also novel epitopes compared with native extracts. IgG-antibodies induced by Dpg-Pol effectively inhibit human-IgE binding to allergens which may be part of the mechanism of action of SIT.

Antibodies against linear epitopes on Goodpasture autoantigen in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis.

Science.gov (United States)

Jia, Xiao-Yu; Yu, Jun-Tao; Hu, Shui-Yi; Li, Jian-Nan; Wang, Miao; Wang, Chen; Chen, Min; Cui, Zhao; Zhao, Ming-Hui

2017-09-01

In a substantial number of patients with crescentic glomerulonephritis, both anti-glomerular basement membrane (GBM) antibodies and anti-neutrophil cytoplasmic antibodies (ANCA) are detected simultaneously. ANCA is presumed to be the initial event but the mechanism is unknown. In the present study, we investigated the antibodies against linear epitopes on Goodpasture autoantigen in sera from patients with ANCA-associated vasculitis, aiming to reveal the mechanisms of the coexistence of the two kinds of autoantibodies. Thirty-one patients with ANCA-associated vasculitis were enrolled in this study. Twenty-four overlapping linear peptides were synthesized across the whole sequence of Goodpasture autoantigen. Serum antibodies against linear peptides were detected by ELISA and their associations with clinical features were further analyzed. Twenty-five out of the thirty-one (80.6%) sera from patients with ANCA-associated vasculitis possessed antibodies against linear peptides on Goodpasture autoantigen. These antibodies could be detected in 50% of patients with normal renal function (Scr ≤ 133 μmol/L), 70% of patients with moderate renal dysfunction (133 μmol/L  600 μmol/L) (P = 0.032). The highest recognition frequencies were found for peptides P4 (51.6%), P14 (54.8%), and P24 (54.8%), which contained the sequences that constitute the conformational epitopes of E A (P4) and E B (P14) recognized by anti-GBM antibodies. The level of anti-P4 antibodies was positively correlated with the percentage of crescents in glomeruli (r = 0.764, P = 0.027). Patients with anti-P24 antibodies had a significantly higher prevalence of renal dysfunction on diagnosis (88.2 vs. 42.9%, P = 0.018). Antibodies against linear epitopes on Goodpasture autoantigen could be detected in sera of patients with ANCA-associated vasculitis, which might mediate the production of antibodies towards the conformational epitopes on Goodpasture autoantigen, namely, the anti-GBM antibodies.

Depigmented Allergoids Reveal New Epitopes with Capacity to Induce IgG Blocking Antibodies

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M. Angeles López-Matas

2013-01-01

Full Text Available Background. The synthesis of allergen-specific blocking IgGs that interact with IgE after allergen immunotherapy (SIT has been related to clinical efficacy. The objectives were to investigate the epitope specificity of IgG-antibodies induced by depigmented-polymerized (Dpg-Pol allergoids and unmodified allergen extracts, and examine IgE-blocking activity of induced IgG-antibodies. Methods. Rabbits were immunized with native and Dpg-Pol extracts of birch pollen, and serum samples were obtained. Recognition of linear IgG-epitopes of Bet v 1 and Bet v 2 and the capacity of these IgG-antibodies to block binding of human-IgE was determined. Results. Serum from rabbits immunized with native extracts recognised 11 linear epitopes from Bet v 1, while that from Dpg-Pol-immunized animals recognised 8. For Bet v 2, 8 epitopes were recognized by IgG from native immunized animals, and 9 from Dpg-Pol immunized one. Dpg-Pol and native immunized serum did not always recognise the same epitopes, but specific-IgG from both could block human-IgE binding sites for native extract. Conclusions. Depigmented-polymerized birch extract stimulates the synthesis of specific IgG-antibodies which recognize common but also novel epitopes compared with native extracts. IgG-antibodies induced by Dpg-Pol effectively inhibit human-IgE binding to allergens which may be part of the mechanism of action of SIT.

Structure of an antibody in complex with its mucin domain linear epitope that is protective against Ebola virus.

Science.gov (United States)

Olal, Daniel; Kuehne, Ana I; Bale, Shridhar; Halfmann, Peter; Hashiguchi, Takao; Fusco, Marnie L; Lee, Jeffrey E; King, Liam B; Kawaoka, Yoshihiro; Dye, John M; Saphire, Erica Ollmann

2012-03-01

Antibody 14G7 is protective against lethal Ebola virus challenge and recognizes a distinct linear epitope in the prominent mucin-like domain of the Ebola virus glycoprotein GP. The structure of 14G7 in complex with its linear peptide epitope has now been determined to 2.8 Å. The structure shows that this GP sequence forms a tandem β-hairpin structure that binds deeply into a cleft in the antibody-combining site. A key threonine at the apex of one turn is critical for antibody interaction and is conserved among all Ebola viruses. This work provides further insight into the mechanism of protection by antibodies that target the protruding, highly accessible mucin-like domain of Ebola virus and the structural framework for understanding and characterizing candidate immunotherapeutics.

Synthetic B-Cell Epitopes Eliciting Cross-Neutralizing Antibodies: Strategies for Future Dengue Vaccine.

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Babu Ramanathan

Full Text Available Dengue virus (DENV is a major public health threat worldwide. A key element in protection from dengue fever is the neutralising antibody response. Anti-dengue IgG purified from DENV-2 infected human sera showed reactivity against several peptides when evaluated by ELISA and epitope extraction techniques. A multi-step computational approach predicted six antigenic regions within the E protein of DENV-2 that concur with the 6 epitopes identified by the combined ELISA and epitope extraction approach. The selected peptides representing B-cell epitopes were attached to a known dengue T-helper epitope and evaluated for their vaccine potency. Immunization of mice revealed two novel synthetic vaccine constructs that elicited good humoral immune responses and produced cross-reactive neutralising antibodies against DENV-1, 2 and 3. The findings indicate new directions for epitope mapping and contribute towards the future development of multi-epitope based synthetic peptide vaccine.

A human monoclonal antibody derived from a vaccinated volunteer recognizes heterosubtypically a novel epitope on the hemagglutinin globular head of H1 and H9 influenza A viruses

International Nuclear Information System (INIS)

Boonsathorn, Naphatsawan; Panthong, Sumolrat; Koksunan, Sarawut; Chittaganpitch, Malinee; Phuygun, Siripaporn; Waicharoen, Sunthareeya; Prachasupap, Apichai; Sasaki, Tadahiro; Kubota-Koketsu, Ritsuko; Yasugi, Mayo; Ono, Ken-ichiro; Arai, Yasuha

2014-01-01

Highlights: • A human monoclonal antibody against influenza virus was produced from a volunteer. • The antibody was generated from the PBMCs of the volunteer using the fusion method. • The antibody neutralized heterosubtypically group 1 influenza A viruses (H1 and H9). • The antibody targeted a novel epitope in globular head region of the hemagglutinin. • Sequences of the identified epitope are highly conserved among H1 and H9 subtypes. - Abstract: Most neutralizing antibodies elicited during influenza virus infection or by vaccination have a narrow spectrum because they usually target variable epitopes in the globular head region of hemagglutinin (HA). In this study, we describe a human monoclonal antibody (HuMAb), 5D7, that was prepared from the peripheral blood lymphocytes of a vaccinated volunteer using the fusion method. The HuMAb heterosubtypically neutralizes group 1 influenza A viruses, including seasonal H1N1, 2009 pandemic H1N1 (H1N1pdm) and avian H9N2, with a strong hemagglutinin inhibition activity. Selection of an escape mutant showed that the HuMAb targets a novel conformational epitope that is located in the HA head region but is distinct from the receptor binding site. Furthermore, Phe114Ile substitution in the epitope made the HA unrecognizable by the HuMAb. Amino acid residues in the predicted epitope region are also highly conserved in the HAs of H1N1 and H9N2. The HuMAb reported here may be a potential candidate for the development of therapeutic/prophylactic antibodies against H1 and H9 influenza viruses

A human monoclonal antibody derived from a vaccinated volunteer recognizes heterosubtypically a novel epitope on the hemagglutinin globular head of H1 and H9 influenza A viruses

Energy Technology Data Exchange (ETDEWEB)

Boonsathorn, Naphatsawan; Panthong, Sumolrat [Medical Life Sciences Institute, Department of Medical Sciences, Ministry of Public Health, Muang, Nonthaburi (Thailand); Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo (Japan); Koksunan, Sarawut [Medical Life Sciences Institute, Department of Medical Sciences, Ministry of Public Health, Muang, Nonthaburi (Thailand); Chittaganpitch, Malinee; Phuygun, Siripaporn; Waicharoen, Sunthareeya [National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Muang, Nonthaburi (Thailand); Prachasupap, Apichai [Medical Life Sciences Institute, Department of Medical Sciences, Ministry of Public Health, Muang, Nonthaburi (Thailand); Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo (Japan); Sasaki, Tadahiro [Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo (Japan); Kubota-Koketsu, Ritsuko [Kanonji Institute, The Research Foundation for Microbial Diseases of Osaka University, Kanonji, Kagawa (Japan); Yasugi, Mayo [Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka (Japan); Ono, Ken-ichiro [Ina Laboratory, Medical and Biological Laboratories Corporation, Ltd., Ina, Nagano (Japan); Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Tokyo (Japan); Arai, Yasuha [Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); and others

2014-09-26

Highlights: • A human monoclonal antibody against influenza virus was produced from a volunteer. • The antibody was generated from the PBMCs of the volunteer using the fusion method. • The antibody neutralized heterosubtypically group 1 influenza A viruses (H1 and H9). • The antibody targeted a novel epitope in globular head region of the hemagglutinin. • Sequences of the identified epitope are highly conserved among H1 and H9 subtypes. - Abstract: Most neutralizing antibodies elicited during influenza virus infection or by vaccination have a narrow spectrum because they usually target variable epitopes in the globular head region of hemagglutinin (HA). In this study, we describe a human monoclonal antibody (HuMAb), 5D7, that was prepared from the peripheral blood lymphocytes of a vaccinated volunteer using the fusion method. The HuMAb heterosubtypically neutralizes group 1 influenza A viruses, including seasonal H1N1, 2009 pandemic H1N1 (H1N1pdm) and avian H9N2, with a strong hemagglutinin inhibition activity. Selection of an escape mutant showed that the HuMAb targets a novel conformational epitope that is located in the HA head region but is distinct from the receptor binding site. Furthermore, Phe114Ile substitution in the epitope made the HA unrecognizable by the HuMAb. Amino acid residues in the predicted epitope region are also highly conserved in the HAs of H1N1 and H9N2. The HuMAb reported here may be a potential candidate for the development of therapeutic/prophylactic antibodies against H1 and H9 influenza viruses.

Epitope Mapping of Monoclonal Antibody PMab-48 Against Dog Podoplanin.

Science.gov (United States)

Yamada, Shinji; Kaneko, Mika K; Itai, Shunsuke; Chang, Yao-Wen; Nakamura, Takuro; Yanaka, Miyuki; Ogasawara, Satoshi; Murata, Takeshi; Uchida, Hiroaki; Tahara, Hideaki; Harada, Hiroyuki; Kato, Yukinari

2018-04-02

Podoplanin (PDPN), a type I transmembrane sialoglycoprotein, is expressed on normal renal podocytes, pulmonary type I alveolar cells, and lymphatic endothelial cells. Increased expression of PDPN in cancers is associated with poor prognosis and hematogenous metastasis through interactions with C-type lectin-like receptor 2 (CLEC-2) on platelets. We previously reported a novel PMab-48 antibody, which is an anti-dog PDPN (dPDPN) monoclonal antibody (mAb) recognizing PDPN expressed in lymphatic endothelial cells. However, the binding epitope of PMab-48 is yet to be clarified. In this study, an enzyme-linked immunosorbent assay and flow cytometry were used to investigate epitopes of PMab-48. The results revealed that the critical epitope of PMab-48 comprises Asp29, Asp30, Ile31, Ile32, and Pro33 of dPDPN.

Measles Virus Hemagglutinin epitopes immunogenic in natural infection and vaccination are targeted by broad or genotype-specific neutralizing monoclonal antibodies.

Science.gov (United States)

Muñoz-Alía, Miguel Angel; Casasnovas, José M; Celma, María Luisa; Carabaña, Juan; Liton, Paloma B; Fernandez-Muñoz, Rafael

2017-05-15

Measles virus (MV) remains a leading cause of vaccine-preventable deaths in children. Protection against MV is associated with neutralizing antibodies that preferentially recognize the viral hemagglutinin (MV-H), and to a lesser extent, the fusion protein (MV-F). Although MV is serologically monotypic, 24 genotypes have been identified. Here we report three neutralization epitopes conserved in the more prevalent circulating MV genotypes, two located in the MV-H receptor binding site (RBS) (antigenic site III) and a third in MV-H/MV-F interphase (antigenic site Ia) which are essential for MV multiplication. In contrast, two MV-H neutralization epitopes, showed a genotype-specific neutralization escape due to a single amino acid change, that we mapped in the "noose" antigenic site, or an enhanced neutralization epitope (antigenic site IIa). The monoclonal antibody (mAb) neutralization potency correlated with its binding affinity and was mainly driven by kinetic dissociation rate (k off ). We developed an immunoassay for mAb binding to MV-H in its native hetero-oligomeric structure with MV-F on the surface of a MV productive steady-state persistently infected (p.i.) human cell lines, and a competitive-binding assay with serum from individuals with past infection by different MV genotypes. Binding assays revealed that a broad neutralization epitope, in RBS antigenic site, a genotype specific neutralization epitopes, in noose and IIa sites, were immunogenic in natural infection and vaccination and may elicit long-lasting humoral immunity that might contribute to explain MV immunogenic stability. These results support the design of improved measles vaccines, broad-spectrum prophylactic or therapeutic antibodies and MV-used in oncolytic therapies. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification and mapping of linear antibody epitopes in human serum albumin using high-density Peptide arrays.

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Lajla Bruntse Hansen

Full Text Available We have recently developed a high-density photolithographic, peptide array technology with a theoretical upper limit of 2 million different peptides per array of 2 cm(2. Here, we have used this to perform complete and exhaustive analyses of linear B cell epitopes of a medium sized protein target using human serum albumin (HSA as an example. All possible overlapping 15-mers from HSA were synthesized and probed with a commercially available polyclonal rabbit anti-HSA antibody preparation. To allow for identification of even the weakest epitopes and at the same time perform a detailed characterization of key residues involved in antibody binding, the array also included complete single substitution scans (i.e. including each of the 20 common amino acids at each position of each 15-mer peptide. As specificity controls, all possible 15-mer peptides from bovine serum albumin (BSA and from rabbit serum albumin (RSA were included as well. The resulting layout contained more than 200.000 peptide fields and could be synthesized in a single array on a microscope slide. More than 20 linear epitope candidates were identified and characterized at high resolution i.e. identifying which amino acids in which positions were needed, or not needed, for antibody interaction. As expected, moderate cross-reaction with some peptides in BSA was identified whereas no cross-reaction was observed with peptides from RSA. We conclude that high-density peptide microarrays are a very powerful methodology to identify and characterize linear antibody epitopes, and should advance detailed description of individual specificities at the single antibody level as well as serologic analysis at the proteome-wide level.

Identification and mapping of linear antibody epitopes in human serum albumin using high-density Peptide arrays.

Science.gov (United States)

Hansen, Lajla Bruntse; Buus, Soren; Schafer-Nielsen, Claus

2013-01-01

We have recently developed a high-density photolithographic, peptide array technology with a theoretical upper limit of 2 million different peptides per array of 2 cm(2). Here, we have used this to perform complete and exhaustive analyses of linear B cell epitopes of a medium sized protein target using human serum albumin (HSA) as an example. All possible overlapping 15-mers from HSA were synthesized and probed with a commercially available polyclonal rabbit anti-HSA antibody preparation. To allow for identification of even the weakest epitopes and at the same time perform a detailed characterization of key residues involved in antibody binding, the array also included complete single substitution scans (i.e. including each of the 20 common amino acids) at each position of each 15-mer peptide. As specificity controls, all possible 15-mer peptides from bovine serum albumin (BSA) and from rabbit serum albumin (RSA) were included as well. The resulting layout contained more than 200.000 peptide fields and could be synthesized in a single array on a microscope slide. More than 20 linear epitope candidates were identified and characterized at high resolution i.e. identifying which amino acids in which positions were needed, or not needed, for antibody interaction. As expected, moderate cross-reaction with some peptides in BSA was identified whereas no cross-reaction was observed with peptides from RSA. We conclude that high-density peptide microarrays are a very powerful methodology to identify and characterize linear antibody epitopes, and should advance detailed description of individual specificities at the single antibody level as well as serologic analysis at the proteome-wide level.

Identification of a new epitope in uPAR as a target for the cancer therapeutic monoclonal antibody ATN-658, a structural homolog of the uPAR binding integrin CD11b (αM.

Directory of Open Access Journals (Sweden)

Xiang Xu

Full Text Available The urokinase plasminogen activator receptor (uPAR plays a role in tumor progression and has been proposed as a target for the treatment of cancer. We recently described the development of a novel humanized monoclonal antibody that targets uPAR and has anti-tumor activity in multiple xenograft animal tumor models. This antibody, ATN-658, does not inhibit ligand binding (i.e. uPA and vitronectin to uPAR and its mechanism of action remains unclear. As a first step in understanding the anti-tumor activity of ATN-658, we set out to identify the epitope on uPAR to which ATN-658 binds. Guided by comparisons between primate and human uPAR, epitope mapping studies were performed using several orthogonal techniques. Systematic site directed and alanine scanning mutagenesis identified the region of aa 268-275 of uPAR as the epitope for ATN-658. No known function has previously been attributed to this epitope Structural insights into epitope recognition were obtained from structural studies of the Fab fragment of ATN-658 bound to uPAR. The structure shows that the ATN-658 binds to the DIII domain of uPAR, close to the C-terminus of the receptor, corroborating the epitope mapping results. Intriguingly, when bound to uPAR, the complementarity determining region (CDR regions of ATN-658 closely mimic the binding regions of the integrin CD11b (αM, a previously identified uPAR ligand thought to be involved in leukocyte rolling, migration and complement fixation with no known role in tumor progression of solid tumors. These studies reveal a new functional epitope on uPAR involved in tumor progression and demonstrate a previously unrecognized strategy for the therapeutic targeting of uPAR.

BepiPred-2.0: improving sequence-based B-cell epitope prediction using conformational epitopes

DEFF Research Database (Denmark)

Jespersen, Martin Closter; Peters, Bjoern; Nielsen, Morten

2017-01-01

Antibodies have become an indispensable tool for many biotechnological and clinical applications. They bind their molecular target (antigen) by recognizing a portion of its structure (epitope) in a highly specific manner. The ability to predict epitopes from antigen sequences alone is a complex t...

Docking of B-cell epitope antigen to specific hepatitis B antibody

Indian Academy of Sciences (India)

The interaction of pres1 region of hepatitis B virus B-cell epitope antigen with specific hepatitis B neutralizing monoclonal antibody was examined by docking study. We modelled the 3D complex structure of B-cell epitope antigen residues CTTPAQGNSMFPSCCCTKPTDGNCY by homology modelling and docked it with the ...

Analysis of potato virus Y coat protein epitopes recognized by three commercial monoclonal antibodies.

Science.gov (United States)

Tian, Yan-Ping; Hepojoki, Jussi; Ranki, Harri; Lankinen, Hilkka; Valkonen, Jari P T

2014-01-01

Potato virus Y (PVY, genus Potyvirus) causes substantial economic losses in solanaceous plants. Routine screening for PVY is an essential part of seed potato certification, and serological assays are often used. The commercial, commonly used monoclonal antibodies, MAb1128, MAb1129, and MAb1130, recognize the viral coat protein (CP) of PVY and distinguish PVYN strains from PVYO and PVYC strains, or detect all PVY strains, respectively. However, the minimal epitopes recognized by these antibodies have not been identified. SPOT peptide array was used to map the epitopes in CP recognized by MAb1128, MAb1129, and MAb1130. Then alanine replacement as well as N- and C-terminal deletion analysis of the identified peptide epitopes was done to determine critical amino acids for antibody recognition and the respective minimal epitopes. The epitopes of all antibodies were located within the 30 N-terminal-most residues. The minimal epitope of MAb1128 was 25NLNKEK30. Replacement of 25N or 27N with alanine weakened the recognition by MAb1128, and replacement of 26L, 29E, or 30K nearly precluded recognition. The minimal epitope for MAb1129 was 16RPEQGSIQSNP26 and the most critical residues for recognition were 22I and 23Q. The epitope of MAb1130 was defined by residues 5IDAGGS10. Mutation of residue 6D abrogated and mutation of 9G strongly reduced recognition of the peptide by MAb1130. Amino acid sequence alignment demonstrated that these epitopes are relatively conserved among PVY strains. Finally, recombinant CPs were produced to demonstrate that mutations in the variable positions of the epitope regions can affect detection with the MAbs. The epitope data acquired can be compared with data on PVY CP-encoding sequences produced by laboratories worldwide and utilized to monitor how widely the new variants of PVY can be detected with current seed potato certification schemes or during the inspection of imported seed potatoes as conducted with these MAbs.

Multiple epitopes in a dodecapeptide of myelin basic protein determined bymonoclonal antibodies

International Nuclear Information System (INIS)

Price, J.O.; Whitaker, J.N.; Vasu, R.I.; Metzger, D.W.

1986-01-01

Three custom synthesized myelin basic protein (MBP) peptides, bovine peptide 79-88, human peptide 80-89, and human peptide 82-91, were used to produce four murine monoclonal antibodies (MAb) that were selected on the basis of reaction in a solid phase radioimmunoassay (SRIA) with human MBP. The MAb were compared with respect to antigen specificity against intact MBP and 10 overlapping MBP peptides. One MAb recognized an epitope near the amino-terminus of bovine MBP peptide 79-88. A second MAb was directed towards an epitope that is more reactive in human MBP peptide 45-89 than in intact MBP, but is not recognized in any of the small MBP peptides examined. The third MAb detected an epitope near the middle of human MBP peptide 80-89, whereas the fourth MAb reacted with the carboxyl-terminal portion of human MBP peptide 82-91. Epitopes recognized in SRIA were sometimes not detected by the same MAb in a fluid phase double antibody radioimmunoassay. These results demonstrate the multiplicity of potential epitopes in a dodecapeptide of MBP and do not support the concept of a single, dominant epitope in the region of MBP peptide 80-89

Epitope Mapping of Monoclonal Antibody PMab-38 Against Dog Podoplanin.

Science.gov (United States)

Chang, Yao-Wen; Yamada, Shinji; Kaneko, Mika K; Kato, Yukinari

2017-12-01

Podoplanin (PDPN), a type I transmembrane sialoglycoprotein, is extensively expressed by normal lymphatic endothelial cells, renal podocytes, and pulmonary type I alveolar cells. Nevertheless, increased expression of PDPN in malignant tumors not only associates with poor prognosis but also facilitates hematogenous metastasis through interaction with C-type lectin-like receptor-2 presented on platelets, followed by PDPN-mediated platelet activation. We previously reported a novel PMab-38 antibody, an anti-dog PDPN (dPDPN) monoclonal antibody, which specifically recognizes PDPN in squamous cell carcinomas melanomas and cancer-associated fibroblasts in canine cancer tissues. However, the specific binding with the epitope of PMab-38 remains undefined. In this study, flow cytometry was utilized to investigate the epitope of PMab-38, which was determined using a series of deletion or point mutants of dPDPN. The results revealed that the critical epitope of PMab-38 is Tyr67 and Glu68 of dPDPN.

Usefulness of the nonself-self algorithm of HLA epitope immunogenicity in the specificity analysis of monospecific antibodies induced during pregnancy

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Rene J Duquesnoy

2015-05-01

Full Text Available Background HLAMatchmaker is a program to analyze the epitope specificities of HLA antibodies. It considers each HLA allele as a string of eplets. Intralocus and interlocus comparisons between donor and recipient alleles offer a structural assessment of compatibility and an analysis of allele panel reactivity patterns can generate information about epitope specificities of HLA antibodies. However, HLAMatchmaker cannot always generate conclusive interpretations of reactivity patterns of all monospecific antibodies which by definition recognize single epitopes. Hypothesis We have therefore developed a new antibody analysis approach that utilizes the nonself-self algorithm of HLA epitope immunogenicity. It is based in the concept that HLA antibodies originate from B-cells with immunoglobulin receptors to self HLA epitopes on one given allele and which can be activated by epitopes defined by a few nonself residue differences whereas the remainder of the structural epitope of the immunizing allele consists of self residues. Methods Three human monoclonal class I antibodies from HLA typed women sensitized during pregnancy were tested in Ig-binding assays with single alleles on a Luminex platformFindings Three new HLA epitopes were identified; they are defined by combinations of nonself and self residues for one allele of the antibody producer. Conclusion The nonself-self paradigm of HLA epitope immunogenicity offers a second approach to analyze HLA antibody specificities.

The POM monoclonals: a comprehensive set of antibodies to non-overlapping prion protein epitopes.

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Magdalini Polymenidou

Full Text Available PrP(Sc, a misfolded and aggregated form of the cellular prion protein PrP(C, is the only defined constituent of the transmissible agent causing prion diseases. Expression of PrP(C in the host organism is necessary for prion replication and for prion neurotoxicity. Understanding prion diseases necessitates detailed structural insights into PrP(C and PrP(Sc. Towards this goal, we have developed a comprehensive collection of monoclonal antibodies denoted POM1 to POM19 and directed against many different epitopes of mouse PrP(C. Three epitopes are located within the N-terminal octarepeat region, one is situated within the central unstructured region, and four epitopes are discontinuous within the globular C-proximal domain of PrP(C. Some of these antibodies recognize epitopes that are resilient to protease digestion in PrP(Sc. Other antibodies immunoprecipitate PrP(C, but not PrP(Sc. A third group was found to immunoprecipitate both PrP isoforms. Some of the latter antibodies could be blocked with epitope-mimicking peptides, and incubation with an excess of these peptides allowed for immunochromatography of PrP(C and PrP(Sc. Amino-proximal antibodies were found to react with repetitive PrP(C epitopes, thereby vastly increasing their avidity. We have also created functional single-chain miniantibodies from selected POMs, which retained the binding characteristics despite their low molecular mass. The POM collection, thus, represents a unique set of reagents allowing for studies with a variety of techniques, including western blotting, ELISA, immunoprecipitation, conformation-dependent immunoassays, and plasmon surface plasmon resonance-based assays.

Association analysis of anti-Epstein-Barr nuclear antigen-1 antibodies, anti-cyclic citrullinated peptide antibodies, the shared epitope and smoking status in Brazilian patients with rheumatoid arthritis

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Michel Alexandre Yazbek

2011-01-01

Full Text Available INTRODUCTION: Epstein-Barr virus exposure appears to be an environmental trigger for rheumatoid arthritis that interacts with other risk factors. Relationships among anti-cyclic citrullinated peptide antibodies, the shared epitope, and smoking status have been observed in patients with rheumatoid arthritis from different populations. OBJECTIVE: To perform an association analysis of anti-Epstein-Barr nuclear antigen-1 antibodies, anti-cyclic citrullinated peptide antibodies, the shared epitope, and smoking status in Brazilian patients with rheumatoid arthritis. METHODS: In a case-control study, 140 rheumatoid arthritis patients and 143 healthy volunteers who were matched for age, sex, and ethnicity were recruited. Anti-Epstein-Barr nuclear antigen-1 antibodies and anti-cyclic citrullinated peptide antibodies were examined using an enzyme-linked immunosorbent assay, and shared epitope alleles were identified by genotyping. Smoking information was collected from all subjects. A comparative analysis of anti-Epstein-Barr nuclear antigen-1 antibodies, anti-cyclic citrullinated peptide antibodies, the shared epitope, and smoking status was performed in the patient group. Logistic regression analysis models were used to analyze the risk of rheumatoid arthritis. RESULTS: Anti-Epstein-Barr nuclear antigen-1 antibodies were not associated with anti-cyclic citrullinated peptide antibodies, shared epitope alleles, or smoking status. Anti-cyclic citrullinated peptide antibody positivity was significantly higher in smoking patients with shared epitope alleles (OR = 3.82. In a multivariate logistic regression analysis using stepwise selection, only anti-cyclic citrullinated peptide antibodies were found to be independently associated with rheumatoid arthritis (OR = 247.9. CONCLUSION: Anti-Epstein-Barr nuclear antigen-1 antibodies did not increase the risk of rheumatoid arthritis and were not associated with the rheumatoid arthritis risk factors studied. Smoking

Viral O-GalNAc peptide epitopes

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Olofsson, Sigvard; Blixt, Klas Ola; Bergström, Tomas

2016-01-01

Viral envelope glycoproteins are major targets for antibodies that bind to and inactivate viral particles. The capacity of a viral vaccine to induce virus-neutralizing antibodies is often used as a marker for vaccine efficacy. Yet the number of known neutralization target epitopes is restricted o...

Comprehensive mapping of common immunodominant epitopes in the West Nile virus nonstructural protein 1 recognized by avian antibody responses.

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Encheng Sun

Full Text Available West Nile virus (WNV is a mosquito-borne flavivirus that primarily infects birds but occasionally infects humans and horses. Certain species of birds, including crows, house sparrows, geese, blue jays and ravens, are considered highly susceptible hosts to WNV. The nonstructural protein 1 (NS1 of WNV can elicit protective immune responses, including NS1-reactive antibodies, during infection of animals. The antigenicity of NS1 suggests that NS1-reactive antibodies could provide a basis for serological diagnostic reagents. To further define serological reagents for diagnostic use, the antigenic sites in NS1 that are targeted by host immune responses need to be identified and the potential diagnostic value of individual antigenic sites also needs to be defined. The present study describes comprehensive mapping of common immunodominant linear B-cell epitopes in the WNV NS1 using avian WNV NS1 antisera. We screened antisera from chickens, ducks and geese immunized with purified NS1 for reactivity against 35 partially overlapping peptides covering the entire WNV NS1. This study identified twelve, nine and six peptide epitopes recognized by chicken, duck and goose antibody responses, respectively. Three epitopes (NS1-3, 14 and 24 were recognized by antibodies elicited by immunization in all three avian species tested. We also found that NS1-3 and 24 were WNV-specific epitopes, whereas the NS1-14 epitope was conserved among the Japanese encephalitis virus (JEV serocomplex viruses based on the reactivity of avian WNV NS1 antisera against polypeptides derived from the NS1 sequences of viruses of the JEV serocomplex. Further analysis showed that the three common polypeptide epitopes were not recognized by antibodies in Avian Influenza Virus (AIV, Newcastle Disease Virus (NDV, Duck Plague Virus (DPV and Goose Parvovirus (GPV antisera. The knowledge and reagents generated in this study have potential applications in differential diagnostic approaches and

Extra-epitopic hepatitis C virus polymorphisms confer resistance to broadly neutralizing antibodies by modulating binding to scavenger receptor B1.

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El-Diwany, Ramy; Cohen, Valerie J; Mankowski, Madeleine C; Wasilewski, Lisa N; Brady, Jillian K; Snider, Anna E; Osburn, William O; Murrell, Ben; Ray, Stuart C; Bailey, Justin R

2017-02-01

Broadly-neutralizing monoclonal antibodies (bNAbs) may guide vaccine development for highly variable viruses including hepatitis C virus (HCV), since they target conserved viral epitopes that could serve as vaccine antigens. However, HCV resistance to bNAbs could reduce the efficacy of a vaccine. HC33.4 and AR4A are two of the most potent anti-HCV human bNAbs characterized to date, binding to highly conserved epitopes near the amino- and carboxy-terminus of HCV envelope (E2) protein, respectively. Given their distinct epitopes, it was surprising that these bNAbs showed similar neutralization profiles across a panel of natural HCV isolates, suggesting that some viral polymorphisms may confer resistance to both bNAbs. To investigate this resistance, we developed a large, diverse panel of natural HCV envelope variants and a novel computational method to identify bNAb resistance polymorphisms in envelope proteins (E1 and E2). By measuring neutralization of a panel of HCV pseudoparticles by 10 μg/mL of each bNAb, we identified E1E2 variants with resistance to one or both bNAbs, despite 100% conservation of the AR4A binding epitope across the panel. We discovered polymorphisms outside of either binding epitope that modulate resistance to both bNAbs by altering E2 binding to the HCV co-receptor, scavenger receptor B1 (SR-B1). This study is focused on a mode of neutralization escape not addressed by conventional analysis of epitope conservation, highlighting the contribution of extra-epitopic polymorphisms to bNAb resistance and presenting a novel mechanism by which HCV might persist even in the face of an antibody response targeting multiple conserved epitopes.

Monoclonal antibodies to molluskan hemocyanin from Concholepas concholepas demonstrate common and specific epitopes among subunits.

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Oliva, Harold; Moltedo, Bruno; De Ioannes, Pablo; Faunes, Fernando; De Ioannes, Alfredo E; Becker, María Inés

2002-10-01

We studied the reactivity of mouse monoclonal antibodies (MAbs) against the hemocyanin from the Chilean marine gastropod Concholepas concholepas (CCH). This protein has been successfully used as a carrier to produce antibodies to haptens and peptides. All MAbs (13) belonging to IgG subclass exhibit dissociation constants (K(d)) from 1 x 10(-7) M to 1 x 10(-9) M. MAbs were characterized by enzyme-linked immunosorbant assay (ELISA) using CCH treated with different procedures, including dissociation into CCH-A and CCH-B subunits, Western blot, enzymatic digestion, chemical deglycosylation, and thermal denaturation. MAbs were classified into three categories, according to subunit specificity by ELISA. The epitope distribution shows that CCH subunits display common epitopes (group I, 5 MAbs, 1H5, 2A8, 3A5, 3B3, and 3E3), as well as specific epitopes for CCH-A subunits (group II, 3 MAbs, 1B8, 4D8, and 8E5) and for CCH-B subunits (group III, 5 MAbs, 1A4, 1E4, 2H10, 3B7, and 7B4). The results can be summarized as follows: (1). six antibodies react with thermal denatured CCH, suggesting that they recognize linear epitopes, whereas seven recognize conformational epitopes; (2). oxidation of carbohydrate moieties does not affect the binding of the MAbs; (3). enzymatic digestion of CCH decreases the reactivity of all antibodies irrespective of the protease used (elastase or trypsin); (4). bringing together the above data, in addition to epitopic complementarity analysis, we identified 12 different epitopes on the CCH molecule recognized by these MAbs. The anti-CCH MAbs presented here can be useful tools to understand the subunit organization of the CCH and its complex structure, which can explain its immunogenic and immunostimulating properties in mammals.

Differential Antibody Responses to Conserved HIV-1 Neutralizing Epitopes in the Context of Multivalent Scaffolds and Native-Like gp140 Trimers

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Charles D. Morris

2017-02-01

Full Text Available Broadly neutralizing antibodies (bNAbs have provided valuable insights into the humoral immune response to HIV-1. While rationally designed epitope scaffolds and well-folded gp140 trimers have been proposed as vaccine antigens, a comparative understanding of their antibody responses has not yet been established. In this study, we probed antibody responses to the N332 supersite and the membrane-proximal external region (MPER in the context of heterologous protein scaffolds and native-like gp140 trimers. Ferritin nanoparticles and fragment crystallizable (Fc regions were utilized as multivalent carriers to display scaffold antigens with grafted N332 and MPER epitopes, respectively. Trimeric scaffolds were also identified to stabilize the MPER-containing BG505 gp140.681 trimer in a native-like conformation. Following structural and antigenic evaluation, a subset of scaffold and trimer antigens was selected for immunization in BALB/c mice. Serum binding revealed distinct patterns of antibody responses to these two bNAb targets presented in different structural contexts. For example, the N332 nanoparticles elicited glycan epitope-specific antibody responses that could also recognize the native trimer, while a scaffolded BG505 gp140.681 trimer generated a stronger and more rapid antibody response to the trimer apex than its parent gp140.664 trimer. Furthermore, next-generation sequencing (NGS of mouse splenic B cells revealed expansion of antibody lineages with long heavy-chain complementarity-determining region 3 (HCDR3 loops upon activation by MPER scaffolds, in contrast to the steady repertoires primed by N332 nanoparticles and a soluble gp140.664 trimer. These findings will facilitate the future development of a coherent vaccination strategy that combines both epitope-focused and trimer-based approaches.

'Multi-epitope-targeted' immune-specific therapy for a multiple sclerosis-like disease via engineered multi-epitope protein is superior to peptides.

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Nathali Kaushansky

Full Text Available Antigen-induced peripheral tolerance is potentially one of the most efficient and specific therapeutic approaches for autoimmune diseases. Although highly effective in animal models, antigen-based strategies have not yet been translated into practicable human therapy, and several clinical trials using a single antigen or peptidic-epitope in multiple sclerosis (MS yielded disappointing results. In these clinical trials, however, the apparent complexity and dynamics of the pathogenic autoimmunity associated with MS, which result from the multiplicity of potential target antigens and "epitope spread", have not been sufficiently considered. Thus, targeting pathogenic T-cells reactive against a single antigen/epitope is unlikely to be sufficient; to be effective, immunospecific therapy to MS should logically neutralize concomitantly T-cells reactive against as many major target antigens/epitopes as possible. We investigated such "multi-epitope-targeting" approach in murine experimental autoimmune encephalomyelitis (EAE associated with a single ("classical" or multiple ("complex" anti-myelin autoreactivities, using cocktail of different encephalitogenic peptides vis-a-vis artificial multi-epitope-protein (designated Y-MSPc encompassing rationally selected MS-relevant epitopes of five major myelin antigens, as "multi-epitope-targeting" agents. Y-MSPc was superior to peptide(s in concomitantly downregulating pathogenic T-cells reactive against multiple myelin antigens/epitopes, via inducing more effective, longer lasting peripheral regulatory mechanisms (cytokine shift, anergy, and Foxp3+ CTLA4+ regulatory T-cells. Y-MSPc was also consistently more effective than the disease-inducing single peptide or peptide cocktail, not only in suppressing the development of "classical" or "complex EAE" or ameliorating ongoing disease, but most importantly, in reversing chronic EAE. Overall, our data emphasize that a "multi-epitope-targeting" strategy is required for

Generation, characterization and epitope mapping of two neutralizing and protective human recombinant antibodies against influenza A H5N1 viruses.

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Lina Sun

Full Text Available BACKGROUND: The development of new therapeutic targets and strategies to control highly pathogenic avian influenza (HPAI H5N1 virus infection in humans is urgently needed. Broadly cross-neutralizing recombinant human antibodies obtained from the survivors of H5N1 avian influenza provide an important role in immunotherapy for human H5N1 virus infection and definition of the critical epitopes for vaccine development. METHODOLOGY/PRINCIPAL FINDINGS: We have characterized two recombinant baculovirus-expressed human antibodies (rhAbs, AVFluIgG01 and AVFluIgG03, generated by screening a Fab antibody phage library derived from a patient recovered from infection with a highly pathogenic avian influenza A H5N1 clade 2.3 virus. AVFluIgG01 cross-neutralized the most of clade 0, clade 1, and clade 2 viruses tested, in contrast, AVFluIgG03 only neutralized clade 2 viruses. Passive immunization of mice with either AVFluIgG01 or AVFluIgG03 antibody resulted in protection from a lethal H5N1 clade 2.3 virus infection. Furthermore, through epitope mapping, we identify two distinct epitopes on H5 HA molecule recognized by these rhAbs and demonstrate their potential to protect against a lethal H5N1 virus infection in a mouse model. CONCLUSIONS/SIGNIFICANCE: Importantly, localization of the epitopes recognized by these two neutralizing and protective antibodies has provided, for the first time, insight into the human antibody responses to H5N1 viruses which contribute to the H5 immunity in the recovered patient. These results highlight the potential of a rhAbs treatment strategy for human H5N1 virus infection and provide new insight for the development of effective H5N1 pandemic vaccines.

Epitope analysis of anti-myeloperoxidase antibodies in patients with ANCA-associated vasculitis.

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Shen-Ju Gou

Full Text Available OBJECTIVE: Increasing evidences have suggested the pathogenic role of anti-neutrophil cytoplasmic antibodies (ANCA directing myeloperoxidase (MPO in ANCA-associated vasculitis (AAV. The current study aimed to analyze the association between the linear epitopes of MPO-ANCA and clinicopathological features of patients with AAV. METHODS: Six recombinant linear fragments, covering the whole length amino acid sequence of a single chain of MPO, were produced from E.coli. Sera from 77 patients with AAV were collected at presentation. 13 out of the 77 patients had co-existence of serum anti-GBM antibodies. Ten patients also had sequential sera during follow up. The epitope specificities were detected by enzyme-linked immunosorbent assay using the recombinant fragments as solid phase ligands. RESULTS: Sera from 45 of the 77 (58.4% patients with AAV showed a positive reaction to one or more linear fragments of the MPO chain. The Birmingham Vasculitis Activity Scores and the sera creatinine were significantly higher in patients with positive binding to the light chain fragment than that in patients without the binding. The epitopes recognized by MPO-ANCA from patients with co-existence of serum anti-GBM antibodies were mainly located in the N-terminus of the heavy chain. In 5 out of the 6 patients, whose sera in relapse recognize linear fragments, the reactivity to linear fragments in relapse was similar to that of initial onset. CONCLUSION: The epitope specificities of MPO-ANCA were associated with disease activity and some clinicopathological features in patients with ANCA-associated vasculitis.

Indirect detection of an epitope-specific response to HIV-1 gp120 immunization in human subjects.

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Evgeny Shmelkov

Full Text Available A specific response of human serum neutralizing antibodies (nAb to a conformational epitope as a result of vaccination of human subjects with the surface envelope glycoprotein (gp120 of HIV-1 has not previously been documented. Here, we used computational analysis to assess the epitope-specific responses of human subjects, which were immunized with recombinant gp120 immunogens in the VAX003 and VAX004 clinical trials. Our computational methodology--a variation of sieve analysis--compares the occurrence of specific nAb targeted conformational 3D epitopes on viruses from infected individuals who received vaccination to the occurrence of matched epitopes in the viruses infecting placebo subjects. We specifically studied seven crystallographically defined nAb targeted conformational epitopes in the V3 loop, an immunogenic region of gp120. Of the six epitopes present in the immunogens and targeted by known monoclonal neutralizing antibodies, only the one targeted by the anti-V3 nAb 2219 exhibited a significant reduction in occurrence in vaccinated subjects compared to the placebo group. This difference occurred only in the VAX003 Thailand cohort. No difference was seen between vaccinated and placebo groups for the occurrence of an epitope that was not present in the immunogen. Thus, it can be theorized that a specific 2219-like human neutralizing antibody immune response to AIDSVAX immunization occurred in the VAX003 cohort, and that this response protected subjects from a narrow subset of HIV-1 viruses circulating in Thailand in the 1990s and bearing the conformational epitope targeted by the neutralizing antibody 2219.

In vivo tumor targeting and imaging with engineered trivalent antibody fragments containing collagen-derived sequences.

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Angel M Cuesta

Full Text Available There is an urgent need to develop new and effective agents for cancer targeting. In this work, a multivalent antibody is characterized in vivo in living animals. The antibody, termed "trimerbody", comprises a single-chain antibody (scFv fragment connected to the N-terminal trimerization subdomain of collagen XVIII NC1 by a flexible linker. As indicated by computer graphic modeling, the trimerbody has a tripod-shaped structure with three highly flexible scFv heads radially outward oriented. Trimerbodies are trimeric in solution and exhibited multivalent binding, which provides them with at least a 100-fold increase in functional affinity than the monovalent scFv. Our results also demonstrate the feasibility of producing functional bispecific trimerbodies, which concurrently bind two different ligands. A trimerbody specific for the carcinoembryonic antigen (CEA, a classic tumor-associated antigen, showed efficient tumor targeting after systemic administration in mice bearing CEA-positive tumors. Importantly, a trimerbody that recognizes an angiogenesis-associated laminin epitope, showed excellent tumor localization in several cancer types, including fibrosarcomas and carcinomas. These results illustrate the potential of this new antibody format for imaging and therapeutic applications, and suggest that some laminin epitopes might be universal targets for cancer targeting.

Epitope mapping of monoclonal antibodies directed to aminopeptidase A and their relevance for albuminuria in mice.

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Gerlofs-Nijland, Miriam E; Assmann, Karel J M; van Son, Jacco P H F; Dijkman, Henry B P M; te Loeke, Nathalie A J M; van der Zee, Ruurd; Wetzels, Jack F M; Groenen, Patricia J T A

2003-01-01

We have shown previously that injection of specific combinations of anti-aminopeptidase A monoclonal antibodies induces an acute massive albuminuria in mice. This albuminuria is neither dependent on systemic mediators of inflammation nor angiotensin II. In this study, we examined the contribution of two individual antibodies, the enzyme-inhibiting antibody ASD-37 and the non-enzyme-inhibiting antibody ASD-41, in the induction of albuminuria as well as the interactions between these two monoclonals. In addition, we have mapped the epitopes of both antibodies using in vitro coupled transcription/translation of specifically designed cDNA fragments followed by immunoprecipitation, and using peptide enzyme-linked immunosorbent assay in case of a continuous epitope. A single intravenous injection of 4 mg of either ASD-37 or ASD-41 did not induce albuminuria. This dose of ASD-37 did not completely inhibit enzyme activity. The combination of 4 mg ASD-37/41 (1:1 weight ratio) induced albuminuria and almost completely inhibited enzyme activity. Similar results were obtained with a combination of ASD-37/41 in a 1:39 or 39:1 weight ratio. Administration of 2 mg ASD-41 24 h before injection of 2 mg ASD-37 significantly enhanced albuminuria. The epitope of ASD-37 is located at the C-terminal end of aminopeptidase A, whereas the ASD-41 epitope is mapped near the enzyme active site. Our data suggest that ASD-41 modulates the binding of ASD-37 to its epitope and/or vice versa. As a consequence, ASD-37 and ASD-41 act synergistically, not only in inhibiting enzyme activity but also in inducing albuminuria. Copyright 2003 S. Karger AG, Basel

Peptide-Based Vaccinology: Experimental and Computational Approaches to Target Hypervariable Viruses through the Fine Characterization of Protective Epitopes Recognized by Monoclonal Antibodies and the Identification of T-Cell-Activating Peptides

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Matteo Castelli

2013-01-01

Full Text Available Defining immunogenic domains of viral proteins capable of eliciting a protective immune response is crucial in the development of novel epitope-based prophylactic strategies. This is particularly important for the selective targeting of conserved regions shared among hypervariable viruses. Studying postinfection and postimmunization sera, as well as cloning and characterization of monoclonal antibodies (mAbs, still represents the best approach to identify protective epitopes. In particular, a protective mAb directed against conserved regions can play a key role in immunogen design and in human therapy as well. Experimental approaches aiming to characterize protective mAb epitopes or to identify T-cell-activating peptides are often burdened by technical limitations and can require long time to be correctly addressed. Thus, in the last decade many epitope predictive algorithms have been developed. These algorithms are continually evolving, and their use to address the empirical research is widely increasing. Here, we review several strategies based on experimental techniques alone or addressed by in silico analysis that are frequently used to predict immunogens to be included in novel epitope-based vaccine approaches. We will list the main strategies aiming to design a new vaccine preparation conferring the protection of a neutralizing mAb combined with an effective cell-mediated response.

Conformational occlusion of blockade antibody epitopes, a novel mechanism of GII.4 human norovirus immune evasion

OpenAIRE

Lindesmith, Lisa C.; Mallory, Michael L.; Debbink, Kari; Donaldson, Eric F.; Brewer-Jensen, Paul D.; Swann, Excel W.; Sheahan, Timothy P.; Graham, Rachel L.; Beltramello, Martina; Corti, Davide; Lanzavecchia, Antonio; Baric, Ralph S.

2018-01-01

ABSTRACT Extensive antigenic diversity within the GII.4 genotype of human norovirus is a major driver of pandemic emergence and a significant obstacle to development of cross-protective immunity after natural infection and vaccination. However, human and mouse monoclonal antibody studies indicate that, although rare, antibodies to conserved GII.4 blockade epitopes are generated. The mechanisms by which these epitopes evade immune surveillance are uncertain. Here, we developed a new approach f...

Critical epitopes in the nucleocapsid protein of SFTS virus recognized by a panel of SFTS patients derived human monoclonal antibodies.

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Li Yu

Full Text Available BACKGROUND: SFTS virus (SFTSV is a newly discovered pathogen to cause severe fever with thrombocytopenia syndrome (SFTS in human. Successful control of SFTSV epidemic requires better understanding of the antigen target in humoral immune responses to the new bunyavirus infection. METHODOLOGY/PRINCIPAL FINDINGS: We have generated a combinatorial Fab antibody phage library from two SFTS patients recovered from SFTSV infection. To date, 94 unique human antibodies have been generated and characterized from over 1200 Fab antibody clones obtained by screening the library with SFTS purified virions. All those monoclonal antibodies (MAbs recognized the nucleocapsid (N protein of SFTSV while none of them were reactive to the viral glycoproteins Gn or Gc. Furthermore, over screening 1000 mouse monoclonal antibody clones derived from SFTSV virions immunization, 462 clones reacted with N protein, while only 16 clones were reactive to glycoprotein. Furthermore, epitope mapping of SFTSV N protein was performed through molecular simulation, site mutation and competitive ELISA, and we found that at least 4 distinct antigenic epitopes within N protein were recognized by those human and mouse MAbs, in particular mutation of Glu10 to Ala10 abolished or significantly reduced the binding activity of nearly most SFTS patients derived MAbs. CONCLUSIONS/SIGNIFICANCE: The large number of human recombinant MAbs derived from SFTS patients recognized the viral N protein indicated the important role of the N protein in humoral responses to SFTSV infection, and the critical epitopes we defined in this study provided molecular basis for detection and diagnosis of SFTSV infection.

Hepatitis C virus epitope exposure and neutralization by antibodies is affected by time and temperature

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Sabo, Michelle C; Luca, Vincent C; Ray, Stuart C

2012-01-01

A recent study with flaviviruses suggested that structural dynamics of the virion impact antibody neutralization via exposure of ostensibly cryptic epitopes. To determine whether this holds true for the distantly related hepatitis C virus (HCV), whose neutralizing epitopes may be obscured...... by a glycan shield, apolipoprotein interactions, and the hypervariable region on the E2 envelope protein, we assessed how time and temperature of pre-incubation altered monoclonal antibody (MAb) neutralization of HCV. Notably, several MAbs showed increased inhibitory activity when pre-binding was performed...

Built-in adjuvanticity of genetically and protein-engineered chimeric molecules for targeting of influenza A peptide epitopes.

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Kerekov, Nikola S; Ivanova, Iva I; Mihaylova, Nikolina M; Nikolova, Maria; Prechl, Jozsef; Tchorbanov, Andrey I

2014-10-01

Highly purified, subunit, or synthetic viral antigens are known to be weakly immunogenic and potentate only the antibody, rather than cell-mediated immune responses. An alternative approach for inducing protective immunity with small viral peptides would be the direct targeting of viral epitopes to the immunocompetent cells by DNA vaccines encoding antibody fragments specific to activating cell surface co-receptor molecules. Here, we are exploring as a new genetic vaccine, a DNA chimeric molecule encoding a T and B cell epitope-containing influenza A virus hemagglutinin peptide joined to sequences encoding a single-chain variable fragment antibody fragment specific for the costimulatory B cell complement receptors 1 and 2. This recombinant DNA molecule was inserted into eukaryotic expression vector and used as a naked DNA vaccine in WT and CR1/2 KO mice. The intramuscular administration of the DNA construct resulted in the in vivo expression of an immunogenic chimeric protein, which cross-links cell surface receptors on influenza-specific B cells. The DNA vaccination was followed by prime-boosting with the protein-engineered replica of the DNA construct, thus delivering an activation intracellular signal. Immunization with an expression vector containing the described construct and boosting with the protein chimera induced a strong anti-influenza cytotoxic response, modulation of cytokine profile, and a weak antibody response in Balb/c mice. The same immunization scheme did not result in generation of influenza-specific response in mice lacking the target receptor, underlining the molecular adjuvant effect of receptor targeting.

Computational identification of epitopes in the glycoproteins of novel bunyavirus (SFTS virus) recognized by a human monoclonal antibody (MAb 4-5)

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Zhang, Wenshuai; Zeng, Xiaoyan; Zhang, Li; Peng, Haiyan; Jiao, Yongjun; Zeng, Jun; Treutlein, Herbert R.

2013-06-01

In this work, we have developed a new approach to predict the epitopes of antigens that are recognized by a specific antibody. Our method is based on the "multiple copy simultaneous search" (MCSS) approach which identifies optimal locations of small chemical functional groups on the surfaces of the antibody, and identifying sequence patterns of peptides that can bind to the surface of the antibody. The identified sequence patterns are then used to search the amino-acid sequence of the antigen protein. The approach was validated by reproducing the binding epitope of HIV gp120 envelop glycoprotein for the human neutralizing antibody as revealed in the available crystal structure. Our method was then applied to predict the epitopes of two glycoproteins of a newly discovered bunyavirus recognized by an antibody named MAb 4-5. These predicted epitopes can be verified by experimental methods. We also discuss the involvement of different amino acids in the antigen-antibody recognition based on the distributions of MCSS minima of different functional groups.

Screening for epitope specificity directly on culture supernatants in the early phase of monoclonal antibody production by an ELISA with biotin-labeled antigen.

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Andersen, Ditte C; Jensen, Charlotte H; Gregersen, Annemette; Brandt, Jette; Kliem, Anette; Skjødt, Karsten; Koch, Claus; Teisner, Børge

2004-01-01

This report describes an assay for comparison of epitope specificity in groups of monoclonal antibodies against a given antigen. The only prerequisite is the biotin-labeled antigen. One of the monoclonal antibodies is captured onto a plastic surface via a rabbit anti-mouse Ig, and the other preincubated with biotinylated antigen. When the two antibodies react with the same epitope subsequent binding of the biotin-labeled antigen is abolished (inhibition). In the cases where no inhibition was observed, the two antibodies were considered to react with distinct, independent epitopes. The obvious advantages using this assay, are that it can be performed directly on culture supernatants in the early phase of monoclonal antibody production, and also works for antigens with repetitive epitopes. Moreover, the bonus effect, i.e., a signal in excess of the reference signal when sets of monoclonal antibodies with different epitope specificity are compared, gives a relative measure of affinity.

Generation and Characterization of Monoclonal Antibodies against a Cyclic Variant of Hepatitis C Virus E2 Epitope 412-422

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Sandomenico, Annamaria; Leonardi, Antonio; Berisio, Rita; Sanguigno, Luca; Focà, Giuseppina; Focà, Annalia; Ruggiero, Alessia; Doti, Nunzianna; Muscariello, Livio; Barone, Daniela; Farina, Claudio; Owsianka, Ania; Vitagliano, Luigi

2016-01-01

ABSTRACT The hepatitis C virus (HCV) E2 envelope glycoprotein is crucial for virus entry into hepatocytes. A conserved region of E2 encompassing amino acids 412 to 423 (epitope I) and containing Trp420, a residue critical for virus entry, is recognized by several broadly neutralizing antibodies. Peptides embodying this epitope I sequence adopt a β-hairpin conformation when bound to neutralizing monoclonal antibodies (MAbs) AP33 and HCV1. We therefore generated new mouse MAbs that were able to bind to a cyclic peptide containing E2 residues 412 to 422 (C-epitope I) but not to the linear counterpart. These MAbs bound to purified E2 with affinities of about 50 nM, but they were unable to neutralize virus infection. Structural analysis of the complex between C-epitope I and one of our MAbs (C2) showed that the Trp420 side chain is largely buried in the combining site and that the Asn417 side chain, which is glycosylated in E2 and solvent exposed in other complexes, is slightly buried upon C2 binding. Also, the orientation of the cyclic peptide in the antibody-combining site is rotated by 180° compared to the orientations of the other complexes. All these structural features, however, do not explain the lack of neutralization activity. This is instead ascribed to the high degree of selectivity of the new MAbs for the cyclic epitope and to their inability to interact with the epitope in more flexible and extended conformations, which recent data suggest play a role in the mechanisms of neutralization escape. IMPORTANCE Hepatitis C virus (HCV) remains a major health care burden, affecting almost 3% of the global population. The conserved epitope comprising residues 412 to 423 of the viral E2 glycoprotein is a valid vaccine candidate because antibodies recognizing this region exhibit potent neutralizing activity. This epitope adopts a β-hairpin conformation when bound to neutralizing MAbs. We explored the potential of cyclic peptides mimicking this structure to elicit

Tau Antibody Targeting Pathological Species Blocks Neuronal Uptake and Interneuron Propagation of Tau in Vitro.

Science.gov (United States)

Nobuhara, Chloe K; DeVos, Sarah L; Commins, Caitlin; Wegmann, Susanne; Moore, Benjamin D; Roe, Allyson D; Costantino, Isabel; Frosch, Matthew P; Pitstick, Rose; Carlson, George A; Hock, Christoph; Nitsch, Roger M; Montrasio, Fabio; Grimm, Jan; Cheung, Anne E; Dunah, Anthone W; Wittmann, Marion; Bussiere, Thierry; Weinreb, Paul H; Hyman, Bradley T; Takeda, Shuko

2017-06-01

The clinical progression of Alzheimer disease (AD) is associated with the accumulation of tau neurofibrillary tangles, which may spread throughout the cortex by interneuronal tau transfer. If so, targeting extracellular tau species may slow the spreading of tau pathology and possibly cognitive decline. To identify suitable target epitopes, we tested the effects of a panel of tau antibodies on neuronal uptake and aggregation in vitro. Immunodepletion was performed on brain extract from tau-transgenic mice and postmortem AD brain and added to a sensitive fluorescence resonance energy transfer-based tau uptake assay to assess blocking efficacy. The antibodies reduced tau uptake in an epitope-dependent manner: N-terminal (Tau13) and middomain (6C5 and HT7) antibodies successfully prevented uptake of tau species, whereas the distal C-terminal-specific antibody (Tau46) had little effect. Phosphorylation-dependent (40E8 and p396) and C-terminal half (4E4) tau antibodies also reduced tau uptake despite removing less total tau by immunodepletion, suggesting specific interactions with species involved in uptake. Among the seven antibodies evaluated, 6C5 most efficiently blocked uptake and subsequent aggregation. More important, 6C5 also blocked neuron-to-neuron spreading of tau in a unique three-chamber microfluidic device. Furthermore, 6C5 slowed down the progression of tau aggregation even after uptake had begun. Our results imply that not all antibodies/epitopes are equally robust in terms of blocking tau uptake of human AD-derived tau species. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Multiplexed screening of natural humoral immunity identifies antibodies at fine specificity for complex and dynamic viral targets.

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McCutcheon, Krista M; Gray, Julia; Chen, Natalie Y; Liu, Keyi; Park, Minha; Ellsworth, Stote; Tripp, Ralph A; Tompkins, S Mark; Johnson, Scott K; Samet, Shelly; Pereira, Lenore; Kauvar, Lawrence M

2014-01-01

Viral entry targets with therapeutic neutralizing potential are subject to multiple escape mechanisms, including antigenic drift, immune dominance of functionally irrelevant epitopes, and subtle variations in host cell mechanisms. A surprising finding of recent years is that potent neutralizing antibodies to viral epitopes independent of strain exist, but are poorly represented across the diverse human population. Identifying these antibodies and understanding the biology mediating the specific immune response is thus difficult. An effective strategy for meeting this challenge is to incorporate multiplexed antigen screening into a high throughput survey of the memory B cell repertoire from immune individuals. We used this approach to discover suites of cross-clade antibodies directed to conformational epitopes in the stalk region of the influenza A hemagglutinin (HA) protein and to select high-affinity anti-peptide antibodies to the glycoprotein B (gB) of human cytomegalovirus. In each case, our screens revealed a restricted VH and VL germline usage, including published and previously unidentified gene families. The in vivo evolution of paratope specificity with optimal neutralizing activity was understandable after correlating biological activities with kinetic binding and epitope recognition. Iterative feedback between antigen probe design based on structure and function information with high throughput multiplexed screening demonstrated a generally applicable strategy for efficient identification of safe, native, finely tuned antibodies with the potential for high genetic barriers to viral escape.

Epitope Sequences in Dengue Virus NS1 Protein Identified by Monoclonal Antibodies

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Leticia Barboza Rocha

2017-10-01

Full Text Available Dengue nonstructural protein 1 (NS1 is a multi-functional glycoprotein with essential functions both in viral replication and modulation of host innate immune responses. NS1 has been established as a good surrogate marker for infection. In the present study, we generated four anti-NS1 monoclonal antibodies against recombinant NS1 protein from dengue virus serotype 2 (DENV2, which were used to map three NS1 epitopes. The sequence 193AVHADMGYWIESALNDT209 was recognized by monoclonal antibodies 2H5 and 4H1BC, which also cross-reacted with Zika virus (ZIKV protein. On the other hand, the sequence 25VHTWTEQYKFQPES38 was recognized by mAb 4F6 that did not cross react with ZIKV. Lastly, a previously unidentified DENV2 NS1-specific epitope, represented by the sequence 127ELHNQTFLIDGPETAEC143, is described in the present study after reaction with mAb 4H2, which also did not cross react with ZIKV. The selection and characterization of the epitope, specificity of anti-NS1 mAbs, may contribute to the development of diagnostic tools able to differentiate DENV and ZIKV infections.

Elucidation of the TMab-6 Monoclonal Antibody Epitope Against Telomerase Reverse Transcriptase.

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Kaneko, Mika K; Yamada, Shinji; Itai, Shunsuke; Chang, Yao-Wen; Nakamura, Takuro; Yanaka, Miyuki; Harada, Hiroyuki; Suzuki, Hiroyoshi; Kato, Yukinari

2018-05-03

Telomerase reverse transcriptase (TERT) and mutations of the TERT promoter are significant in the pathogenesis of 1p/19q-codeleted oligodendrogliomas and isocitrate dehydrogenase gene wild-type glioblastomas, as well as melanomas and squamous cell carcinomas. We previously developed an antihuman TERT monoclonal antibody (mAb), TMab-6, which is applicable in immunohistochemistry for human tissues. However, the binding epitope of TMab-6 against TERT is yet to be elucidated. In this study, enzyme-linked immunosorbent assay and immunohistochemistry were utilized for investigating the epitope of TMab-6. The findings revealed that the critical epitope of TMab-6 is the TERT sequence PSTSRPPRPWD; Thr310 and Ser311 of TERT are especially significant amino acids for TMab-6 recognition.

Vaccine-induced antibodies to herpes simplex virus glycoprotein D epitopes involved in virus entry and cell-to-cell spread correlate with protection against genital disease in guinea pigs.

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Hook, Lauren M; Cairns, Tina M; Awasthi, Sita; Brooks, Benjamin D; Ditto, Noah T; Eisenberg, Roselyn J; Cohen, Gary H; Friedman, Harvey M

2018-05-01

Herpes simplex virus type 2 (HSV-2) glycoprotein D (gD2) subunit antigen is included in many preclinical candidate vaccines. The rationale for including gD2 is to produce antibodies that block crucial gD2 epitopes involved in virus entry and cell-to-cell spread. HSV-2 gD2 was the only antigen in the Herpevac Trial for Women that protected against HSV-1 genital infection but not HSV-2. In that trial, a correlation was detected between gD2 ELISA titers and protection against HSV-1, supporting the importance of antibodies. A possible explanation for the lack of protection against HSV-2 was that HSV-2 neutralization titers were low, four-fold lower than to HSV-1. Here, we evaluated neutralization titers and epitope-specific antibody responses to crucial gD2 epitopes involved in virus entry and cell-to-cell spread as correlates of immune protection against genital lesions in immunized guinea pigs. We detected a strong correlation between neutralizing antibodies and protection against genital disease. We used a high throughput biosensor competition assay to measure epitope-specific responses to seven crucial gD2 linear and conformational epitopes involved in virus entry and spread. Some animals produced antibodies to most crucial epitopes while others produced antibodies to few. The number of epitopes recognized by guinea pig immune serum correlated with protection against genital lesions. We confirmed the importance of antibodies to each crucial epitope using monoclonal antibody passive transfer that improved survival and reduced genital disease in mice after HSV-2 genital challenge. We re-evaluated our prior study of epitope-specific antibody responses in women in the Herpevac Trial. Humans produced antibodies that blocked significantly fewer crucial gD2 epitopes than guinea pigs, and antibody responses in humans to some linear epitopes were virtually absent. Neutralizing antibody titers and epitope-specific antibody responses are important immune parameters to

Flow shear stress differentially regulates endothelial uptake of nanocarriers targeted to distinct epitopes of PECAM-1.

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Han, Jingyan; Shuvaev, Vladimir V; Davies, Peter F; Eckmann, David M; Muro, Silvia; Muzykantov, Vladimir R

2015-07-28

Targeting nanocarriers (NC) to endothelial cell adhesion molecules including Platelet-Endothelial Cell Adhesion Molecule-1 (PECAM-1 or CD31) improves drug delivery and pharmacotherapy of inflammation, oxidative stress, thrombosis and ischemia in animal models. Recent studies unveiled that hydrodynamic conditions modulate endothelial endocytosis of NC targeted to PECAM-1, but the specificity and mechanism of effects of flow remain unknown. Here we studied the effect of flow on endocytosis by human endothelial cells of NC targeted by monoclonal antibodies Ab62 and Ab37 to distinct epitopes on the distal extracellular domain of PECAM. Flow in the range of 1-8dyn/cm(2), typical for venous vasculature, stimulated the uptake of spherical Ab/NC (~180nm diameter) carrying ~50 vs 200 Ab62 and Ab37 per NC, respectively. Effect of flow was inhibited by disruption of cholesterol-rich plasmalemma domains and deletion of PECAM-1 cytosolic tail. Flow stimulated endocytosis of Ab62/NC and Ab37/NC via eliciting distinct signaling pathways mediated by RhoA/ROCK and Src Family Kinases, respectively. Therefore, flow stimulates endothelial endocytosis of Ab/NC in a PECAM-1 epitope specific manner. Using ligands of binding to distinct epitopes on the same target molecule may enable fine-tuning of intracellular delivery based on the hemodynamic conditions in the vascular area of interest. Copyright © 2015 Elsevier B.V. All rights reserved.

Screening for epitope specificity directly on culture supernatants in the early phase of monoclonal antibody production by an ELISA with biotin-labeled antigen

DEFF Research Database (Denmark)

Andersen, Ditte C; Jensen, Charlotte H; Gregersen, Annemette

2004-01-01

This report describes an assay for comparison of epitope specificity in groups of monoclonal antibodies against a given antigen. The only prerequisite is the biotin-labeled antigen. One of the monoclonal antibodies is captured onto a plastic surface via a rabbit anti-mouse Ig, and the other...... preincubated with biotinylated antigen. When the two antibodies react with the same epitope subsequent binding of the biotin-labeled antigen is abolished (inhibition). In the cases where no inhibition was observed, the two antibodies were considered to react with distinct, independent epitopes. The obvious...

Substantial gaps in knowledge of Bordetella pertussis antibody and T cell epitopes relevant for natural immunity and vaccine efficacy

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Vaughan, Kerrie; Seymour, Emily; Peters, Bjoern; Sette, Alessandro

2016-01-01

The recent increase in whooping cough in vaccinated populations has been attributed to waning immunity associated with the acellular vaccine. The Immune Epitope Database (IEDB) is a repository of immune epitope data from the published literature and includes T cell and antibody epitopes for human pathogens. The IEDB conducted a review of the epitope literature, which revealed 300 Bordetella pertussis-related epitopes from 39 references. Epitope data are currently available for six virulence factors of B. pertussis: pertussis toxin, pertactin, fimbrial 2, fimbrial 3, adenylate cyclase and filamentous hemagglutinin. The majority of epitopes were defined for antibody reactivity; fewer T cell determinants were reported. Analysis of available protective correlates data revealed a number of candidate epitopes; however few are defined in humans and few have been shown to be protective. Moreover, there are a limited number of studies defining epitopes from natural infection versus whole cell or acellular/subunit vaccines. The relationship between epitope location and structural features, as well as antigenic drift (SNP analysis) was also investigated. We conclude that the cumulative data is yet insufficient to address many fundamental questions related to vaccine failure and this underscores the need for further investigation of B. pertussis immunity at the molecular level. PMID:24530743

Conserved B-cell epitopes among human bocavirus species indicate potential diagnostic targets.

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Zhuo Zhou

Full Text Available BACKGROUND: Human bocavirus species 1-4 (HBoV1-4 have been associated with respiratory and enteric infections in children. However, the immunological mechanisms in response to HBoV infections are not fully understood. Though previous studies have shown cross-reactivities between HBoV species, the epitopes responsible for this phenomenon remain unknown. In this study, we used genomic and immunologic approaches to identify the reactive epitopes conserved across multiple HBoV species and explored their potential as the basis of a novel diagnostic test for HBoVs. METHODOLOGY/PRINCIPAL FINDINGS: We generated HBoV1-3 VP2 gene fragment phage display libraries (GFPDLs and used these libraries to analyze mouse antisera against VP2 protein of HBoV1, 2, and 3, and human sera positive for HBoVs. Using this approach, we mapped four epitope clusters of HBoVs and identified two immunodominant peptides--P1 (¹MSDTDIQDQQPDTVDAPQNT²⁰, and P2 (¹⁶²EHAYPNASHPWDEDVMPDL¹⁸⁰--that are conserved among HBoV1-4. To confirm epitope immunogenicity, we immunized mice with the immunodominant P1 and P2 peptides identified in our screen and found that they elicited high titer antibodies in mice. These two antibodies could only recognize the VP2 of HBoV 1-4 in Western blot assays, rather than those of the two other parvoviruses human parvovirus B19 and human parvovirus 4 (PARV4. Based on our findings, we evaluated epitope-based peptide-IgM ELISAs as potential diagnostic tools for HBoVs IgM antibodies. We found that the P1+P2-IgM ELISA showed a higher sensitivity and specificity in HBoVs IgM detection than the assays using a single peptide. CONCLUSIONS/SIGNIFICANCE: The identification of the conserved B-cell epitopes among human bocavirus species contributes to our understanding of immunological cross-reactivities of HBoVs, and provides important insights for the development of HBoV diagnostic tools.

Epitope Mapping of Monoclonal Antibody PMab-52 Against Cat Podoplanin.

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Chang, Yao-Wen; Kaneko, Mika K; Yamada, Shinji; Kato, Yukinari

2018-02-02

The mucin-type membrane glycoprotein podoplanin (PDPN) is frequently overexpressed in numerous malignant cancers, including squamous cell carcinoma, germinal neoplasia, mesothelioma, lung cancer, oral cancer, and brain tumor. PDPN expression is strongly associated with cancer progression and poor prognosis. Furthermore, PDPN binds to C-type lectin-like receptor 2 (CLEC-2) on platelets, followed by PDPN-mediated platelet aggregation to facilitate tumor metastasis. We have previously reported a novel anti-cat PDPN (cPDPN) monoclonal antibody (mAb), PMab-52, which specifically detects cPDPN using flow cytometry analysis and successfully identifies cPDPN in feline squamous cell carcinomas. However, the specific binding epitope of cPDPN for PMab-52 remains unelucidated. In this study, a series of deletion or point mutants of cPDPN were utilized for investigating the binding epitopes of PMab-52 using flow cytometry and Western blotting. The findings of this study revealed that the critical epitopes of platelet aggregation-stimulating domain 4 (PLAG4) of cPDPN are responsible for the binding of PMab-52 to cPDPN.

Design and characterization of epitope-scaffold immunogens that present the motavizumab epitope from respiratory syncytial virus.

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McLellan, Jason S; Correia, Bruno E; Chen, Man; Yang, Yongping; Graham, Barney S; Schief, William R; Kwong, Peter D

2011-06-24

Respiratory syncytial virus (RSV) is a major cause of respiratory tract infections in infants, but an effective vaccine has not yet been developed. An ideal vaccine would elicit protective antibodies while avoiding virus-specific T-cell responses, which have been implicated in vaccine-enhanced disease with previous RSV vaccines. We propose that heterologous proteins designed to present RSV-neutralizing antibody epitopes and to elicit cognate antibodies have the potential to fulfill these vaccine requirements, as they can be fashioned to be free of viral T-cell epitopes. Here we present the design and characterization of three epitope-scaffolds that present the epitope of motavizumab, a potent neutralizing antibody that binds to a helix-loop-helix motif in the RSV fusion glycoprotein. Two of the epitope-scaffolds could be purified, and one epitope-scaffold based on a Staphylococcus aureus protein A domain bound motavizumab with kinetic and thermodynamic properties consistent with the free epitope-scaffold being stabilized in a conformation that closely resembled the motavizumab-bound state. This epitope-scaffold was well folded as assessed by circular dichroism and isothermal titration calorimetry, and its crystal structure (determined in complex with motavizumab to 1.9 Å resolution) was similar to the computationally designed model, with all hydrogen-bond interactions critical for binding to motavizumab preserved. Immunization of mice with this epitope-scaffold failed to elicit neutralizing antibodies but did elicit sera with F binding activity. The elicitation of F binding antibodies suggests that some of the design criteria for eliciting protective antibodies without virus-specific T-cell responses are being met, but additional optimization of these novel immunogens is required. Published by Elsevier Ltd.

Production, Characterization and Use of Monoclonal Antibodies Recognizing IgY Epitopes Shared by Chicken, Turkey, Pheasant, Peafowl and Sparrow

OpenAIRE

Narat, Mojca; Biček, Ajda; Vadnjal, Robert; Benčina, Dušan

2004-01-01

Chicken antibodies are not only a part of immune defense but are more and more popular commercial products in form of chicken polyclonal, monoclonal or recombinant antibodies. We produced and characterized mouse monoclonal antibodies (mAbs) that recognize epitopes located on heavy or light chain of chicken immunoglobulin Y (chIgY) shared also by some other Phasianidae birds. The use of mAbs 1F5 and 2F10 that recognize heavy chain on chIgY common epitopes was demonstrated on immunoglobulins of...

Immunodominant IgM and IgG Epitopes Recognized by Antibodies Induced in Enterovirus A71-Associated Hand, Foot and Mouth Disease Patients.

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Kam Leng Aw-Yong

Full Text Available Enterovirus A71 (EV-A71 is one of the main causative agents of hand, foot and mouth disease (HFMD. Unlike other enteroviruses that cause HFMD, EV-A71 is more frequently associated with severe neurological complications and fatality. To date, no effective licensed antivirals are available to combat EV-A71 infection. Little is known about the immunogenicity of viral non-structural proteins in humans. Previous studies have mainly focused on characterization of epitopes of EV-A71 structural proteins by using immunized animal antisera. In this study, we have characterized human antibody responses against the structural and non-structural proteins of EV-A71. Each viral protein was cloned and expressed in either bacterial or mammalian systems, and tested with antisera by western blot. Results revealed that all structural proteins (VP1-4, and non-structural proteins 2A, 3C and 3D were targets of EV-A71 IgM, whereas EV-A71 IgG recognized all the structural and non-structural proteins. Sixty three synthetic peptides predicted to be immunogenic in silico were synthesized and used for the characterization of EV-A71 linear B-cell epitopes. In total, we identified 22 IgM and four IgG dominant epitopes. Synthetic peptide PEP27, corresponding to residues 142-156 of VP1, was identified as the EV-A71 IgM-specific immunodominant epitope. PEP23, mapped to VP1 41-55, was recognized as the EV-A71 IgG cross-reactive immunodominant epitope. The structural protein VP1 is the major immunodominant site targeted by anti-EV-A71 IgM and IgG antibodies, but epitopes against non-structural proteins were also detected. These data provide new understanding of the immune response to EV-A71 infection, which benefits the development of diagnostic tools, potential therapeutics and subunit vaccine candidates.

Deciphering allogeneic antibody response against native and denatured HLA epitopes in organ transplantation.

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Visentin, Jonathan; Guidicelli, Gwendaline; Moreau, Jean-François; Lee, Jar-How; Taupin, Jean-Luc

2015-07-01

Anti-HLA donor-specific antibodies are deleterious for organ transplant survival. Class I HLA donor-specific antibodies are identified by using the Luminex single antigen beads (LSAB) assay, which also detects anti-denatured HLA antibodies (anti-dHLAs). Anti-dHLAs are thought to be unable to recognize native HLA (nHLA) on the cell surface and therefore to be clinically irrelevant. Acid denaturation of nHLA on LSAB allows anti-dHLAs to be discriminated from anti-nHLAs. We previously defined a threshold for the ratio between mean fluorescence intensity against acid-treated (D for denaturation) and nontreated (N) LSAB, D ≥ 1.2 N identifying the anti-dHLAs. However, some anti-dHLAs remained able to bind nHLA on lymphocytes in flow cytometry crossmatches, and some anti-nHLAs conserved significant reactivity toward acid-treated LSAB. After depleting serum anti-nHLA reactivity with HLA-typed cells, we analyzed the residual LSAB reactivity toward nontreated and acid-treated LSABs, and then evaluated the ability of antibodies to recognize nHLA alleles individually. We observed that sera can contain mixtures of anti-nHLAs and anti-dHLAs, or anti-nHLAs recognizing acid-resistant epitopes, all possibly targeting the same allele(s). Therefore, the anti-HLA antibody response can be highly complex and subtle, as is the accurate identification of pathogenic anti-HLA antibodies in human serum. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterisation of the epitope for a herpes simplex virus glycoprotein B-specific monoclonal antibody with high protective capacity.

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Däumer, Martin P; Schneider, Beate; Giesen, Doris M; Aziz, Sheriff; Kaiser, Rolf; Kupfer, Bernd; Schneweis, Karl E; Schneider-Mergener, Jens; Reineke, Ulrich; Matz, Bertfried; Eis-Hübinger, Anna M

2011-05-01

Monoclonal antibody (MAb) 2c, specific for glycoprotein B of herpes simplex virus (HSV), had been shown to mediate clearance of infection from the mucous membranes of mice, thereby completely inhibiting mucocutaneous inflammation and lethality, even in mice depleted of both CD4(+) and CD8(+) cells. Additionally, ganglionic infection was highly restricted. In vitro, MAb 2c exhibits a potent complement-independent neutralising activity against HSV type 1 and 2, completely inhibits the viral cell-to-cell spread as well as the syncytium formation induced by syncytial HSV strains (Eis-Hübinger et al. in Intervirology 32:351-360, 1991; Eis-Hübinger et al. in J Gen Virol 74:379-385, 1993). Here, we describe the mapping of the epitope for MAb 2c. The antibody was found to recognise a discontinuous epitope comprised of the HSV type 1 glycoprotein B residues 299 to 305 and one or more additional discontinuous regions that can be mimicked by the sequence FEDF. Identification of the epitope was confirmed by loss of antibody binding to mutated glycoprotein B with replacement of the epitopic key residues, expressed in COS-1 cells. Similarly, MAb 2c was not able to neutralise HSV mutants with altered key residues, and MAb 2c was ineffective in mice inoculated with such mutants. Interestingly, identification and fine-mapping of the discontinuous epitope was not achieved by binding studies with truncated glycoprotein B variants expressed in COS cells but by peptide scanning with synthetic overlapping peptides and peptide key motif analysis. Reactivity of MAb 2c was immensely increased towards a peptide composed of the glycoprotein B residues 299 to 305, a glycine linker, and a C-terminal FEDF motif. If it could be demonstrated that antibodies of the specificity and bioactivity of MAb 2c can be induced by the epitope or a peptide mimicking the epitope, strategies for active immunisation might be conceivable.

Targeting of human glioma xenografts in vivo utilizing radiolabeled antibodies

International Nuclear Information System (INIS)

Williams, J.A.; Wessels, B.W.; Wharam, M.D.; Order, S.E.; Wanek, P.M.; Poggenburg, J.K.; Klein, J.L.

1990-01-01

Radiolabeled antibodies provide a potential basis for selective radiotherapy of human gliomas. We have measured tumor targeting by radiolabeled monoclonal and polyclonal antibodies directed against neuroectodermal and tumor-associated antigens in nude mice bearing human glioma xenografts. Monoclonal P96.5, a mouse IgG2a immunoglobulin, defines an epitope of a human melanoma cell surface protein, and specifically binds the U-251 human glioma as measured by immunoperoxidase histochemistry. 111In-radiolabeled P96.5 specifically targets the U-251 human glioma xenograft and yields 87.0 microCuries (microCi) of tumor activity per gram per 100 microCi injected activity compared to 4.5 microCi following administration of radiolabeled irrelevant monoclonal antibody. Calculations of targeting ratios demonstrate deposited dose to be 11.6 times greater with radiolabeled P96.5 administration compared to irrelevant monoclonal antibody. The proportion of tumor dose found in normal organs is less than 10%, further supporting specific targeting of the human glioma xenograft by this antibody. Monoclonal antibody ZME018, which defines a second melanoma-associated antigen, and polyclonal rabbit antiferritin, which defines a tumor-associated antigen, demonstrate positive immunoperoxidase staining of the tumor, but comparatively decreased targeting. When compared to the 111In-radiolabeled antibody, 90Y-radiolabeled P96.5 demonstrates comparable tumor targeting and percentages of tumor dose found in normal organs. To test the therapeutic potential of 90Y-radiolabeled P96.5, tumors and normal sites were implanted with miniature thermoluminescent dosimeters (TLD). Seven days following administration of 100 microCi 90Y-radiolabeled P96.5, average absorbed doses of 3770, 980, 353, and 274 cGy were observed in tumor, liver, contralateral control site, and total body, respectively

Designing Probes for Immunodiagnostics: Structural Insights into an Epitope Targeting Burkholderia Infections.

Science.gov (United States)

Capelli, Riccardo; Matterazzo, Elena; Amabili, Marco; Peri, Claudio; Gori, Alessandro; Gagni, Paola; Chiari, Marcella; Lertmemongkolchai, Ganjana; Cretich, Marina; Bolognesi, Martino; Colombo, Giorgio; Gourlay, Louise J

2017-10-13

Structure-based epitope prediction drives the design of diagnostic peptidic probes to reveal specific antibodies elicited in response to infections. We previously identified a highly immunoreactive epitope from the peptidoglycan-associated lipoprotein (Pal) antigen from Burkholderia pseudomallei, which could also diagnose Burkholderia cepacia infections. Here, considering the high phylogenetic conservation within Burkholderia species, we ask whether cross-reactivity can be reciprocally displayed by the synthetic epitope from B. cenocepacia. We perform comparative analyses of the conformational preferences and diagnostic performances of the corresponding epitopes from the two Burkholderia species when presented in the context of the full-length proteins or as isolated peptides. The effects of conformation on the diagnostic potential and cross-reactivity of Pal peptide epitopes are rationalized on the basis of the 1.8 Å crystal structure of B. cenocepacia Pal and through computational analyses. Our results are discussed in the context of designing new diagnostic molecules for the early detection of infectious diseases.

Development of a sensitive and specific epitope-blocking ELISA for universal detection of antibodies to human enterovirus 71 strains.

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Fang He

Full Text Available BACKGROUND: Human Enterovirus 71 (EV71 is a common cause of hand, foot and mouth disease (HFMD in young children. It is often associated with severe neurological diseases and mortalities in recent outbreaks across the Asia Pacific region. Currently, there is no efficient universal antibody test available to detect EV71 infections. METHODOLOGY/PRINCIPAL FINDING: In the present study, an epitope-blocking ELISA was developed to detect specific antibodies to human EV71 viruses in human or animal sera. The assay relies on a novel monoclonal antibody (Mab 1C6 that specifically binds to capsid proteins in whole EV71 viruses without any cross reaction to any EV71 capsid protein expressed alone. The sensitivity and specificity of the epitope-blocking ELISA for EV71 was evaluated and compared to microneutralization using immunized animal sera to multiple virus genotypes of EV71 and coxsackieviruses. Further, 200 serum sample from human individuals who were potentially infected with EV71 viruses were tested in both the blocking ELISA and microneutralization. Results indicated that antibodies to EV71 were readily detected in immunized animals or human sera by the epitope blocking ELISA whereas specimens with antibodies to other enteroviruses yielded negative results. This assay is not only simpler to perform but also shows higher sensitivity and specificity as compared to microneutralization. CONCLUSION: The epitope-blocking ELISA based on a unique Mab 1C6 provided highly sensitive and 100% specific detection of antibodies to human EV71 viruses in human sera.

Prediction of Antibody Epitopes

DEFF Research Database (Denmark)

Nielsen, Morten; Marcatili, Paolo

2015-01-01

Antibodies recognize their cognate antigens in a precise and effective way. In order to do so, they target regions of the antigenic molecules that have specific features such as large exposed areas, presence of charged or polar atoms, specific secondary structure elements, and lack of similarity...... to self-proteins. Given the sequence or the structure of a protein of interest, several methods exploit such features to predict the residues that are more likely to be recognized by an immunoglobulin.Here, we present two methods (BepiPred and DiscoTope) to predict linear and discontinuous antibody...

Ovarian carcinoma glyco-antigen targeted by human IgM antibody.

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Yi Chen

Full Text Available Epithelial Ovarian Cancer (EOC cells expression of a novel carbohydrate antigen was defined using a human VH4-34 encoded IgM monoclonal antibody (mAb216. MAb216 binds to a poly N-acetyllactosamine epitope expressed on B cells and kills normal and malignant B cells in vitro and in vivo. EOC patient ascites and EOC cell lines were used to study the anti tumor effect of mAb216. Various assays were used to characterize the epitope and demonstrate antibody-mediated binding and cytotoxicity in EOC. Drug and antibody combination effects were determined by calculating the combination index values using the Chou and Talalay method. MAb216 displays direct antibody mediated cytotoxicity on a population of human EOC tumor and ascites samples and EOC cell lines, which express high amounts of poly N-acetyllactosamine epitope, carried by CD147/CD98. Eighty four percent of patient samples, including platin resistant, had a tumor population that bound the monoclonal antibody. The binding pattern of mAb216 and mechanism of cytotoxicity was similar to that seen on normal and malignant B cells with unique general membrane disruption and "pore" formation. In vitro incubation with mAb216 and cisplatin enhanced killing of OVCAR3 cell line. In EOC cell lines percent cytotoxicity correlated with percent expression of epitope. Although in vitro data shows specific EOC cytotoxicity, for possible treatment of EOC MAb216 would need to be evaluated in a clinical trial with or without chemotherapy.

Depigmented Allergoids Reveal New Epitopes with Capacity to Induce IgG Blocking Antibodies

OpenAIRE

L?pez-Matas, M. Angeles; Gallego, Mayte; Iraola, V?ctor; Robinson, Douglas; Carn?s, Jer?nimo

2013-01-01

Background. The synthesis of allergen-specific blocking IgGs that interact with IgE after allergen immunotherapy (SIT) has been related to clinical efficacy. The objectives were to investigate the epitope specificity of IgG-antibodies induced by depigmented-polymerized (Dpg-Pol) allergoids and unmodified allergen extracts, and examine IgE-blocking activity of induced IgG-antibodies. Methods. Rabbits were immunized with native and Dpg-Pol extracts of birch pollen, and serum samples were obtain...

HLA-A2 reactive antibodies in a patient who types as HLA-A2: The importance of high resolution typing and epitope-based antibody analysis.

Science.gov (United States)

Hahn, A B; Bravo-Egana, V; Jackstadt, J L; Conti, D J; Duquesnoy, R J

2015-06-01

This report describes a case of a highly sensitized patient who had serum antibodies reacting with HLA-A2 but whose phenotype included HLA-A2. The determination of HLA mismatch acceptability at the antigen level was problematic, but high-resolution HLA typing information and epitope-based antibody specificity analysis based on the nonself-self paradigm of HLA epitope immunogenicity have provided a solution. This case supports the concept that HLA typing at the allele level offers a better approach to identifying suitable donors for sensitized patients. Copyright © 2015 Elsevier B.V. All rights reserved.

Epitopes of MUC1 Tandem Repeats in Cancer as Revealed by Antibody Crystallography: Toward Glycopeptide Signature-Guided Therapy

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Dapeng Zhou

2018-05-01

Full Text Available Abnormally O-glycosylated MUC1 tandem repeat glycopeptide epitopes expressed by multiple types of cancer have long been attractive targets for therapy in the race against genetic mutations of tumor cells. Glycopeptide signature-guided therapy might be a more promising avenue than mutation signature-guided therapy. Three O-glycosylated peptide motifs, PDTR, GSTA, and GVTS, exist in a tandem repeat HGVTSAPDTRPAPGSTAPPA, containing five O-glycosylation sites. The exact peptide and sugar residues involved in antibody binding are poorly defined. Co-crystal structures of glycopeptides and respective monoclonal antibodies are very few. Here we review 3 groups of monoclonal antibodies: antibodies which only bind to peptide portion, antibodies which only bind to sugar portion, and antibodies which bind to both peptide and sugar portions. The antigenicity of peptide and sugar portions of glyco-MUC1 tandem repeat were analyzed according to available biochemical and structural data, especially the GSTA and GVTS motifs independent from the most studied PDTR. Tn is focused as a peptide-modifying residue in vaccine design, to induce glycopeptide-binding antibodies with cross reactivity to Tn-related tumor glycans, but not glycans of healthy cells. The unique requirement for the designs of antibody in antibody-drug conjugate, bi-specific antibodies, and chimeric antigen receptors are also discussed.

Targeting the autolysis loop of urokinase-type plasminogen activator with conformation-specific monoclonal antibodies.

Science.gov (United States)

Botkjaer, Kenneth A; Fogh, Sarah; Bekes, Erin C; Chen, Zhuo; Blouse, Grant E; Jensen, Janni M; Mortensen, Kim K; Huang, Mingdong; Deryugina, Elena; Quigley, James P; Declerck, Paul J; Andreasen, Peter A

2011-08-15

Tight regulation of serine proteases is essential for their physiological function, and unbalanced states of protease activity have been implicated in a variety of human diseases. One key example is the presence of uPA (urokinase-type plasminogen activator) in different human cancer types, with high levels correlating with a poor prognosis. This observation has stimulated efforts into finding new principles for intervening with uPA's activity. In the present study we characterize the so-called autolysis loop in the catalytic domain of uPA as a potential inhibitory target. This loop was found to harbour the epitopes for three conformation-specific monoclonal antibodies, two with a preference for the zymogen form pro-uPA, and one with a preference for active uPA. All three antibodies were shown to have overlapping epitopes, with three common residues being crucial for all three antibodies, demonstrating a direct link between conformational changes of the autolysis loop and the creation of a catalytically mature active site. All three antibodies are potent inhibitors of uPA activity, the two pro-uPA-specific ones by inhibiting conversion of pro-uPA to active uPA and the active uPA-specific antibody by shielding the access of plasminogen to the active site. Furthermore, using immunofluorescence, the conformation-specific antibodies mAb-112 and mAb-12E6B10 enabled us to selectively stain pro-uPA or active uPA on the surface of cultured cells. Moreover, in various independent model systems, the antibodies inhibited tumour cell invasion and dissemination, providing evidence for the feasibility of pharmaceutical intervention with serine protease activity by targeting surface loops that undergo conformational changes during zymogen activation. © The Authors Journal compilation © 2011 Biochemical Society

A human PrM antibody that recognizes a novel cryptic epitope on dengue E glycoprotein.

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Annie Hoi Yi Chan

Full Text Available Dengue virus (DENV is a major mosquito-borne pathogen infecting up to 100 million people each year; so far no effective treatment or vaccines are available. Recently, highly cross-reactive and infection-enhancing pre-membrane (prM-specific antibodies were found to dominate the anti-DENV immune response in humans, raising concern over vaccine candidates that contain native dengue prM sequences. In this study, we have isolated a broadly cross-reactive prM-specific antibody, D29, during a screen with a non-immunized human Fab-phage library against the four serotypes of DENV. The antibody is capable of restoring the infectivity of virtually non-infectious immature DENV (imDENV in FcγR-bearing K562 cells. Remarkably, D29 also cross-reacted with a cryptic epitope on the envelope (E protein located to the DI/DII junction as evidenced by site-directed mutagenesis. This cryptic epitope, while inaccessible to antibody binding in a native virus particle, may become exposed if E is not properly folded. These findings suggest that generation of anti-prM antibodies that enhance DENV infection may not be completely avoided even with immunization strategies employing E protein alone or subunits of E proteins.

Selection of SARS-Coronavirus-specific B cell epitopes by phage peptide library screening and evaluation of the immunological effect of epitope-based peptides on mice

International Nuclear Information System (INIS)

Yu Hua; Jiang Lifang; Fang Danyun; Yan Huijun; Zhou Jingjiao; Zhou Junmei; Liang Yu; Gao Yang; Zhao, Wei; Long Beiguo

2007-01-01

Antibodies to SARS-Coronavirus (SARS-CoV)-specific B cell epitopes might recognize the pathogen and interrupt its adherence to and penetration of host cells. Hence, these epitopes could be useful for diagnosis and as vaccine constituents. Using the phage-displayed peptide library screening method and purified Fab fragments of immunoglobulin G (IgG Fab) from normal human sera and convalescent sera from SARS-CoV-infected patients as targets, 11 B cell epitopes of SARS-CoV spike glycoprotein (S protein) and membrane protein (M protein) were screened. After a bioinformatics tool was used to analyze these epitopes, four epitope-based S protein dodecapeptides corresponding to the predominant epitopes were chosen for synthesis. Their antigenic specificities and immunogenicities were studied in vitro and in vivo. Flow cytometry and ELISPOT analysis of lymphocytes as well as a serologic analysis of antibody showed that these peptides could trigger a rapid, highly effective, and relatively safe immune response in BALB/c mice. These findings might aid development of SARS diagnostics and vaccines. Moreover, the role of S and M proteins as important surface antigens is confirmed

Identification, characterization, and synthesis of peptide epitopes and a recombinant six-epitope protein for Trichomonas vaginalis serodiagnosis

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Alderete JF

2013-08-01

Full Text Available J F Alderete, Calvin J NeaceSchool of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USAAbstract: There is a need for a rapid, accurate serodiagnostic test useful for both women and men infected by Trichomonas vaginalis, which causes the number one sexually transmitted infection (STI. Women and men exposed to T. vaginalis make serum antibody to fructose-1,6-bisphosphate aldolase (ALD, α-enolase (ENO, and glyceraldehyde-3-phosphate dehydrogenase (GAP. We identified, by epitope mapping, the common and distinct epitopes of each protein detected by the sera of women patients with trichomonosis and by the sera of men highly seropositive to the immunogenic protein α-actinin (positive control sera. We analyzed the amino acid sequences to determine the extent of identity of the epitopes of each protein with other proteins in the databanks. This approach identified epitopes unique to T. vaginalis, indicating these peptide-epitopes as possible targets for a serodiagnostic test. Individual or combinations of 15-mer peptide epitopes with low to no identity with other proteins were reactive with positive control sera from both women and men but were unreactive with negative control sera. These analyses permitted the synthesis of a recombinant His6 fusion protein of 111 amino acids with an Mr of ~13.4 kDa, which consisted of 15-mer peptides of two distinct epitopes each for ALD, ENO, and GAP. This recombinant protein was purified by affinity chromatography. This composite protein was detected by enzyme-linked immunosorbent assay (ELISA, dot blots, and immunoblots, using positive control sera from women and men. These data indicate that it is possible to identify epitopes and that either singly, in combination, or as a composite protein represent targets for a point-of-care serodiagnostic test for T. vaginalis.Keywords: diagnostics, point-of-care, targets, trichomonosis

Improved decision making for prioritizing tumor targeting antibodies in human xenografts: Utility of fluorescence imaging to verify tumor target expression, antibody binding and optimization of dosage and application schedule.

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Dobosz, Michael; Haupt, Ute; Scheuer, Werner

2017-01-01

Preclinical efficacy studies of antibodies targeting a tumor-associated antigen are only justified when the expression of the relevant antigen has been demonstrated. Conventionally, antigen expression level is examined by immunohistochemistry of formalin-fixed paraffin-embedded tumor tissue section. This method represents the diagnostic "gold standard" for tumor target evaluation, but is affected by a number of factors, such as epitope masking and insufficient antigen retrieval. As a consequence, variances and discrepancies in histological staining results can occur, which may influence decision-making and therapeutic outcome. To overcome these problems, we have used different fluorescence-labeled therapeutic antibodies targeting human epidermal growth factor receptor (HER) family members and insulin-like growth factor-1 receptor (IGF1R) in combination with fluorescence imaging modalities to determine tumor antigen expression, drug-target interaction, and biodistribution and tumor saturation kinetics in non-small cell lung cancer xenografts. For this, whole-body fluorescence intensities of labeled antibodies, applied as a single compound or antibody mixture, were measured in Calu-1 and Calu-3 tumor-bearing mice, then ex vivo multispectral tumor tissue analysis at microscopic resolution was performed. With the aid of this simple and fast imaging method, we were able to analyze the tumor cell receptor status of HER1-3 and IGF1R, monitor the antibody-target interaction and evaluate the receptor binding sites of anti-HER2-targeting antibodies. Based on this, the most suitable tumor model, best therapeutic antibody, and optimal treatment dosage and application schedule was selected. Predictions drawn from obtained imaging data were in excellent concordance with outcome of conducted preclinical efficacy studies. Our results clearly demonstrate the great potential of combined in vivo and ex vivo fluorescence imaging for the preclinical development and characterization of

Availability of the B beta(15-21) epitope on cross-linked human fibrin and its plasmic degradation products

Science.gov (United States)

Chen, F.; Haber, E.; Matsueda, G. R.

1992-01-01

The binding of radiolabeled monoclonal antifibrin antibody 59D8 (specific for fibrin but not fibrinogen) to a series of degraded fibrin clots showed that the availability of the B beta(15-21) epitope (against which 59D8 had been raised) was inversely proportional to the extent of clot lysis. Examination of digest supernatants revealed that the B beta(15-21) epitope was released from clots as a high molecular weight degradation product in the presence of calcium ions but that the generation of low molecular weight peptides occurred in the absence of calcium ions. To address the question of epitope accessibility, we compared levels of fibrin clot binding among four radioactively labeled antibodies: antifibrin monoclonal antibody 59D8, two antifibrinogen monoclonal antibodies that cross-reacted with fibrin, and an affinity-purified polyclonal antifibrinogen antibody. We expected that the antifibrinogen antibodies would show enhanced binding to clots in comparison with the antifibrin antibody. However, the epitope accessibility experiments showed that all four antibody preparations bound fibrin clots at comparable levels. Taken together, these studies demonstrated that one fibrin-specific epitope, B beta(15-21), remains available on clots as they undergo degradation by plasmin and, importantly, that the epitope is not solubilized at a rate faster than the rate at which the clot is itself solubilized. The availability of the B beta(15-21) epitope during the course of plasminolysis assures the potential utility of antifibrin antibodies such as 59D8 for detecting thrombi and targeting plasminogen activators.

A natural human monoclonal antibody targeting Staphylococcus Protein A protects against Staphylococcus aureus bacteremia

Science.gov (United States)

Varshney, Avanish K.; Sunley, Kevin M.; Bowling, Rodney A.; Kwan, Tzu-Yu; Mays, Heather R.; Rambhadran, Anu; Zhang, Yanfeng; Martin, Rebecca L.; Cavalier, Michael C.; Simard, John

2018-01-01

Staphylococcus aureus can cause devastating and life-threatening infections. With the increase in multidrug resistant strains, novel therapies are needed. Limited success with active and passive immunization strategies have been attributed to S. aureus immune evasion. Here, we report on a monoclonal antibody, 514G3, that circumvents a key S. aureus evasion mechanism by targeting the cell wall moiety Protein A (SpA). SpA tightly binds most subclasses of immunoglobulins via their Fc region, neutralizing effector function. The organism can thus shield itself with a protective coat of serum antibodies and render humoral immunity ineffective. The present antibody reactivity was derived from an individual with natural anti-SpA antibody titers. The monoclonal antibody is of an IgG3 subclass, which differs critically from other immunoglobulin subclasses since its Fc is not bound by SpA. Moreover, it targets a unique epitope on SpA that allows it to bind in the presence of serum antibodies. Consequently, the antibody opsonizes S. aureus and maintains effector function to enable natural immune mediated clearance. The data presented here provide evidence that 514G3 antibody is able to successfully rescue mice from S. aureus mediated bacteremia. PMID:29364906

Variable epitope libraries: new vaccine immunogens capable of inducing broad human immunodeficiency virus type 1-neutralizing antibody response.

Science.gov (United States)

Charles-Niño, Claudia; Pedroza-Roldan, Cesar; Viveros, Monica; Gevorkian, Goar; Manoutcharian, Karen

2011-07-18

The extreme antigenic variability of human immunodeficiency virus (HIV) leads to immune escape of the virus, representing a major challenge in the design of effective vaccine. We have developed a novel concept for immunogen construction based on introduction of massive mutations within the epitopes targeting antigenically variable pathogens and diseases. Previously, we showed that these immunogens carrying large combinatorial libraries of mutated epitope variants, termed as variable epitope libraries (VELs), induce potent, broad and long lasting CD8+IFN-γ+ T-cell response. Moreover, we demonstrated that these T cells recognize more than 50% of heavily mutated variants (5 out of 10 amino acid positions were mutated in each epitope variant) of HIV-1 gp120 V3 loop-derived cytotoxic T lymphocyte epitope (RGPGRAFVTI) in mice. The constructed VELs had complexities of 10000 and 12500 individual members, generated as plasmid DNA or as M13 phage display combinatorial libraries, respectively, and with structural composition RGPGXAXXXX or XGXGXAXVXI, where X is any of 20 natural amino acids. Here, we demonstrated that sera from mice immunized with these VELs are capable of neutralizing 5 out of 10 viral isolates from Tier 2 reference panel of subtype B envelope clones, including HIV-1 isolates which are known to be resistant to neutralization by several potent monoclonal antibodies, described previously. These data indicate the feasibility of the application of immunogens based on VEL concept as an alternative approach for the development of molecular vaccines against antigenically variable pathogens. Copyright © 2011 Elsevier Ltd. All rights reserved.

Production, Characterization and Use of Monoclonal Antibodies Recognizing IgY Epitopes Shared by Chicken, Turkey, Pheasant, Peafowl and Sparrow

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Ajda Biček

2004-01-01

Full Text Available Chicken antibodies are not only a part of immune defense but are more and more popular commercial products in form of chicken polyclonal, monoclonal or recombinant antibodies. We produced and characterized mouse monoclonal antibodies (mAbs that recognize epitopes located on heavy or light chain of chicken immunoglobulin Y (chIgY shared also by some other Phasianidae birds. The use of mAbs 1F5 and 2F10 that recognize heavy chain on chIgY common epitopes was demonstrated on immunoglobulins of turkey, pheasant and peafowl. Chicken IgY light chain specific mAb 3E10 revealed the presence of common epitopes on immunoglobulins of turkey, pheasant and sparrow. Monoclonal antibody clone 1F5/3G2 was used to prepare horseradish peroxidase (HRP conjugate and immunoadsorbent column. Conjugated mAbs were demonstrated to be excellent secondary antibodies for diagnostics of certain infections in different avian species. Since they do not react with mammalian immunoglobulins using our mAbs as secondary antibodies in human serodiagnostics would minimize background staining that appears when using mouse detection system. In dot immunobinding assay (DIBA and immunoblot assay they recognized specific IgY antibodies against Mycoplasma synoviae, Mycoplasma gallisepticum and Newcastle disease virus in sera of infected or vaccinated birds. Immunoadsorption as a method for removal of IgY from samples in which Mycoplasma synoviae specific IgY was predominant immunoglobulin class enabled more exact demonstration of specific IgA and IgM antibodies. Herein we are presenting effective mAbs useful in diagnostics of avian and mammalian infections as well as in final steps of detection and purification of chicken antibodies and their subunits produced in vivo or in vitro as polyclonal, monoclonal or recombinant antibodies.

Generation of neutralizing monoclonal antibodies against a conformational epitope of human adenovirus type 7 (HAdv-7 incorporated in capsid encoded in a HAdv-3-based vector.

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Minglong Liu

Full Text Available The generation of monoclonal antibodies (MAbs by epitope-based immunization is difficult because the immunogenicity of simple peptides is poor and T cells must be potently stimulated and immunological memory elicited. A strategy in which antigen is incorporated into the adenoviral capsid protein has been used previously to develop antibody responses against several vaccine targets and may offer a solution to this problem. In this study, we used a similar strategy to develop HAdv-7-neutralizing MAbs using rAdMHE3 virions into which hexon hypervariable region 5 (HVR5 of adenovirus type 7 (HAdv-7 was incorporated. The epitope mutant rAdMHE3 was generated by replacing HVR5 of Ad3EGFP, a recombinant HAdv-3-based vector expressing enhanced green fluorescence protein, with HVR5 of HAdv-7. We immunized BALB/c mice with rAdMHE3 virions and produced 22 different MAbs against them, four of which showed neutralizing activity against HAdv-7 in vitro. Using an indirect enzyme-linked immunosorbent assay (ELISA analysis and an antibody-binding-competition ELISA with Ad3EGFP, HAdv-7, and a series of chimeric adenoviral particles containing epitope mutants, we demonstrated that the four MAbs recognize the neutralization site within HVR5 of the HAdv-7 virion. Using an immunoblotting analysis and ELISA with HAdv-7, recombinant peptides, and a synthetic peptide, we also showed that the neutralizing epitope within HVR5 of the HAdv-7 virion is a conformational epitope. These findings suggest that it is feasible to use a strategy in which antigen is incorporated into the adenoviral capsid protein to generate neutralizing MAbs. This strategy may also be useful for developing therapeutic neutralizing MAbs and designing recombinant vector vaccines against HAdv-7, and in structural analysis of adenoviruses.

Characterization of Periplasmic Protein BP26 Epitopes of Brucella melitensis Reacting with Murine Monoclonal and Sheep Antibodies

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Wu, Jingbo; Zhang, Hui; Wang, Yuanzhi; Qiao, Jun; Chen, Chuangfu; Gao, Goege F.; Allain, Jean-Pierre; Li, Chengyao

2012-01-01

More than 35,000 new cases of human brucellosis were reported in 2010 by the Chinese Center for Disease Control and Prevention. An attenuated B. melitensis vaccine M5-90 is currently used for vaccination of sheep and goats in China. In the study, a periplasmic protein BP26 from M5-90 was characterized for its epitope reactivity with mouse monoclonal and sheep antibodies. A total of 29 monoclonal antibodies (mAbs) against recombinant BP26 (rBP26) were produced, which were tested for reactivity with a panel of BP26 peptides, three truncated rBP26 and native BP26 containing membrane protein extracts (NMP) of B. melitensis M5-90 in ELISA and Western-Blot. The linear, semi-conformational and conformational epitopes from native BP26 were identified. Two linear epitopes recognized by mAbs were revealed by 28 of 16mer overlapping peptides, which were accurately mapped as the core motif of amino acid residues 93DRDLQTGGI101 (position 93 to 101) or residues 104QPIYVYPD111, respectively. The reactivity of linear epitope peptides, rBP26 and NMP was tested with 137 sheep sera by ELISAs, of which the two linear epitopes had 65–70% reactivity and NMP 90% consistent with the results of a combination of two standard serological tests. The results were helpful for evaluating the reactivity of BP26 antigen in M5-90. PMID:22457830

Rapid Screening for Potential Epitopes Reactive with a Polycolonal Antibody by Solution-Phase H/D Exchange Monitored by FT-ICR Mass Spectrometry

Science.gov (United States)

Zhang, Qian; Noble, Kyle A.; Mao, Yuan; Young, Nicolas L.; Sathe, Shridhar K.; Roux, Kenneth H.; Marshall, Alan G.

2013-07-01

The potential epitopes of a recombinant food allergen protein, cashew Ana o 2, reactive to polyclonal antibodies, were mapped by solution-phase amide backbone H/D exchange (HDX) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Ana o 2 polyclonal antibodies were purified in the serum from a goat immunized with cashew nut extract. Antibodies were incubated with recombinant Ana o 2 (rAna o 2) to form antigen:polyclonal antibody (Ag:pAb) complexes. Complexed and uncomplexed (free) rAna o 2 were then subjected to HDX-MS analysis. Four regions protected from H/D exchange upon pAb binding are identified as potential epitopes and mapped onto a homologous model.

Mapping of linear antibody epitopes of the glycoprotein of VHSV, a salmonid rhabdovirus

DEFF Research Database (Denmark)

Fernandez-Alonso, M.; Lorenzo, G.; Perez, L.

1998-01-01

antibodies (MAbs), only 2 non-neutralizing MAbs, I10 (aa 139-153) and IP1H3 (aa 399-413), could be mapped to specific peptides in the pepscan of the gpG. Mapping of these MAbs was confirmed by immunoblotting with recombinant proteins and/or other synthetic peptides covering those sequences. None......Antibody Linear epitopes of the glycoprotein G (gpG) of the viral haemorrhagic septicaemia virus (VHSV), a rhabdovirus of salmonids, were mapped by pepscan using overlapping 15-mer peptides covering the entire gpG sequence and ELISA with polyclonal and monoclonal murine and polyclonal trout...... antibodies. Among the regions recognized in the pepscan by the polyclonal antibodies (PAbs) were the previously identified phosphatidylserine binding heptad-repeats (Estepa & Coll 1996; Virology 216:60-70) and leucocyte stimulating peptides (Lorenzo et al. 1995; Virology 212:348-355). Among 17 monoclonal...

A Secondary Antibody-Detecting Molecular Weight Marker with Mouse and Rabbit IgG Fc Linear Epitopes for Western Blot Analysis.

Science.gov (United States)

Lin, Wen-Wei; Chen, I-Ju; Cheng, Ta-Chun; Tung, Yi-Ching; Chu, Pei-Yu; Chuang, Chih-Hung; Hsieh, Yuan-Chin; Huang, Chien-Chiao; Wang, Yeng-Tseng; Kao, Chien-Han; Roffler, Steve R; Cheng, Tian-Lu

2016-01-01

Molecular weight markers that can tolerate denaturing conditions and be auto-detected by secondary antibodies offer great efficacy and convenience for Western Blotting. Here, we describe M&R LE protein markers which contain linear epitopes derived from the heavy chain constant regions of mouse and rabbit immunoglobulin G (IgG Fc LE). These markers can be directly recognized and stained by a wide range of anti-mouse and anti-rabbit secondary antibodies. We selected three mouse (M1, M2 and M3) linear IgG1 and three rabbit (R1, R2 and R3) linear IgG heavy chain epitope candidates based on their respective crystal structures. Western blot analysis indicated that M2 and R2 linear epitopes are effectively recognized by anti-mouse and anti-rabbit secondary antibodies, respectively. We fused the M2 and R2 epitopes (M&R LE) and incorporated the polypeptide in a range of 15-120 kDa auto-detecting markers (M&R LE protein marker). The M&R LE protein marker can be auto-detected by anti-mouse and anti-rabbit IgG secondary antibodies in standard immunoblots. Linear regression analysis of the M&R LE protein marker plotted as gel mobility versus the log of the marker molecular weights revealed good linearity with a correlation coefficient R2 value of 0.9965, indicating that the M&R LE protein marker displays high accuracy for determining protein molecular weights. This accurate, regular and auto-detected M&R LE protein marker may provide a simple, efficient and economical tool for protein analysis.

[Analysis of epitopes and function of anti-M3 muscarinic acetylcholine receptor antibodies in patients with Sjögren's syndrome].

Science.gov (United States)

Tsuboi, Hiroto; Matsuo, Naomi; Iizuka, Mana; Nakamura, Yumi; Matsumoto, Isao; Sumida, Takayuki

2010-01-01

Sjögren's syndrome (SS) is an autoimmune disease that affects exocrine glands including salivary and lacrimal glands. It is characterized by lymphocytic infiltration into exocrine glands, leading to dry mouth and eyes. A number of auto-antibodies, such as anti-SS-A and SS-B antibodies, are detected in patients with SS. However, no SS-specific pathologic auto-antibodies have yet been found in this condition. M3 muscarinic acetylcholine receptor (M3R) plays a crucial role in the secretion of saliva from salivary glands. It is reported that some patients with SS carried inhibitory auto-antibodies against M3R. To clarify the epitopes and function of anti-M3R antibodies in SS, we examined antibodies to the extracellular domains (N terminal region, the first, second, and third extracellular loop) of M3R by ELISA using synthesized peptide antigens encoding these domains in 42 SS and 42 healthy controls (HC). Titers and positivity of anti-M3R antibodies to every extracellular domain of M3R were significantly higher in SS than in HC. For functional analysis, human salivary gland (HSG) cells were pre-cultured with IgG from anti-M3R antibodies positive SS, negative SS, and HC. HSG cells were stimulated with cevimeline hydrochloride and intracellular calcium concentration ([Ca(2+)](i)) was measured. IgG from anti-M3R antibodies to the second loop positive SS inhibited the increase of [Ca(2+)](i), but IgG from antibodies to the N terminal or the first loop positive SS enhanced it, while IgG from antibodies to the third loop positive SS showed no effect on [Ca(2+)](i) as well as IgG from anti-M3R antibodies negative SS and HC. These findings indicated the presence of several B cell epitopes on M3R in SS and effect of anti-M3R antibodies on the salivary secretion might differ with these epitopes.

Vaccine-Elicited Tier 2 HIV-1 Neutralizing Antibodies Bind to Quaternary Epitopes Involving Glycan-Deficient Patches Proximal to the CD4 Binding Site.

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Ema T Crooks

2015-05-01

Full Text Available Eliciting broad tier 2 neutralizing antibodies (nAbs is a major goal of HIV-1 vaccine research. Here we investigated the ability of native, membrane-expressed JR-FL Env trimers to elicit nAbs. Unusually potent nAb titers developed in 2 of 8 rabbits immunized with virus-like particles (VLPs expressing trimers (trimer VLP sera and in 1 of 20 rabbits immunized with DNA expressing native Env trimer, followed by a protein boost (DNA trimer sera. All 3 sera neutralized via quaternary epitopes and exploited natural gaps in the glycan defenses of the second conserved region of JR-FL gp120. Specifically, trimer VLP sera took advantage of the unusual absence of a glycan at residue 197 (present in 98.7% of Envs. Intriguingly, removing the N197 glycan (with no loss of tier 2 phenotype rendered 50% or 16.7% (n = 18 of clade B tier 2 isolates sensitive to the two trimer VLP sera, showing broad neutralization via the surface masked by the N197 glycan. Neutralizing sera targeted epitopes that overlap with the CD4 binding site, consistent with the role of the N197 glycan in a putative "glycan fence" that limits access to this region. A bioinformatics analysis suggested shared features of one of the trimer VLP sera and monoclonal antibody PG9, consistent with its trimer-dependency. The neutralizing DNA trimer serum took advantage of the absence of a glycan at residue 230, also proximal to the CD4 binding site and suggesting an epitope similar to that of monoclonal antibody 8ANC195, albeit lacking tier 2 breadth. Taken together, our data show for the first time that strain-specific holes in the glycan fence can allow the development of tier 2 neutralizing antibodies to native spikes. Moreover, cross-neutralization can occur in the absence of protecting glycan. Overall, our observations provide new insights that may inform the future development of a neutralizing antibody vaccine.

Epitope-dependent mechanisms of CD27 neutralization revealed by X-ray crystallography

Energy Technology Data Exchange (ETDEWEB)

Obmolova, Galina; Teplyakov, Alexey; Malia, Thomas J.; Wunderler, Nicole; Kwok, Deborah; Barone, Linda; Sweet, Raymond; Ort, Tatiana; Scully, Michael; Gilliland, Gary L. (Janssen)

2017-03-01

CD27 is a T and B cell co-stimulatory protein of the TNF receptor superfamily dependent on the availability of the TNF-like ligand CD70. Two anti-CD27 neutralizing monoclonal antibodies were obtained from mouse hybridoma and subsequently humanized and optimized for binding the target. The two antibodies are similar in terms of their CD27-binding affinity and ability to block NF-κB signaling, however their clearance rates in monkeys are very different. The pharmacokinetics profiles could be epitope dependent. To identify the epitopes, we determined the crystal structure of the ternary complex between CD27 and the Fab fragments of these non-competing antibodies. The structure reveals the binding modes of the antibodies suggesting that their mechanisms of action are distinctly different and provides a possible explanation of the in vivo data.

Optimal selection of epitopes for TXP-immunoaffinity mass spectrometry.

Science.gov (United States)

Planatscher, Hannes; Supper, Jochen; Poetz, Oliver; Stoll, Dieter; Joos, Thomas; Templin, Markus F; Zell, Andreas

2010-06-25

Mass spectrometry (MS) based protein profiling has become one of the key technologies in biomedical research and biomarker discovery. One bottleneck in MS-based protein analysis is sample preparation and an efficient fractionation step to reduce the complexity of the biological samples, which are too complex to be analyzed directly with MS. Sample preparation strategies that reduce the complexity of tryptic digests by using immunoaffinity based methods have shown to lead to a substantial increase in throughput and sensitivity in the proteomic mass spectrometry approach. The limitation of using such immunoaffinity-based approaches is the availability of the appropriate peptide specific capture antibodies. Recent developments in these approaches, where subsets of peptides with short identical terminal sequences can be enriched using antibodies directed against short terminal epitopes, promise a significant gain in efficiency. We show that the minimal set of terminal epitopes for the coverage of a target protein list can be found by the formulation as a set cover problem, preceded by a filtering pipeline for the exclusion of peptides and target epitopes with undesirable properties. For small datasets (a few hundred proteins) it is possible to solve the problem to optimality with moderate computational effort using commercial or free solvers. Larger datasets, like full proteomes require the use of heuristics.

A synthetic peptide derived from the animo acid sequence of canine parvovirus structural proteins which defines a B cell epitope and elicits antiviral antibody in BALB c mice.

NARCIS (Netherlands)

G.F. Rimmelzwaan (Guus); J. Carlson; F.G.C.M. Uytdehaag (Fons); A.D.M.E. Osterhaus (Albert)

1990-01-01

textabstractSynthetic peptides, recombinant fusion proteins and mouse monoclonal antibodies were used to delineate a B cell epitope of the VP'2 structural protein of canine parvovirus (CPV). Although this epitope is not preferentially recognized in the normal antibody response to CPV, virus-specific

Routinely used immunoassays do not detect circulating anti-GBM antibodies against native NC1 hexamer and EA epitope of the α3 chain of type IV collagen.

Science.gov (United States)

Clavarino, Giovanna; Gauthier, Arnaud; Hellmark, Thomas; Carron, Pierre-Louis; Giovannini, Diane; Colliard, Sophie; Dragon-Durey, Marie-Agnès; Segelmark, Mårten; Cesbron, Jean-Yves; Dumestre-Pérard, Chantal

2018-04-12

Detection of circulating anti-GBM antibodies has a key role for the diagnosis of Goodpasture syndrome but immunoassays using purified or recombinant alpha3(IV)NC1 as antigen do not recognize all anti-GBM antibodies. We show that anti-GBM antibodies directed against epitopes in their native conformation or cryptic epitopes are detected by indirect immunofluorescence. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Screening and identification of T helper 1 and linear immunodominant antibody-binding epitopes in the spike 2 domain and the nucleocapsid protein of feline infectious peritonitis virus.

Science.gov (United States)

Satoh, Ryoichi; Furukawa, Tomoko; Kotake, Masako; Takano, Tomomi; Motokawa, Kenji; Gemma, Tsuyoshi; Watanabe, Rie; Arai, Setsuo; Hohdatsu, Tsutomu

2011-02-17

The antibody-dependent enhancement (ADE) of feline infectious peritonitis virus (FIPV) infection has been recognized in experimentally infected cats, and cellular immunity is considered to play an important role in preventing the onset of feline infectious peritonitis (FIP). In the present study, we synthesized eighty-one kinds of peptides derived from the spike (S)2 domain of type I FIPV KU-2 strain, the S2 domain of type II FIPV 79-1146 strain, and the nucleocapcid (N) protein of FIPV KU-2 strain. To detect the T helper (Th)1 epitope, peripheral blood mononuclear cells (PBMCs) obtained from FIPV-infected cats were cultured with each peptide, and Th1-type immune responses were measured using feline interferon (fIFN)-γ production as an index. To detect the linear immunodominant antibody-binding epitope, we investigated the reactivity of plasma collected from FIPV-infected cats against each peptide by ELISA. Four and 2 peptides containing Th1 epitopes were identified in the heptad repeat (HR)1 and inter-helical (IH) regions of the S2 domain of type I FIPV, respectively, and these were located on the N-terminal side of the regions. In the S2 domain of type II FIPV, 2, 3, and 2 peptides containing Th1 epitopes were identified in the HR1, IH, and HR2 regions, respectively, and these were mainly located on the C-terminal side of the regions. In the S2 domain of type I FIPV, 3 and 7 peptides containing linear immunodominant antibody-binding epitopes were identified in the IH and HR2 regions, respectively. In the S2 domain of type II FIPV, 4 peptides containing linear immunodominant antibody-binding epitopes were identified in the HR2 region. The Th1 epitopes in the S2 domain of type I and II FIPV were located in different regions, but the linear immunodominant antibody-binding epitopes were mostly located in the HR2 region. Eight peptides containing Th1 epitopes were identified in N protein, and 3 peptides derived from residues 81 to 100 and 137 to 164 showed strong

Epitope-Targeting of Tertiary Protein Structure Enables Target-Guided Synthesis of a Potent in Cell Inhibitor of Botulinum Neurotoxin**

OpenAIRE

Farrow, Blake; Wong, Michelle; Malette, Jacquie; Lai, Bert; Deyle, Kaycie M.; Das, Samir; Nag, Arundhati; Agnew, Heather D.; Heath, James R.

2015-01-01

Botulinum neurotoxin (BoNT) serotype A is the most lethal known toxin and has an occluded structure, which prevents direct inhibition of its active site before it enters the cytosol. Target-guided synthesis by in situ click chemistry is combined with synthetic epitope targeting to exploit the tertiary structure of the BoNT protein as a landscape for assembling a competitive inhibitor. A substrate-mimicking peptide macrocycle is used as a direct inhibitor of BoNT. An epitope-targeting in situ ...

Antibody Selection for Cancer Target Validation of FSH-Receptor in Immunohistochemical Settings

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Nina Moeker

2017-10-01

Full Text Available Background: The follicle-stimulating hormone (FSH-receptor (FSHR has been reported to be an attractive target for antibody therapy in human cancer. However, divergent immunohistochemical (IHC findings have been reported for FSHR expression in tumor tissues, which could be due to the specificity of the antibodies used. Methods: Three frequently used antibodies (sc-7798, sc-13935, and FSHR323 were validated for their suitability in an immunohistochemical study for FSHR expression in different tissues. As quality control, two potential therapeutic anti-hFSHR Ylanthia® antibodies (Y010913, Y010916 were used. The specificity criteria for selection of antibodies were binding to native hFSHR of different sources, and no binding to non-related proteins. The ability of antibodies to stain the paraffin-embedded Flp-In Chinese hamster ovary (CHO/FSHR cells was tested after application of different epitope retrieval methods. Results: From the five tested anti-hFSHR antibodies, only Y010913, Y010916, and FSHR323 showed specific binding to native, cell-presented hFSHR. Since Ylanthia® antibodies were selected to specifically recognize native FSHR, as required for a potential therapeutic antibody candidate, FSHR323 was the only antibody to detect the receptor in IHC/histochemical settings on transfected cells, and at markedly lower, physiological concentrations (ex., in Sertoli cells of human testes. The pattern of FSH323 staining noticed for ovarian, prostatic, and renal adenocarcinomas indicated that FSHR was expressed mainly in the peripheral tumor blood vessels. Conclusion: Of all published IHC antibodies tested, only antibody FSHR323 proved suitable for target validation of hFSHR in an IHC setting for cancer. Our studies could not confirm the previously reported FSHR overexpression in ovarian and prostate cancer cells. Instead, specific overexpression in peripheral tumor blood vessels could be confirmed after thorough validation of the antibodies used.

Recombinant Protein Containing B-Cell Epitopes of Different Loxosceles Spider Toxins Generates Neutralizing Antibodies in Immunized Rabbits.

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Lima, Sabrina de Almeida; Guerra-Duarte, Clara; Costal-Oliveira, Fernanda; Mendes, Thais Melo; Figueiredo, Luís F M; Oliveira, Daysiane; Machado de Avila, Ricardo A; Ferrer, Valéria Pereira; Trevisan-Silva, Dilza; Veiga, Silvio S; Minozzo, João C; Kalapothakis, Evanguedes; Chávez-Olórtegui, Carlos

2018-01-01

Loxoscelism is the most important form of araneism in South America. The treatment of these accidents uses heterologous antivenoms obtained from immunization of production animals with crude loxoscelic venom. Due to the scarcity of this immunogen, new alternatives for its substitution in antivenom production are of medical interest. In the present work, three linear epitopes for Loxosceles astacin-like protease 1 (LALP-1) (SLGRGCTDFGTILHE, ENNTRTIGPFDYDSIMLYGAY, and KLYKCPPVNPYPGGIRPYVNV) and two for hyaluronidase (LiHYAL) (NGGIPQLGDLKAHLEKSAVDI and ILDKSATGLRIIDWEAWR) from Loxosceles intermedia spider venom were identified by SPOT-synthesis technique. One formerly characterized linear epitope (DFSGPYLPSLPTLDA) of sphingomyelinase D (SMase D) SMase-I from Loxosceles laeta was also chosen to constitute a new recombinant multiepitopic protein. These epitopes were combined with a previously produced chimeric multiepitopic protein (rCpLi) composed by linear and conformational B-cell epitopes from SMase D from L. intermedia venom, generating a new recombinant multiepitopic protein derived from loxoscelic toxins (rMEPLox). We demonstrated that rMEPLox is non-toxic and antibodies elicited in rabbits against this antigen present reactivity in ELISA and immunoblot assays with Brazilian L. intermedia, L. laeta, L. gaucho , and L. similis spider venoms. In vivo and in vitro neutralization assays showed that anti-rMEPLox antibodies can efficiently neutralize the sphingomyelinase, hyaluronidase, and metalloproteinase activity of L. intermedia venom. This study suggests that this multiepitopic protein can be a suitable candidate for experimental vaccination approaches or for antivenom production against Loxosceles spp. venoms.

Recombinant Protein Containing B-Cell Epitopes of Different Loxosceles Spider Toxins Generates Neutralizing Antibodies in Immunized Rabbits

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Lima, Sabrina de Almeida; Guerra-Duarte, Clara; Costal-Oliveira, Fernanda; Mendes, Thais Melo; Figueiredo, Luís F. M.; Oliveira, Daysiane; Machado de Avila, Ricardo A.; Ferrer, Valéria Pereira; Trevisan-Silva, Dilza; Veiga, Silvio S.; Minozzo, João C.; Kalapothakis, Evanguedes; Chávez-Olórtegui, Carlos

2018-01-01

Loxoscelism is the most important form of araneism in South America. The treatment of these accidents uses heterologous antivenoms obtained from immunization of production animals with crude loxoscelic venom. Due to the scarcity of this immunogen, new alternatives for its substitution in antivenom production are of medical interest. In the present work, three linear epitopes for Loxosceles astacin-like protease 1 (LALP-1) (SLGRGCTDFGTILHE, ENNTRTIGPFDYDSIMLYGAY, and KLYKCPPVNPYPGGIRPYVNV) and two for hyaluronidase (LiHYAL) (NGGIPQLGDLKAHLEKSAVDI and ILDKSATGLRIIDWEAWR) from Loxosceles intermedia spider venom were identified by SPOT-synthesis technique. One formerly characterized linear epitope (DFSGPYLPSLPTLDA) of sphingomyelinase D (SMase D) SMase-I from Loxosceles laeta was also chosen to constitute a new recombinant multiepitopic protein. These epitopes were combined with a previously produced chimeric multiepitopic protein (rCpLi) composed by linear and conformational B-cell epitopes from SMase D from L. intermedia venom, generating a new recombinant multiepitopic protein derived from loxoscelic toxins (rMEPLox). We demonstrated that rMEPLox is non-toxic and antibodies elicited in rabbits against this antigen present reactivity in ELISA and immunoblot assays with Brazilian L. intermedia, L. laeta, L. gaucho, and L. similis spider venoms. In vivo and in vitro neutralization assays showed that anti-rMEPLox antibodies can efficiently neutralize the sphingomyelinase, hyaluronidase, and metalloproteinase activity of L. intermedia venom. This study suggests that this multiepitopic protein can be a suitable candidate for experimental vaccination approaches or for antivenom production against Loxosceles spp. venoms. PMID:29666624

Identification of epitopes within integrin β4 for binding of auto-antibodies in ocular cicatricial and mucous membrane pemphigoid: preliminary report.

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Rashid, Khwaja Aftab; Foster, C Stephen; Ahmed, A Razzaque

2013-11-19

To identify the epitopes on human β4 integrin to which the sera of patients with ocular cicatricial pemphigoid (OCP) and mucous membrane pemphigoid (MMP) without ocular involvement bind. Fragments of the intracellular domain of the β4 molecule were cloned, expressed, purified and peptides were synthesized. Antibodies to various fragments and peptides were produced in rabbits. Binding specificity was determined via Western blot and blocking experiments. Test sera and controls were injected into neonatal BALB/c mice for in vivo passive transfer. Sera from patients with OCP, MMP, and both OCP and MMP were bound to cloned fragments of IC3.0. Its subcloned fragments IC3.4 (1489 aa-1572 aa) and IC3.4.1 (1489 aa-1510 aa) were bound with the sera from patients with OCP only. Subcloned fragments IC3.6 (1573 aa-1822 aa) and IC3.6.1 (1689 aa-1702 aa) were bound with MMP sera only. No cross-reactivity in binding was observed. Immuno-affinity-purified sera from patients with OCP, MMP, and rabbit antibodies to IC3.0, IC3.4, IC3.4.1, IC3.6, and IC3.6.1, when injected in neonatal BALB/c mice, produced subepidermal blisters in their skin. These preliminary observations identified IC3.4.1 as the possible epitope for the binding of OCP auto-antibody and IC3.6.1 as the possible epitope for the binding of MMP auto-antibody without ocular disease. Antibodies specific to these peptides produced blisters when injected in mice. Still-unidentified epitopes may exist. These observations may enhance our understanding of the role of β4 integrin in the pathobiology of OCP and MMP. Early diagnosis may be possible if serologic tests with specificity and sensitivity can be developed.

Mapping the epitopes of a neutralizing antibody fragment directed against the lethal factor of Bacillus anthracis and cross-reacting with the homologous edema factor.

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Philippe Thullier

Full Text Available The lethal toxin (LT of Bacillus anthracis, composed of the protective antigen (PA and the lethal factor (LF, plays an essential role in anthrax pathogenesis. PA also interacts with the edema factor (EF, 20% identity with LF to form the edema toxin (ET, which has a lesser role in anthrax pathogenesis. The first recombinant antibody fragment directed against LF was scFv 2LF; it neutralizes LT by blocking the interaction between PA and LF. Here, we report that scFv 2LF cross-reacts with EF and cross-neutralizes ET, and we present an in silico method taking advantage of this cross-reactivity to map the epitope of scFv 2LF on both LF and EF. This method identified five epitope candidates on LF, constituted of a total of 32 residues, which were tested experimentally by mutating the residues to alanine. This combined approach precisely identified the epitope of scFv 2LF on LF as five residues (H229, R230, Q234, L235 and Y236, of which three were missed by the consensus epitope candidate identified by pre-existing in silico methods. The homolog of this epitope on EF (H253, R254, E258, L259 and Y260 was experimentally confirmed to constitute the epitope of scFv 2LF on EF. Other inhibitors, including synthetic molecules, could be used to target these epitopes for therapeutic purposes. The in silico method presented here may be of more general interest.

A Rationally Designed TNF-α Epitope-Scaffold Immunogen Induces Sustained Antibody Response and Alleviates Collagen-Induced Arthritis in Mice.

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Li Zhang

Full Text Available The TNF-α biological inhibitors have significantly improved the clinical outcomes of many autoimmune diseases, in particular rheumatoid arthritis. However, the practical uses are limited due to high costs and the risk of anti-drug antibody responses. Attempts to develop anti-TNF-α vaccines have generated encouraging data in animal models, however, data from clinical trials have not met expectations. In present study, we designed a TNF-α epitope-scaffold immunogen DTNF7 using the transmembrane domain of diphtheria toxin, named DTT as a scaffold. Molecular dynamics simulation shows that the grafted TNF-α epitope is entirely surface-exposed and presented in a native-like conformation while the rigid helical structure of DTT is minimally perturbed, thereby rendering the immunogen highly stable. Immunization of mice with alum formulated DTNF7 induced humoral responses against native TNF-α, and the antibody titer was sustained for more than 6 months, which supports a role of the universal CD4 T cell epitopes of DTT in breaking self-immune tolerance. In a mouse model of rheumatoid arthritis, DTNF7-alum vaccination markedly delayed the onset of collagen-induced arthritis, and reduced incidence as well as clinical score. DTT is presumed safe as an epitope carrier because a catalytic inactive mutant of diphtheria toxin, CRM197 has good clinical safety records as an active vaccine component. Taken all together, we show that DTT-based epitope vaccine is a promising strategy for prevention and treatment of autoimmune diseases.

A Conserved Epitope Mapped with a Monoclonal Antibody against the VP3 Protein of Goose Parvovirus by Using Peptide Screening and Phage Display Approaches.

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Li, Chenxi; Liu, Hongyu; Li, Jinzhe; Liu, Dafei; Meng, Runze; Zhang, Qingshan; Shaozhou, Wulin; Bai, Xiaofei; Zhang, Tingting; Liu, Ming; Zhang, Yun

2016-01-01

Waterfowl parvovirus (WPV) infection causes high mortality and morbidity in both geese (Anser anser) and Muscovy ducks (Cairina moschata), resulting in significant losses to the waterfowl industries. The VP3 protein of WPV is a major structural protein that induces neutralizing antibodies in the waterfowl. However, B-cell epitopes on the VP3 protein of WPV have not been characterized. To understand the antigenic determinants of the VP3 protein, we used the monoclonal antibody (mAb) 4A6 to screen a set of eight partially expressed overlapping peptides spanning VP3. Using western blotting and an enzyme-linked immunosorbent assay (ELISA), we localized the VP3 epitope between amino acids (aa) 57 and 112. To identify the essential epitope residues, a phage library displaying 12-mer random peptides was screened with mAb 4A6. Phage clone peptides displayed a consensus sequence of YxRFHxH that mimicked the sequence 82Y/FNRFHCH88, which corresponded to amino acid residues 82 to 88 of VP3 protein of WPVs. mAb 4A6 binding to biotinylated fragments corresponding to amino acid residues 82 to 88 of the VP3 protein verified that the 82FxRFHxH88 was the VP3 epitope and that amino acids 82F is necessary to retain maximal binding to mAb 4A6. Parvovirus-positive goose and duck sera reacted with the epitope peptide by dot blotting assay, revealing the importance of these amino acids of the epitope in antibody-epitope binding reactivity. We identified the motif FxRFHxH as a VP3-specific B-cell epitope that is recognized by the neutralizing mAb 4A6. This finding might be valuable in understanding of the antigenic topology of VP3 of WPV.

Generation and epitope analysis of human monoclonal antibody isotypes with specificity for the timothy grass major allergen Phl p 5a

DEFF Research Database (Denmark)

Hecker, J.; Diethers, A.; Seismann, H.

2011-01-01

The scarcity of monoclonal human IgE antibodies with specificity for defined allergens is a bottleneck for the molecular characterisation of allergens and their epitopes. Insights into the characteristics of such antibodies may allow for analyses of the molecular basis underlying allergenicity an...

A surface plasmon resonance assay for characterisation and epitope mapping of anti-GLP-1 antibodies.

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Thomsen, Lasse; Gurevich, Leonid

2018-04-19

The incretin hormone glucagon-like peptide-1 (GLP-1) has been subject to substantial pharmaceutical research regarding the treatment of type 2 diabetes mellitus. However, quantification of GLP-1 levels remains complicated due to the low circulation concentration and concurrent existence of numerous metabolites, homologous peptides, and potentially introduced GLP-1 receptor agonists. Surface plasmon resonance (SPR) facilitates real-time monitoring allowing a more detailed characterisation of the interaction compared with conventional enzyme-linked immunosorbent assays (ELISA). In this paper, we describe the development of the first SPR assays for characterisation of anti-GLP-1 antibodies for ELISA purposes. Binding responses were obtained on covalently immobilised anti-GLP-1 antibodies at 12°C, 25°C, and 40°C and fitted to a biomolecular (1:1) interaction model showing association rates of 1.01 × 10 3 to 4.54 × 10 3  M -1  s -1 and dissociation rates of 3.56 × 10 -5 to 1.56 × 10 -3  s -1 leading to affinities of 35.2 to 344 nM, depending on the temperature. Determination of thermodynamic properties revealed an enthalpy driven interaction (ΔH polar amino acids (ΔC p  < 0). Pair-wise epitope mapping was performed on captured anti-GLP-1 antibodies followed by subsequent interaction with GLP-1 (7-36) and other anti-GLP-1 antibodies. A global evaluation of every binding response led to an epitope map elucidating the potential of various anti-GLP-1 antibody pairs for sandwich ELISA and hence pinpointing the optimal antibody combinations. The SPR assays proved capable of providing vital information for ELISA development endorsing it as a useful optimisation tool. Copyright © 2018 John Wiley & Sons, Ltd.

New epitopes and function of anti-M3 muscarinic acetylcholine receptor antibodies in patients with Sjögren's syndrome.

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Tsuboi, H; Matsumoto, I; Wakamatsu, E; Nakamura, Y; Iizuka, M; Hayashi, T; Goto, D; Ito, S; Sumida, T

2010-10-01

M3 muscarinic acetylcholine receptor (M3R) plays a crucial role in the secretion of saliva from salivary glands. It is reported that some patients with Sjögren's syndrome (SS) carried inhibitory autoantibodies against M3R. The purpose of this study is to clarify the epitopes and function of anti-M3R antibodies in SS. We synthesized peptides encoding the extracellular domains of human-M3R including the N-terminal region and the first, second and third extracellular loops. Antibodies against these regions were examined by enzyme-linked immunosorbent assay in sera from 42 SS and 42 healthy controls. For functional analysis, human salivary gland (HSG) cells were preincubated with immunoglobulin G (IgG) separated from sera of anti-M3R antibody-positive SS, -negative SS and controls for 12 h. After loading with Fluo-3, HSG cells were stimulated with cevimeline hydrochloride, and intracellular Ca(2+) concentrations [(Ca(2+) )i] were measured. Antibodies to the N-terminal, first, second and third loops were detected in 42·9% (18 of 42), 47·6% (20 of 42), 54·8% (23 of 42) and 45·2% (19 of 42) of SS, while in 4·8% (two of 42), 7·1% (three of 42), 2·4% (one of 42) and 2·4% (one of 42) of controls, respectively. Antibodies to the second loop positive SS-IgG inhibited the increase of (Ca(2+) )i induced by cevimeline hydrochloride. Antibodies to the N-terminal positive SS-IgG and antibodies to the first loop positive SS-IgG enhanced it, while antibodies to the third loop positive SS-IgG showed no effect on (Ca(2+) )i as well as anti-M3R antibody-negative SS-IgG. Our results indicated the presence of several B cell epitopes on M3R in SS. The influence of anti-M3R antibodies on salivary secretion might differ based on these epitopes. © 2010 The Authors. Clinical and Experimental Immunology © 2010 British Society for Immunology.

Directed Selection of Recombinant Human Monoclonal Antibodies to Herpes Simplex Virus Glycoproteins from Phage Display Libraries

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Sanna, Pietro Paolo; Williamson, R. Anthony; de Logu, Alessandro; Bloom, Floyd E.; Burton, Dennis R.

1995-07-01

Human monoclonal antibodies have considerable potential in the prophylaxis and treatment of viral disease. However, only a few such antibodies suitable for clinical use have been produced to date. We have previously shown that large panels of human recombinant monoclonal antibodies against a plethora of infectious agents, including herpes simplex virus types 1 and 2, can be established from phage display libraries. Here we demonstrate that facile cloning of recombinant Fab fragments against specific viral proteins in their native conformation can be accomplished by panning phage display libraries against viral glycoproteins "captured" from infected cell extracts by specific monoclonal antibodies immobilized on ELISA plates. We have tested this strategy by isolating six neutralizing recombinant antibodies specific for herpes simplex glycoprotein gD or gB, some of which are against conformationally sensitive epitopes. By using defined monoclonal antibodies for the antigen-capture step, this method can be used for the isolation of antibodies to specific regions and epitopes within the target viral protein. For instance, monoclonal antibodies to a nonneutralizing epitope can be used in the capture step to clone antibodies to neutralizing epitopes, or antibodies to a neutralizing epitope can be used to clone antibodies to a different neutralizing epitope. Furthermore, by using capturing antibodies to more immunodominant epitopes, one can direct the cloning to less immunogenic ones. This method should be of value in generating antibodies to be used both in the prophylaxis and treatment of viral infections and in the characterization of the mechanisms of antibody protective actions at the molecular level.

Epitope mapping of the alpha-chain of the insulin-like growth factor I receptor using antipeptide antibodies.

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Delafontaine, P; Ku, L; Ververis, J J; Cohen, C; Runge, M S; Alexander, R W

1994-12-01

Insulin-like growth factor I (IGF I) is an important mitogen for vascular smooth muscle cells (VSMC). The IGF I receptor (IGF IR) is a heterotetramer composed of two cross-linked extracellular alpha-chains and two membrane-spanning beta-chains that contain a tyrosine-kinase domain. It has a high degree of sequence similarity to the insulin receptor (IR), and the putative ligand-specific binding site has been localized to a cysteine-rich region (CRR) of the alpha-chain. To obtain insights into antigenic determinants of the IGF IR, we raised a panel of site-specific polyclonal antibodies against short peptide sequences N-terminal to and within the CRR. Several antibodies raised against linear epitopes within the CRR bound to solubilized and native rat and human IGF IR by ELISA, did not cross-react with IR, but unexpectedly failed to inhibit 125I-IGF I binding. A polyclonal antibody directed against a 48-amino acid synthetic peptide, corresponding to a region of the CRR postulated to be essential for ligand binding, failed to react with either solubilized, reduced or intact IGF IR. Three antibodies specific for the N-terminus of the alpha-chain reacted with solubilized and native IGF IR. One of these, RAB 6, directed against amino acids 38-44 of the IGF IR, inhibited 125I-IGF I binding to rat aortic smooth muscle cells (RASM) and to IGF IR/3T3 cells (overexpressing human IGF IR) by up to 45%. Immunohistochemical analysis revealed strong IGF IR staining in the medial smooth muscle cell layer of rat aorta. These findings are consistent with a model wherein conformational epitopes within the CRR and linear epitopes within the N-terminus of the alpha-chain contribute to the IGF I binding pocket. These antibodies should provide a valuable tool to study structure-function relationships and in vivo regulation of the IGF IR.

Identification of a novel canine distemper virus B-cell epitope using a monoclonal antibody against nucleocapsid protein.

Science.gov (United States)

Yi, Li; Cheng, Yuening; Zhang, Miao; Cao, Zhigang; Tong, Mingwei; Wang, Jianke; Zhao, Hang; Lin, Peng; Cheng, Shipeng

2016-02-02

Canine distemper virus (CDV) is a member of the genus Morbillivirus within the family Paramyxoviridae and has caused severe economic losses in China. Nucleocapsid protein (N) is the major structural viral protein and can be used to diagnose CDV and other morbilliviruses. In this study, a specific monoclonal antibody, 1N8, was produced against the CDV N protein (amino acids 277-471). A linear N protein epitope was identified by subjecting a series of partially overlapping synthesized peptides to enzyme-linked immunosorbent assay (ELISA) analysis. The results indicated that (350)LNFGRSYFDPA(360) was the minimal linear epitope that could be recognized by mAb 1N8. ELISA assays revealed that mouse anti-CDV sera could also recognize the minimal linear epitope. Alignment analysis of the amino acid sequences indicated that the epitope was highly conserved among CDV strains. Furthermore, the epitope was conserved among other morbilliviruses, which was confirmed with PRRV using western blotting. Taken together, the results of this study may have potential applications in the development of suitable diagnostic techniques for CDV or other morbilliviruses. Copyright © 2015 Elsevier B.V. All rights reserved.

Human Monoclonal Islet Cell Antibodies From a Patient with Insulin- Dependent Diabetes Mellitus Reveal Glutamate Decarboxylase as the Target Antigen

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Richter, Wiltrud; Endl, Josef; Eiermann, Thomas H.; Brandt, Michael; Kientsch-Engel, Rosemarie; Thivolet, Charles; Jungfer, Herbert; Scherbaum, Werner A.

1992-09-01

The autoimmune phenomena associated with destruction of the β cell in pancreatic islets and development of type 1 (insulin-dependent) diabetes mellitus (IDDM) include circulating islet cell antibodies. We have immortalized peripheral blood lymphocytes from prediabetic individuals and patients with newly diagnosed IDDM by Epstein-Barr virus transformation. IgG-positive cells were selected by anti-human IgG-coupled magnetic beads and expanded in cell culture. Supernatants were screened for cytoplasmic islet cell antibodies using the conventional indirect immunofluorescence test on cryostat sections of human pancreas. Six islet cell-specific B-cell lines, originating from a patient with newly diagnosed IDDM, could be stabilized on a monoclonal level. All six monoclonal islet cell antibodies (MICA 1-6) were of the IgG class. None of the MICA reacted with human thyroid, adrenal gland, anterior pituitary, liver, lung, stomach, and intestine tissues but all six reacted with pancreatic islets of different mammalian species and, in addition, with neurons of rat cerebellar cortex. MICA 1-6 were shown to recognize four distinct antigenic epitopes in islets. Islet cell antibody-positive diabetic sera but not normal human sera blocked the binding of the monoclonal antibodies to their target epitopes. Immunoprecipitation of 35S-labeled human islet cell extracts revealed that a protein of identical size to the enzyme glutamate decarboxylase (EC 4.1.1.15) was a target of all MICA. Furthermore, antigen immunotrapped by the MICA from brain homogenates showed glutamate decarboxylase enzyme activity. MICA 1-6 therefore reveal glutamate decarboxylase as the predominant target antigen of cytoplasmic islet cell autoantibodies in a patient with newly diagnosed IDDM.

Immunotherapy for Alzheimer's disease: DNA- and protein-based epitope vaccines.

Science.gov (United States)

Davtyan, Hayk; Petrushina, Irina; Ghochikyan, Anahit

2014-01-01

Active immunotherapy for Alzheimer's disease (AD) is aimed to induce antibodies specific to amyloid-beta (Aβ) that are capable to reduce the level of Aβ in the CNS of Alzheimer's disease patients. First clinical trial AN-1792 that was based on vaccination with full-length Aβ42 showed that safe and effective AD vaccine should induce high titers of anti-Aβ antibodies without activation of harmful autoreactive T cells. Replacement of self-T cell epitope with foreign epitope, keeping self-B cell epitope intact, may allow to induce high titers of anti-Aβ antibodies while avoiding the activation of T cells specific to Aβ. Here we describe the protocols for evaluation of AD DNA- or multiple antigenic peptide (MAP)-based epitope vaccines composed of Aβ(1-11) B cell epitope fused to synthetic T cell epitope PADRE (Aβ(1-11)-PADRE). All protocols could be used for testing any epitope vaccine constructed in your lab and composed of other T cell epitopes using the appropriate peptides in tests for evaluation of humoral and cellular immune responses.

Confirmation of a new conserved linear epitope of Lyssavirus nucleoprotein.

Science.gov (United States)

Xinjun, Lv; Xuejun, Ma; Lihua, Wang; Hao, Li; Xinxin, Shen; Pengcheng, Yu; Qing, Tang; Guodong, Liang

2012-05-01

Bioinformatics analysis was used to predict potential epitopes of Lyssavirus nucleoprotein and highlighted some distinct differences in the quantity and localization of the epitopes disclosed by epitope analysis of monoclonal antibodies against Lyssavirus nucleoprotein. Bioinformatics analysis showed that the domain containing residues 152-164 of Lyssavirus nucleoprotein was a conserved linear epitope that had not been reported previously. Immunization of two rabbits with the corresponding synthetic peptide conjugated to the Keyhole Limpe hemocyanin (KLH) macromolecule resulted in a titer of anti-peptide antibody above 1:200,000 in rabbit sera as detected by indirect enzyme-linked immunosorbent assay (ELISA). Western blot analysis demonstrated that the anti-peptide antibody recognized denatured Lyssavirus nucleoprotein in sodium dodecylsulfonate-polyacrylate gel electrophoresis (SDS-PAGE). Affinity chromatography purification and FITC-labeling of the anti-peptide antibody in rabbit sera was performed. FITC-labeled anti-peptide antibody could recognize Lyssavirus nucleoprotein in BSR cells and canine brain tissues even at a 1:200 dilution. Residues 152-164 of Lyssavirus nucleoprotein were verified as a conserved linear epitope in Lyssavirus. Copyright © 2012 Elsevier B.V. All rights reserved.

Optimal selection of epitopes for TXP-immunoaffinity mass spectrometry

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Joos Thomas

2010-06-01

Full Text Available Abstract Background Mass spectrometry (MS based protein profiling has become one of the key technologies in biomedical research and biomarker discovery. One bottleneck in MS-based protein analysis is sample preparation and an efficient fractionation step to reduce the complexity of the biological samples, which are too complex to be analyzed directly with MS. Sample preparation strategies that reduce the complexity of tryptic digests by using immunoaffinity based methods have shown to lead to a substantial increase in throughput and sensitivity in the proteomic mass spectrometry approach. The limitation of using such immunoaffinity-based approaches is the availability of the appropriate peptide specific capture antibodies. Recent developments in these approaches, where subsets of peptides with short identical terminal sequences can be enriched using antibodies directed against short terminal epitopes, promise a significant gain in efficiency. Results We show that the minimal set of terminal epitopes for the coverage of a target protein list can be found by the formulation as a set cover problem, preceded by a filtering pipeline for the exclusion of peptides and target epitopes with undesirable properties. Conclusions For small datasets (a few hundred proteins it is possible to solve the problem to optimality with moderate computational effort using commercial or free solvers. Larger datasets, like full proteomes require the use of heuristics.

Mapping of Lol p I allergenic epitopes by using murine monoclonal antibodies.

Science.gov (United States)

Mourad, W; Bernier, D; Jobin, M; Hébert, J

1989-11-01

Murine monoclonal antibodies (MAbs) against three non-overlapping epitopes of Lol p I allergen were previously produced and subsequently used for purification of the allergen. In the present study, these MAbs were further characterized, and the biological activity of the purified allergen assessed. The three MAbs were of the IgG isotype and carried a kappa light chain. Their affinity constants were in the range of 7.4-15.1 x 10(-9) mol/l. Purified Lol p I kept its biological activity, as shown by its ability to induce histamine release by basophils of Lol p I-sensitive patients. The profiles of histamine release induced by either Lol p I or crude Lolium perenne extracts were comparable. This observation suggests that human IgE bound to basophils are polyspecific which has been confirmed by immunoblot and inhibition assay. Our data indicated also that Lol p I possesses a major allergenic epitope recognized by all human serum IgE tested. This epitope seems to be partially shared by those recognized by the three MAbs. Finally, preincubation of Lol p I with either one of the Mabs did not affect significantly the basophil-histamine release induced by the purified allergen. This suggests that Lol p I possesses allergenic sites other than the one shared by MAbs and IgE Abs.

Limited naturally occurring escape in broadly neutralizing antibody epitopes in hepatitis C glycoprotein E2 and constrained sequence usage in acute infection

NARCIS (Netherlands)

Rodrigo, Chaturaka; Walker, Melanie R.; Leung, Preston; Eltahla, Auda A.; Grebely, Jason; Dore, Gregory J.; Applegate, Tanya; Page, Kimberly; Dwivedi, Sunita; Bruneau, Julie; Morris, Meghan D.; Cox, Andrea L.; Osburn, William; Kim, Arthur Y.; Schinkel, Janke; Shoukry, Naglaa H.; Lauer, Georg M.; Maher, Lisa; Hellard, Margaret; Prins, Maria; Luciani, Fabio; Lloyd, Andrew R.; Bull, Rowena A.

2017-01-01

Broadly neutralizing antibodies have been associated with spontaneous clearance of the hepatitis C infection as well as viral persistence by immune escape. Further study of neutralizing antibody epitopes is needed to unravel pathways of resistance to virus neutralization, and to identify conserved

Screening and identification of T helper 1 and linear immunodominant antibody-binding epitopes in spike 1 domain and membrane protein of feline infectious peritonitis virus.

Science.gov (United States)

Takano, Tomomi; Morioka, Hiroyuki; Gomi, Kohji; Tomizawa, Keisuke; Doki, Tomoyoshi; Hohdatsu, Tsutomu

2014-04-01

Feline infectious peritonitis virus (FIP virus: FIPV) causes a fatal disease in wild and domestic cats. The development of an FIP-preventive vaccine requires an antigen that does not induce antibody-dependent enhancement, and T helper (Th)1 activity plays an important role in protect against FIPV infection. In the present study, we identified synthetic peptides including Th1 and a linear immunodominant antibody-binding epitope in the S1 domain and M protein of FIPV. We also identified peptides that strongly induce Th1 activity from those derived from the structural proteins (S, M, and N proteins) of FIPV based on this and previous studies (Satoh et al. [19]). No Th1 epitope-containing peptide was identified in the peptides derived from the S1 domain of type I FIPV. In contrast, 7 Th1 epitope-containing peptides were identified in the S1 domain of type II FIPV, and no linear immunodominant antibody-binding epitope was contained in any of these peptides. Eleven Th1 epitope-containing peptides common to each serotype were identified in the M protein-derived peptides, and 2 peptides (M-11 and M-12) contained the linear immunodominant antibody-binding epitope. Of the peptides derived from the S, M, and N proteins of FIPV, those that induced significantly stronger Th1 activity than that of the FIPV antigen were rescreened, and 4 peptides were identified. When 3 of these peptides (M-9, I-S2-15, and II-S1-24) were selected and administered with CpG-ODNs to SPF cats, M-9 and II-S1-24 induced Th1 activity. Our results may provide important information for the development of a peptide-based vaccine against FIPV infection. Copyright © 2014 Elsevier Ltd. All rights reserved.

Identification of one B-cell epitope from NS1 protein of duck Tembusu virus with monoclonal antibodies.

Directory of Open Access Journals (Sweden)

Jinfeng Ti

Full Text Available This study describes the identification of one linear B-cell epitope on TMUV NS1 protein with monoclonal antibody (mAb 3G2 by indirect enzyme-linked immunosorbent assay (ELISA. In this study, NS1 protein was expressed in prokaryotic expression system and purified. One mAb against NS1 protein was generated from Balb/c mice immunized with recombinant protein NS1. A set of 35 partially-overlapping polypeptides covering the entire NS1 protein was expressed with PGEX-6P-1 vector and screened with mAb 3G2. One polypeptide against the mAb was acquired and identified by indirect ELISA and western-blot. To map the epitope accurately, one or two amino acid residues were removed from the carboxy and amino terminal of polypeptide sequentially. A series of truncated oligopeptides were expressed and purified. The minimal determinant of the linear B cell epitope was recognized and identified with mAb 3G2. The accurate linear B-cell epitope was 269DEKEIV274 located in NS1 protein. Furthermore, sequence alignment showed that the epitope was highly conserved and specific among TMUV strains and other flavivirus respectively. The linear B-cell epitope of TMUV NS1 protein could benefit the development of new vaccines and diagnostic assays.

Development of Broadly Neutralizing Antibody Mimitopes for Characterization of CRF01_AE HIV-1 Antibody Responses

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Jesse V. Schoen

2017-10-01

Full Text Available Mapping humoral immune responses to HIV-1 over the course of natural infection is important in understanding epitope exposure in relation to elicitation of broadly neutralizing antibodies (bNAbs, which is considered imperative for effective vaccine design. When analyzing HIV-specific immune responses, the antibody binding profiles may be a correlate for functional antibody activity. In this study, we utilized phage display technology to identify novel mimitopes that may represent Env epitope structures bound by bNAbs directed at V1V2 and V3 domains, CD4 binding site (CD4bs and the membrane proximal external region (MPER of Env. Mimitope sequence motifs were determined for each bNAb epitope. Given the ongoing vaccine development efforts in Thailand, these mimitopes that represent CD4bs and MPER epitopes were used to map immune responses of HIV-1 CRF01_AE-infected individuals with known neutralizing responses from two distinct time periods, 1996-98 and 2012-15. The more contemporary cohort showed an increase in binding breadth with binding observed for all MPER and CD4bs mimitopes, while the older cohort showed only 75% recognition of the CD4bs mimitopes and no MPER mimotope binding. Furthermore, mimitope binding profiles correlated significantly with magnitude (p=0.0036 and breadth (p=0.0358 of neutralization of a multi-subtype Tier 1 panel of pseudoviruses. These results highlight the utility of this mimitope mapping approach for detecting human plasma IgG-specificities that target known neutralizing antibody epitopes, and may also provide an indication of the plasticity of antibody binding within HIV-1 Env neutralization determinants.

Antibodies against Escherichia coli O24 and O56 O-Specific Polysaccharides Recognize Epitopes in Human Glandular Epithelium and Nervous Tissue

Science.gov (United States)

Korzeniowska-Kowal, Agnieszka; Kochman, Agata; Gamian, Elżbieta; Lis-Nawara, Anna; Lipiński, Tomasz; Seweryn, Ewa; Ziółkowski, Piotr; Gamian, Andrzej

2015-01-01

Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, contains the O-polysaccharide, which is important to classify bacteria into different O-serological types within species. The O-polysaccharides of serotypes O24 and O56 of E. coli contain sialic acid in their structures, already established in our previous studies. Here, we report the isolation of specific antibodies with affinity chromatography using immobilized lipopolysaccharides. Next, we evaluated the reactivity of anti-O24 and anti-O56 antibody on human tissues histologically. The study was conducted under the assumption that the sialic acid based molecular identity of bacterial and tissue structures provides not only an understanding of the mimicry-based bacterial pathogenicity. Cross-reacting antibodies could be used to recognize specific human tissues depending on their histogenesis and differentiation, which might be useful for diagnostic purposes. The results indicate that various human tissues are recognized by anti-O24 and anti-O56 antibodies. Interestingly, only a single specific reactivity could be found in the anti-O56 antibody preparation. Several tissues studied were not reactive with either antibody, thus proving that the presence of cross-reactive antigens was tissue specific. In general, O56 antibody performed better than O24 in staining epithelial and nervous tissues. Positive staining was observed for both normal (ganglia) and tumor tissue (ganglioneuroma). Epithelial tissue showed positive staining, but an epitope recognized by O56 antibody should be considered as a marker of glandular epithelium. The reason is that malignant glandular tumor and its metastasis are stained, and also epithelium of renal tubules and glandular structures of the thyroid gland are stained. Stratified epithelium such as that of skin is definitely not stained. Therefore, the most relevant observation is that the epitope recognized by anti-O56 antibodies is a new marker

DNA-mediated strand displacement facilitates sensitive electronic detection of antibodies in human serums.

Science.gov (United States)

Dou, Baoting; Yang, Jianmei; Shi, Kai; Yuan, Ruo; Xiang, Yun

2016-09-15

We describe here the development of a sensitive and convenient electronic sensor for the detection of antibodies in human serums. The sensor is constructed by self-assembly formation of a mixed monolayer containing the small molecule epitope conjugated double stranded DNA probes on gold electrode. The target antibody binds the epitope on the dsDNA probe and lowers the melting temperature of the duplex, which facilitates the displacement of the antibody-linked strand of the duplex probe by an invading methylene blue-tagged single stranded DNA (MB-ssDNA) through the strand displacement reaction and leads to the capture of many MB-ssDNA on the sensor surface. Subsequent electrochemical oxidation of the methylene blue labels results in amplified current response for sensitive monitoring of the antibodies. The antibody assay conditions are optimized and the sensor exhibits a linear range between 1.0 and 25.0nM with a detection limit of 0.67nM for the target antibody. The sensor is also selective and can be employed to detect the target antibodies in human serum samples. With the advantages of using small molecule epitope as the antibody recognition element over traditional antigen, the versatile manipulability of the DNA probes and the unique properties of the electrochemical transduction technique, the developed sensor thus hold great potential for simple and sensitive detection of different antibodies and other proteins in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Disease-specific monoclonal antibodies targeting glutamate decarboxylase impair GABAergic neurotransmission and affect motor learning and behavioral functions

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Mario U Manto

2015-03-01

Full Text Available Autoantibodies to the smaller isoform of glutamate decarboxylase can be found in patients with type 1 diabetes and a number of neurological disorders, including stiff-person syndrome, cerebellar ataxia and limbic encephalitis. The detection of disease-specific autoantibody epitopes led to the hypothesis that distinct glutamate decarboxylase autoantibodies may elicit specific neurological phenotypes. We explored the in vitro/in vivo effects of well-characterized monoclonal glutamate decarboxylase antibodies. We found that glutamate decarboxylase autoantibodies present in patients with stiff person syndrome (n = 7 and cerebellar ataxia (n = 15 recognized an epitope distinct from that recognized by glutamate decarboxylase autoantibodies present in patients with type 1 diabetes mellitus (n = 10 or limbic encephalitis (n = 4. We demonstrated that the administration of a monoclonal glutamate decarboxylase antibody representing this epitope specificity (1 disrupted in vitro the association of glutamate decarboxylase with γ-Aminobutyric acid containing synaptic vesicles, (2 depressed the inhibitory synaptic transmission in cerebellar slices with a gradual time course and a lasting suppressive effect, (3 significantly decreased conditioned eyelid responses evoked in mice, with no modification of learning curves in the classical eyeblink-conditioning task, (4 markedly impaired the facilitatory effect exerted by the premotor cortex over the motor cortex in a paired-pulse stimulation paradigm, and (5 induced decreased exploratory behavior and impaired locomotor function in rats. These findings support the specific targeting of glutamate decarboxylase by its autoantibodies in the pathogenesis of stiff-person syndrome and cerebellar ataxia. Therapies of these disorders based on selective removal of such glutamate decarboxylase antibodies could be envisioned.

Antibody response to a synthetic peptide covering a LAV-1/HTLV-IIIB neutralization epitope and disease progression

NARCIS (Netherlands)

Boucher, C. A.; de Wolf, F.; Houweling, J. T.; Bakker, M.; Dekker, J.; Roos, M. T.; Coutinho, R. A.; van der Noordaa, J.; Goudsmit, J.

1989-01-01

Sequential sera of homosexual men participating in a prospective study on the incidence of HIV-1 infection and risk factors for AIDS were tested for the presence of antibodies to a synthetic 17-mer (Neu21; KSIRIQRGPGRAFVTIG) representing a neutralization epitope as present on the LAV-1/HTLV-IIIB

Potential for novel MUC1 glycopeptide-specific antibody in passive cancer immunotherapy

DEFF Research Database (Denmark)

Madsen, Caroline B; Wandall, Hans H; Pedersen, Anders Elm

2013-01-01

MUC1 is an important target for antibodies in passive cancer immunotherapy. Antibodies against mucin glycans or mucin peptide backbone alone may give rise to cross reactivity with normal tissues. Therefore, attempts to identify antibodies against cancer-specific MUC1 glycopeptide epitopes havebeen...

Single-Domain Antibodies and the Promise of Modular Targeting in Cancer Imaging and Treatment

Directory of Open Access Journals (Sweden)

María Elena Iezzi

2018-02-01

Full Text Available Monoclonal antibodies and their fragments have significantly changed the outcome of cancer in the clinic, effectively inhibiting tumor cell proliferation, triggering antibody-dependent immune effector cell activation and complement mediated cell death. Along with a continued expansion in number, diversity, and complexity of validated tumor targets there is an increasing focus on engineering recombinant antibody fragments for lead development. Single-domain antibodies (sdAbs, in particular those engineered from the variable heavy-chain fragment (VHH gene found in Camelidae heavy-chain antibodies (or IgG2 and IgG3, are the smallest fragments that retain the full antigen-binding capacity of the antibody with advantageous properties as drugs. For similar reasons, growing attention is being paid to the yet smaller variable heavy chain new antigen receptor (VNAR fragments found in Squalidae. sdAbs have been selected, mostly from immune VHH libraries, to inhibit or modulate enzyme activity, bind soluble factors, internalize cell membrane receptors, or block cytoplasmic targets. This succinct review is a compilation of recent data documenting the application of engineered, recombinant sdAb in the clinic as epitope recognition “modules” to build monomeric, dimeric and multimeric ligands that target, tag and stall solid tumor growth in vivo. Size, affinity, specificity, and the development profile of sdAbs drugs are seemingly consistent with desirable clinical efficacy and safety requirements. But the hepatotoxicity of the tetrameric anti-DR5-VHH drug in patients with pre-existing anti-drug antibodies halted the phase I clinical trial and called for a thorough pre-screening of the immune and poly-specific reactivities of the sdAb leads.

Elucidation of the critical epitope of an anti-EGFR monoclonal antibody EMab-134.

Science.gov (United States)

Kaneko, Mika K; Yamada, Shinji; Itai, Shunsuke; Chang, Yao-Wen; Nakamura, Takuro; Yanaka, Miyuki; Kato, Yukinari

2018-07-01

The epidermal growth factor receptor (EGFR) is a type-1 transmembrane receptor tyrosine kinase, which activates the downstream signaling cascades in many tumors, such as oral and lung cancers. We previously developed EMab-134, a novel anti-EGFR monoclonal antibody (mAb), which reacts with endogenous EGFR-expressing cancer cell lines and normal cells independent of glycosylation in Western blotting, flow cytometry, and immunohistochemical analysis. EMab-134 showed very high sensitivity (94.7%) to oral squamous cell carcinomas in immunohistochemical analysis. In this study, we performed enzyme-linked immunosorbent assay (ELISA), flow cytometry, and immunohistochemical analysis to determine the epitope of EMab-134. A blocking peptide (375-394 amino acids of EGFR) neutralized the EMab-134 reaction against oral cancer cells in flow cytometry and immunohistochemistry. The minimum epitope of EMab-134 was found to be the 377- RGDSFTHTPP -386 sequence. Our findings can be applied for the production of more functional anti-EGFR mAbs that in turn can be used for antitumor treatments.

Production of mouse monoclonal antibody against Streptococcus dysgalactiae GapC protein and mapping its conserved B-cell epitope.

Science.gov (United States)

Zhang, Limeng; Zhang, Hua; Fan, Ziyao; Zhou, Xue; Yu, Liquan; Sun, Hunan; Wu, Zhijun; Yu, Yongzhong; Song, Baifen; Ma, Jinzhu; Tong, Chunyu; Zhu, Zhanbo; Cui, Yudong

2015-02-01

Streptococcus dysgalactiae (S. dysgalactiae) GapC protein is a protective antigen that induces partial immunity against S. dysgalactiae infection in animals. To identify the conserved B-cell epitope of S. dysgalactiae GapC, a mouse monoclonal antibody 1E11 (mAb1E11) against GapC was generated and used to screen a phage-displayed 12-mer random peptide library (Ph.D.-12). Eleven positive clones recognized by mAb1E11 were identified, most of which matched the consensus motif TGFFAKK. Sequence of the motif exactly matched amino acids 97-103 of the S. dysgalactiae GapC. In addition, the epitope (97)TGFFAKK(103) showed high homology among different streptococcus species. Site-directed mutagenic analysis further confirmed that residues G98, F99, F100 and K103 formed the core of (97)TGFFAKK(103), and this core motif was the minimal determinant of the B-cell epitope recognized by the mAb1E11. Collectively, the identification of conserved B-cell epitope within S. dysgalactiae GapC highlights the possibility of developing the epitope-based vaccine. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mature Epitope Density - A strategy for target selection based on immunoinformatics and exported prokaryotic proteins

DEFF Research Database (Denmark)

Santos, Anderson R; Pereira, Vanessa Bastos; Barbosa, Eudes

2013-01-01

. However, currently available tools do not account for the concentration of epitope products in the mature protein product and its relation to the reliability of target selection. RESULTS: We developed a computational strategy based on measuring the epitope's concentration in the mature protein, called...... Mature Epitope Density (MED). Our method, though simple, is capable of identifying promising vaccine targets. Our online software implementation provides a computationally light and reliable analysis of bacterial exoproteins and their potential for vaccines or diagnosis projects against pathogenic...... proteins were confirmed as related. There was no experimental evidence of antigenic or pathogenic contributions for three of the highest MED-scored Mtb proteins. Hence, these three proteins could represent novel putative vaccine and drug targets for Mtb. A web version of MED is publicly available online...

Immune Epitope Database and Analysis Resource (IEDB)

Data.gov (United States)

U.S. Department of Health & Human Services — This repository contains antibody/B cell and T cell epitope information and epitope prediction and analysis tools for use by the research community worldwide. Immune...

Plasticity and Epitope Exposure of the HIV-1 Envelope Trimer.

Science.gov (United States)

Powell, Rebecca L R; Totrov, Maxim; Itri, Vincenza; Liu, Xiaomei; Fox, Alisa; Zolla-Pazner, Susan

2017-09-01

We recently showed that mutations in the HIV-1 envelope (Env) destabilize the V3 loop, rendering neutralization-resistant viruses sensitive to V3-directed monoclonal antibodies (MAbs). Here, we investigated the propagation of this effect on other Env epitopes, with special emphasis on V2 loop exposure. Wild-type JR-FL and 19 mutant JR-FL pseudoviruses were tested for neutralization sensitivity to 21 MAbs specific for epitopes in V2, the CD4 binding site (CD4bs), and the CD4-induced (CD4i) region. Certain glycan mutants, mutations in the gp120 hydrophobic core, and mutations in residues involved in intraprotomer interactions exposed epitopes in the V2i region (which overlies the α4β7 integrin binding site) and the V3 crown, suggesting general destabilization of the distal region of the trimer apex. In contrast, other glycan mutants, mutations affecting interprotomer interactions, and mutations affecting the CD4bs exposed V3 but not V2i epitopes. These data indicate for the first time that V3 can move independently of V2, with V3 pivoting out from its "tucked" position in the trimer while apparently leaving the V2 apex intact. Notably, none of the mutations exposed V2 epitopes without also exposing V3, suggesting that movement of V2 releases V3. Most mutations increased sensitivity to CD4bs-directed MAbs without exposure of the CD4i epitope, implying these mutations facilitate the trimers' maintenance of an intermediate energy state between open and closed conformations. Taken together, these data indicate that several transient Env epitopes can be rendered more accessible to antibodies (Abs) via specific mutations, and this may facilitate the design of V1V2-targeting immunogens. IMPORTANCE Many epitopes of the HIV envelope (Env) spike are relatively inaccessible to antibodies (Abs) compared to their exposure in the open Env conformation induced by receptor binding. However, the reduced infection rate that resulted from the vaccine used in the RV144 HIV-1 vaccine

Identification and fine mapping of a linear B cell epitope of human vimentin

DEFF Research Database (Denmark)

Dam, Catharina Essendrup; Houen, Gunnar; Hansen, Paul R.

2014-01-01

Knowledge about antibody-antigen interactions is important for the understanding of the immune system mechanisms and for supporting development of drugs and biomarkers. A tool for identification of these antigenic epitopes of specific antibodies is epitope mapping. In this study, a modified enzyme......-linked immunosorbent assay was applied for epitope mapping of a mouse monoclonal vimentin antibody using overlapping resin-bound peptides covering the entire vimentin protein. The minimal epitope required for binding was identified as the LDSLPLVD sequence using N- and C-terminally truncated peptides. The peptide...... sequence LDSLPLVDTH was identified as the complete epitope, corresponding to amino acids 428-437 in the C-terminal end of the human vimentin protein. Alanine scanning and functionality scanning applying substituted peptides were used to identify amino acids essential for antibody reactivity. In particular...

Human monoclonal antibodies to a novel cluster of conformational epitopes on HCV E2 with resistance to neutralization escape in a genotype 2a isolate

DEFF Research Database (Denmark)

Keck, Zhen-yong; Xia, Jinming; Wang, Yong

2012-01-01

The majority of broadly neutralizing antibodies to hepatitis C virus (HCV) are against conformational epitopes on the E2 glycoprotein. Many of them recognize overlapping epitopes in a cluster, designated as antigenic domain B, that contains residues G530 and D535. To gain information on other reg...

Epitope-based peptide vaccine design and target site depiction against Ebola viruses: an immunoinformatics study.

Science.gov (United States)

Khan, M A; Hossain, M U; Rakib-Uz-Zaman, S M; Morshed, M N

2015-07-01

Ebola viruses (EBOVs) have been identified as an emerging threat in recent year as it causes severe haemorrhagic fever in human. Epitope-based vaccine design for EBOVs remains a top priority because a mere progress has been made in this regard. Another reason is the lack of antiviral drug and licensed vaccine although there is a severe outbreak in Central Africa. In this study, we aimed to design an epitope-based vaccine that can trigger a significant immune response as well as to prognosticate inhibitor that can bind with potential drug target sites using various immunoinformatics and docking simulation tools. The capacity to induce both humoral and cell-mediated immunity by T cell and B cell was checked for the selected protein. The peptide region spanning 9 amino acids from 42 to 50 and the sequence TLASIGTAF were found as the most potential B and T cell epitopes, respectively. This peptide could interact with 12 HLAs and showed high population coverage up to 80.99%. Using molecular docking, the epitope was further appraised for binding against HLA molecules to verify the binding cleft interaction. In addition with this, the allergenicity of the epitopes was also evaluated. In the post-therapeutic strategy, docking study of predicted 3D structure identified suitable therapeutic inhibitor against targeted protein. However, this computational epitope-based peptide vaccine designing and target site prediction against EBOVs open up a new horizon which may be the prospective way in Ebola viruses research; the results require validation by in vitro and in vivo experiments. © 2015 John Wiley & Sons Ltd.

Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers

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Rasool Suhail

2007-09-01

Full Text Available Abstract Background Amyloid-related degenerative diseases are associated with the accumulation of misfolded proteins as amyloid fibrils in tissue. In Alzheimer disease (AD, amyloid accumulates in several distinct types of insoluble plaque deposits, intracellular Aβ and as soluble oligomers and the relationships between these deposits and their pathological significance remains unclear. Conformation dependent antibodies have been reported that specifically recognize distinct assembly states of amyloids, including prefibrillar oligomers and fibrils. Results We immunized rabbits with a morphologically homogeneous population of Aβ42 fibrils. The resulting immune serum (OC specifically recognizes fibrils, but not random coil monomer or prefibrillar oligomers, indicating fibrils display a distinct conformation dependent epitope that is absent in prefibrillar oligomers. The fibril epitope is also displayed by fibrils of other types of amyloids, indicating that the epitope is a generic feature of the polypeptide backbone. The fibril specific antibody also recognizes 100,000 × G soluble fibrillar oligomers ranging in size from dimer to greater than 250 kDa on western blots. The fibrillar oligomers recognized by OC are immunologically distinct from prefibrillar oligomers recognized by A11, even though their sizes overlap broadly, indicating that size is not a reliable indicator of oligomer conformation. The immune response to prefibrillar oligomers and fibrils is not sequence specific and antisera of the same specificity are produced in response to immunization with islet amyloid polypeptide prefibrillar oligomer mimics and fibrils. The fibril specific antibodies stain all types of amyloid deposits in human AD brain. Diffuse amyloid deposits stain intensely with anti-fibril antibody although they are thioflavin S negative, suggesting that they are indeed fibrillar in conformation. OC also stains islet amyloid deposits in transgenic mouse models of type

Epitopes in α8β1 and other RGD-binding integrins delineate classes of integrin-blocking antibodies and major binding loops in α subunits

OpenAIRE

Norihisa Nishimichi; Nagako Kawashima; Yasuyuki Yokosaki

2015-01-01

Identification of epitopes for integrin-blocking monoclonal antibodies (mAbs) has aided our understanding of structure-function relationship of integrins. We mapped epitopes of chicken anti-integrin-α8-subunit-blocking mAbs by mutational analyses, examining regions that harboured all mapped epitopes recognized by mAbs against other α-subunits in the RGD-binding-integrin subfamily. Six mAbs exhibited blocking function, and these mAbs recognized residues on the same W2:41-loop on the top-face o...

Construction, expression, purification and biotin labeling of a single recombinant multi-epitope antigen for double-antigen sandwich ELISA to detect hepatitis C virus antibody.

Science.gov (United States)

He, Jing; Xiu, Bingshui; Wang, Guohua; Chen, Kun; Feng, Xiaoyan; Song, Xiaoguo; Zhu, Cuixia; Yang, Xiqin; Bai, Guanzhong; Ling, Shigan; Zhang, Heqiu

2011-08-01

Based on B cell epitope predictions, a recombinant antigen with multiple epitopes from four Hepatitis C Virus fragments (C, NS3, NS4 and NS5) were engineered. The recombinant gene was then highly expressed in E. coli. The non-modified and C-terminal-modified recombinant proteins were used for coating and biotin labeling, respectively, to establish the double-antigen sandwich ELISA. Ten positive reference samples confirmed by the CHIRON RIBA HCV 3.0 SIA kit were detected positive, Forty one plasma samples were positive among samples from 441 volunteers, which indicated that the recombinant antigen could readily react well with plasma HCV antibody. As critical reagents of double-antigen sandwich ELISA, the recombinant multi-epitope antigen and the C-terminal-modified and biotin-conjugated antigen show good antigenicity. In this study, we provide a simple approach to produce multiple epitopes within one recombinant protein in order to avoid the costly expression of less-effective pools of multiple proteins, which is the conventional strategy of diagnostic antigen production for HCV antibody detection.

Epitope targeting of tertiary protein structure enables target-guided synthesis of a potent in-cell inhibitor of botulinum neurotoxin.

Science.gov (United States)

Farrow, Blake; Wong, Michelle; Malette, Jacquie; Lai, Bert; Deyle, Kaycie M; Das, Samir; Nag, Arundhati; Agnew, Heather D; Heath, James R

2015-06-08

Botulinum neurotoxin (BoNT) serotype A is the most lethal known toxin and has an occluded structure, which prevents direct inhibition of its active site before it enters the cytosol. Target-guided synthesis by in situ click chemistry is combined with synthetic epitope targeting to exploit the tertiary structure of the BoNT protein as a landscape for assembling a competitive inhibitor. A substrate-mimicking peptide macrocycle is used as a direct inhibitor of BoNT. An epitope-targeting in situ click screen is utilized to identify a second peptide macrocycle ligand that binds to an epitope that, in the folded BoNT structure, is active-site-adjacent. A second in situ click screen identifies a molecular bridge between the two macrocycles. The resulting divalent inhibitor exhibits an in vitro inhibition constant of 165 pM against the BoNT/A catalytic chain. The inhibitor is carried into cells by the intact holotoxin, and demonstrates protection and rescue of BoNT intoxication in a human neuron model. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Epitope and functional specificity of monoclonal antibodies to mouse gamma interferon: the synthetic peptide approach

International Nuclear Information System (INIS)

Russell, J.K.; Hayes, M.P.; Carter, J.M.; Torres, B.A.; Dunn, B.M.; Johnson, H.M.

1986-01-01

Four anti-recombinant mouse gamma interferon (α-IFNγ) monoclonal antibodies were generated using hamster spleen cells. Binding of 125 I-IFNγ by these protein A-bound antibodies was specifically blocked by cold IFNγ. Binding by three of these antibodies was also blocked by a synthetic peptide corresponding to the N-terminal 1-39 amino acids of IFNγ, while a corresponding C-terminal (95-133) peptide had no effect on binding. One of the N-terminal specific monoclonal antibodies inhibited both the antiviral and macrophage priming (for tumor cell killing) activities of IFNγ, while the other two had no effect on either biological function. Blocking experiments with cold IFNγ and N-terminal peptide suggest that the epitope specificities of the monoclonal antibodies could be determined by the conformational or topographic structure of IFNγ. Polyclonal antibodies to either the N-terminal or C-terminal peptides also inhibited both the antiviral and macrophage priming activities of IFNγ. All of the antibodies that inhibited IFNγ function also blocked binding of IFNγ to membrane receptor on cells, while antibodies that did not inhibit function also did not block binding. The data suggest that both the N-terminal and C-terminal domains of IFNγ play an important role in its antiviral and macrophage priming functions, possibly in a cooperative manner

Induction of antibodies against epitopes inaccessible on the HIV type 1 envelope oligomer by immunization with recombinant monomeric glycoprotein 120

DEFF Research Database (Denmark)

Schønning, Kristian; Bolmstedt, A; Novotny, J

1998-01-01

An N-glycan (N306) at the base of the V3 loop of HIV-BRU gp120 is shielding a linear neutralization epitope at the tip of the V3 loop on oligomeric Env. In contrast, this epitope is readily antigenic on monomeric gp120. Immunization with recombinant monomeric HIV-BRU gp120 may thus be expected...... immunogenic structures inaccessible on the envelope oligomer. The limited ability of recombinant gp120 vaccines to induce neutralizing antibodies against primary isolates may thus not exclusively reflect genetic variation....

Structure of an N276-Dependent HIV-1 Neutralizing Antibody Targeting a Rare V5 Glycan Hole Adjacent to the CD4 Binding Site

Energy Technology Data Exchange (ETDEWEB)

Wibmer, Constantinos Kurt; Gorman, Jason; Anthony, Colin S.; Mkhize, Nonhlanhla N.; Druz, Aliaksandr; York, Talita; Schmidt, Stephen D.; Labuschagne, Phillip; Louder, Mark K.; Bailer, Robert T.; Karim, Salim S. Abdool; Mascola, John R.; Williamson, Carolyn; Moore, Penny L.; Kwong, Peter D.; Morris, Lynn (NHLS-South Africa); (NIH); (Witwatersrand); (KwaZulu-Natal)

2016-08-31

All HIV-1-infected individuals develop strain-specific neutralizing antibodies to their infecting virus, which in some cases mature into broadly neutralizing antibodies. Defining the epitopes of strain-specific antibodies that overlap conserved sites of vulnerability might provide mechanistic insights into how broadly neutralizing antibodies arise. We previously described an HIV-1 clade C-infected donor, CAP257, who developed broadly neutralizing plasma antibodies targeting an N276 glycan-dependent epitope in the CD4 binding site. The initial CD4 binding site response potently neutralized the heterologous tier 2 clade B viral strain RHPA, which was used to design resurfaced gp120 antigens for single-B-cell sorting. Here we report the isolation and structural characterization of CAP257-RH1, an N276 glycan-dependent CD4 binding site antibody representative of the early CD4 binding site plasma response in donor CAP257. The cocrystal structure of CAP257-RH1 bound to RHPA gp120 revealed critical interactions with the N276 glycan, loop D, and V5, but not with aspartic acid 368, similarly to HJ16 and 179NC75. The CAP257-RH1 monoclonal antibody was derived from the immunoglobulin-variable IGHV3-33 and IGLV3-10 genes and neutralized RHPA but not the transmitted/founder virus from donor CAP257. Its narrow neutralization breadth was attributed to a binding angle that was incompatible with glycosylated V5 loops present in almost all HIV-1 strains, including the CAP257 transmitted/founder virus. Deep sequencing of autologous CAP257 viruses, however, revealed minority variants early in infection that lacked V5 glycans. These glycan-free V5 loops are unusual holes in the glycan shield that may have been necessary for initiating this N276 glycan-dependent CD4 binding site B-cell lineage.

IMPORTANCEThe conserved CD4 binding site on gp120 is a major target for HIV-1 vaccine design, but key events in the elicitation and maturation of

Monoclonal antibodies based on hybridoma technology.

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Yagami, Hisanori; Kato, Hiroshi; Tsumoto, Kanta; Tomita, Masahiro

2013-03-01

Based on the size and scope of the present global market for medicine, monoclonal antibodies (mAbs) have a very promising future, with applications for cancers through autoimmune ailments to infectious disease. Since mAbs recognize only their target antigens and not other unrelated proteins, pinpoint medical treatment is possible. Global demand is dramatically expanding. Hybridoma technology, which allows production of mAbs directed against antigens of interest is therefore privileged. However, there are some pivotal points for further development to generate therapeutic antibodies. One is selective generation of human mAbs. Employment of transgenic mice producing human antibodies would overcome this problem. Another focus is recognition sites and conformational epitopes in antigens may be just as important as linear epitopes, especially when membrane proteins such as receptors are targeted. Recognition of intact structures is of critical importance for medical purposes. In this review, we describe patent related information for therapeutic mAbs based on hybridoma technology and also discuss new advances in hybridoma technology that facilitate selective production of stereospecific mAbs.

Elucidation of the critical epitope of an anti-EGFR monoclonal antibody EMab-134

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Mika K. Kaneko

2018-07-01

Full Text Available The epidermal growth factor receptor (EGFR is a type-1 transmembrane receptor tyrosine kinase, which activates the downstream signaling cascades in many tumors, such as oral and lung cancers. We previously developed EMab-134, a novel anti-EGFR monoclonal antibody (mAb, which reacts with endogenous EGFR-expressing cancer cell lines and normal cells independent of glycosylation in Western blotting, flow cytometry, and immunohistochemical analysis. EMab-134 showed very high sensitivity (94.7% to oral squamous cell carcinomas in immunohistochemical analysis. In this study, we performed enzyme-linked immunosorbent assay (ELISA, flow cytometry, and immunohistochemical analysis to determine the epitope of EMab-134. A blocking peptide (375–394 amino acids of EGFR neutralized the EMab-134 reaction against oral cancer cells in flow cytometry and immunohistochemistry. The minimum epitope of EMab-134 was found to be the 377-RGDSFTHTPP−386 sequence. Our findings can be applied for the production of more functional anti-EGFR mAbs that in turn can be used for antitumor treatments.

Monoclonal antibody therapy of inflammatory bowel disease

NARCIS (Netherlands)

van Deventer, S. J.; Camoglio, L.

1996-01-01

Several anti-inflammatory drugs have therapeutic efficacy in inflammatory bowel disease, but their targets remain incompletely characterized. The development of monoclonal antibodies that either recognize epitopes on immune-competent cells, or neutralize pro-inflammatory cytokines, has helped to

Endoplasmic reticulum targeting sequence enhances HBV-specific cytotoxic T lymphocytes induced by a CTL epitope-based DNA vaccine

International Nuclear Information System (INIS)

Xu Wei; Chu Yiwei; Zhang Ruihua; Xu Huanbin; Wang Ying; Xiong Sidong

2005-01-01

CD8 + T cells play a critical role in protective immunity against Hepatitis B Virus (HBV). Epitope-based DNA vaccines expressing HBV-dominant CTL epitopes can be used as candidate vaccines capable of inducing cytotoxic T Lymphocytes (CTL) responses. A plasmid DNA encoding a CTL epitope of HBV core antigen, HBc 18-27 , was constructed. Intramuscular immunization of C57BL/6 mice with this DNA vaccine resulted in successful induction of HBV-specific CTL responses. In order to promote transportation of the peptide into endoplasmic reticulum (ER) to bind to MHC class I molecules for optimal class I antigen presentation, an ER targeting sequence (ERTS) was fused with the C 18-27 encoding gene. ERTS fusion significantly enhanced specific CD8 + T cell responses in terms of CTL cytolysis as well as IFN-γ secretion. This enhancement was correlated with promoted epitope presentation on target cell surface. We report here an enhanced immunogenicity of an epitope-based DNA vaccine using an ER targeting signal sequence, which has significant implications for future design of therapeutic HBV vaccine

Epitope characterization of the ADA response directed against a targeted immunocytokine.

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Stubenrauch, Kay; Künzel, Christian; Vogel, Rudolf; Tuerck, Dietrich; Schick, Eginhard; Heinrich, Julia

2015-10-10

Targeted immunocytokines (TICs) display potent activity in selective tumor suppression. This class of multi domain biotherapeutics (MDBs) is composed of the three major domains Fab, Fc, and a cytokine which may induce a complex polyclonal anti-drug antibody (ADA) response. However, classical ADA assays usually are not suitable to specify ADAs and to identify the immunogenic domains of a TIC. The purpose of the present study was to establish epitope characterization of ADA responses in order to specify immunogenic responses against a TIC and their direct impact on the pharmacokinetic profile, safety, and efficacy. Based on standard ADA screening and confirmation assays, respectively, domain detection assays (DDAs) and domain competition assays (DCAs) were established and compared by the use of 12 ADA-positive samples obtained from a cynomolgus monkey study in early development. Both domain-specific assays were sensitive enough to preserve the positive screening assay result and revealed an overall accordance for the evaluation of domain-specific ADA responses. About half of the samples displayed one ADA specificity, either for the Fab or for the cytokine (Cy) domain, and the remaining samples showed a combination of Fab-specific and Cy-specific ADA fractions. Fc-specific ADAs occurred in only one sample. In-depth comparison of DCAs and DDAs showed that both assays appeared to be appropriate to assess multi-specific ADA responses as well as minor ADA fractions. An advantage of DCAs is typically a fast and easy assay establishment, whereas, DDAs in some cases may be superior to assess low abundant ADAs in multi-specific responses. Our results reveal that both approaches benefit from thorough reagent development as an essential precondition for reliable epitope characterization of ADA responses. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel antibody-dependent cellular cytotoxicity epitope in gp120 is identified by two monoclonal antibodies isolated from a long-term survivor of human immunodeficiency virus type 1 infection.

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Alsmadi, O; Herz, R; Murphy, E; Pinter, A; Tilley, S A

1997-01-01

Two monoclonal antibodies (MAbs), 42F and 43F, were isolated some 14 months apart from a single long-term survivor of human immunodeficiency virus type 1 (HIV-1) infection. These MAbs were found to be indistinguishable in terms of their isotypes, specificities, affinities, and biological activities. Both 42F and 43F directed substantial antibody-dependent cellular cytotoxicity (ADCC) against cells infected with four divergent lab-adapted strains of HIV-1, but no neutralizing activity against these strains was detectable. The ability of MAbs 42F and 43F, as well as that of MAbs against two other gp120 epitopes, to direct ADCC against uninfected CD4+ cells to which recombinant gp120SF2 had been adsorbed (i.e., "innocent bystanders") was demonstrated to be less efficient by at least an order of magnitude than their ability to direct ADCC against HIV-1-infected cells. Flow cytometry analyses showed that 42F and 43F also bind to native primary isolate Envs from clades B and E expressed on cell surfaces. By direct binding and competition assays, it was demonstrated that the 42F/43F epitope lies in a domain of gp120 outside the previously described CD4-binding site and V3 loop ADCC epitope clusters. Immunoblot analysis revealed that the 42F/43F epitope is not dependent on disulfide bonds or N-linked glycans in gp120. Epitope mapping of 42F and 43F by binding to linear peptides demonstrated specificity of these MAbs for a sequence of 10 amino acids in the C5 domain comprising residues 491 to 500 (Los Alamos National Laboratory numbering for the HXB2 strain). Thus, 42F and 43F define a new ADCC epitope in gp120. Because of the relative conservation of this epitope and the fact that it appears to have been significantly immunogenic in the individual from which these MAbs were derived, it may prove to be a useful component of HIV vaccines. Furthermore, these MAbs may be used as tools to probe the potential importance of ADCC as an antiviral activity in HIV-1 infection. PMID

Identification of a novel linear B-cell epitope using a monoclonal antibody against the carboxy terminus of the canine distemper virus nucleoprotein and sequence analysis of the identified epitope in different CDV isolates.

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Yi, Li; Cao, Zhigang; Tong, Mingwei; Cheng, Yuening; Yang, Yong; Li, Shuang; Wang, Jianke; Lin, Peng; Sun, Yaru; Zhang, Miao; Cheng, Shipeng

2017-09-29

The Nucleoprotein (NP) is the most abundant and highly immunogenic protein in canine distemper virus (CDV), playing an important role in CDV viral replication and assembly. In this study, a specific monoclonal antibody, named C8, was produced against the NP protein C terminal (amino acids 401-523). A linear N protein epitope was identified by subjecting a series of partially overlapping synthesized peptides to enzyme-linked immunosorbent assay (ELISA) analysis.The results indicated that 444 GDKYPIHFNDER 455 was the minimal linear epitope that could be recognized by mAb C8. Sequence alignments demonstrated that this linear epitope is less conserved among three CDV genotypes. We next analyzed the level of conservation of the defined epitope in19 Chinese CDV clinical isolates, and it has one site variation in amino acid among these CDV isolations. 2 isolates have the amino acid mutations F451L, while one has P448Ssubstitution.Phylogenetic analysis showed the two isolates with F451Lsubstitution had a closer relationship in a virulent strain ZJ-7, so the epitope may be a significant tag associated with virus virulence. This collection of mAb along with defined linear epitope may provide useful reagents for investigations of NP protein function and the development of CDV specific diagnostics.

Human antibodies to the dengue virus E-dimer epitope have therapeutic activity against Zika virus infection.

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Fernandez, Estefania; Dejnirattisai, Wanwisa; Cao, Bin; Scheaffer, Suzanne M; Supasa, Piyada; Wongwiwat, Wiyada; Esakky, Prabagaran; Drury, Andrea; Mongkolsapaya, Juthathip; Moley, Kelle H; Mysorekar, Indira U; Screaton, Gavin R; Diamond, Michael S

2017-11-01

The Zika virus (ZIKV) epidemic has resulted in congenital abnormalities in fetuses and neonates. Although some cross-reactive dengue virus (DENV)-specific antibodies can enhance ZIKV infection in mice, those recognizing the DENV E-dimer epitope (EDE) can neutralize ZIKV infection in cell culture. We evaluated the therapeutic activity of human monoclonal antibodies to DENV EDE for their ability to control ZIKV infection in the brains, testes, placentas, and fetuses of mice. A single dose of the EDE1-B10 antibody given 3 d after ZIKV infection protected against lethality, reduced ZIKV levels in brains and testes, and preserved sperm counts. In pregnant mice, wild-type or engineered LALA variants of EDE1-B10, which cannot engage Fcg receptors, diminished ZIKV burden in maternal and fetal tissues, and protected against fetal demise. Because neutralizing antibodies to EDE have therapeutic potential against ZIKV, in addition to their established inhibitory effects against DENV, it may be possible to develop therapies that control disease caused by both viruses.

Use of epitope libraries to identify exon-specific monoclonal antibodies for characterization of altered dystrophins in muscular dystrophy

Energy Technology Data Exchange (ETDEWEB)

Nguyen thi Man; Morris, G.E. (North East Wales Inst., Clwyd (United Kingdom))

1993-06-01

The majority of mutations in Xp21-linked muscular dystrophy (MD) can be identified by PCR or Southern blotting, as deletions or duplications of groups of exons in the dystrophin gene, but it is not always possible to predict how much altered dystrophin, if any, will be produced. Use of exon-specific monoclonal antibodies (mAbs) on muscle biopsies from MD patients can, in principle, provide information on both the amount of altered dystrophin produced and, when dystrophin is present, the nature of the genetic deletion or point mutation. For this purpose, mAbs which recognize regions of dystrophin encoded by known exons and whose binding is unaffected by the absence of adjacent exons are required. To map mAbs to specific exons, random [open quotes]libraries[close quotes] of expressed dystrophin fragments were created by cloning DNAseI digestion fragments of a 4.3-kb dystrophin cDNA into a pTEX expression vector. The libraries were then used to locate the epitopes recognized by 48 mAbs to fragments of 25--60 amino acids within the 1,434-amino-acid dystrophin fragment used to produce the antibodies. This is sufficiently detailed to allow further refinement by using synthetic peptides and, in many cases, to identify the exon in the DMD (Duchenne MD) gene which encodes the epitope. To illustrate their use in dystrophin analysis, a Duchenne patient with a frameshift deletion of exons 42 and 43 makes a truncated dystrophin encoded by exons 1--41, and the authors now show that this can be detected in the sarcolemma by mAbs up to and including those specific for exon 41 epitopes but not by mAbs specific for exon 43 or later epitopes. 38 refs., 2 figs., 4 tabs.

Intracellular and non-neuronal targets of voltage-gated potassium channel complex antibodies.

Science.gov (United States)

Lang, Bethan; Makuch, Mateusz; Moloney, Teresa; Dettmann, Inga; Mindorf, Swantje; Probst, Christian; Stoecker, Winfried; Buckley, Camilla; Newton, Charles R; Leite, M Isabel; Maddison, Paul; Komorowski, Lars; Adcock, Jane; Vincent, Angela; Waters, Patrick; Irani, Sarosh R

2017-04-01

Autoantibodies against the extracellular domains of the voltage-gated potassium channel (VGKC) complex proteins, leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-2 (CASPR2), are found in patients with limbic encephalitis, faciobrachial dystonic seizures, Morvan's syndrome and neuromyotonia. However, in routine testing, VGKC complex antibodies without LGI1 or CASPR2 reactivities (double-negative) are more common than LGI1 or CASPR2 specificities. Therefore, the target(s) and clinical associations of double-negative antibodies need to be determined. Sera (n=1131) from several clinically defined cohorts were tested for IgG radioimmunoprecipitation of radioiodinated α-dendrotoxin ( 125 I-αDTX)-labelled VGKC complexes from mammalian brain extracts. Positive samples were systematically tested for live hippocampal neuron reactivity, IgG precipitation of 125 I-αDTX and 125 I-αDTX-labelled Kv1 subunits, and by cell-based assays which expressed Kv1 subunits, LGI1 and CASPR2. VGKC complex antibodies were found in 162 of 1131 (14%) sera. 90 of these (56%) had antibodies targeting the extracellular domains of LGI1 or CASPR2. Of the remaining 72 double-negative sera, 10 (14%) immunoprecipitated 125 I-αDTX itself, and 27 (38%) bound to solubilised co-expressed Kv1.1/1.2/1.6 subunits and/or Kv1.2 subunits alone, at levels proportionate to VGKC complex antibody levels (r=0.57, p=0.0017). The sera with LGI1 and CASPR2 antibodies immunoprecipitated neither preparation. None of the 27 Kv1-precipitating samples bound live hippocampal neurons or Kv1 extracellular domains, but 16 (59%) bound to permeabilised Kv1-expressing human embryonic kidney 293T cells. These intracellular Kv1 antibodies mainly associated with non-immune disease aetiologies, poor longitudinal clinical-serological correlations and a limited immunotherapy response. Double-negative VGKC complex antibodies are often directed against cytosolic epitopes of Kv1 subunits and occasionally against

Epitope structure and binding affinity of single chain llama anti-β-amyloid antibodies revealed by proteolytic excision affinity-mass spectrometry.

Science.gov (United States)

Paraschiv, Gabriela; Vincke, Cécile; Czaplewska, Paulina; Manea, Marilena; Muyldermans, Serge; Przybylski, Michael

2013-01-01

ß-Amyloid (Aß) immunotherapy has become a promising strategy for reducing the level of Aß in brain. New immunological approaches have been recently proposed for rapid, early diagnosis, and molecular treatment of neurodegenerative diseases related to Alzheimer's Disease (AD). The combination of proteolytic epitope excision and extraction and mass spectrometry using digestion with various proteases has been shown to be an efficient tool for the identification and molecular characterization of antigenic determinants. Here, we report the identification of the Aβ epitope recognized by the variable domain of single chain llama anti-Aβ-antibodies, termed Aβ-nanobodies, that have been discovered in the blood of camelids and found to be promising candidates for immunotherapy of AD. The epitope recognized by two Aβ-specific nanobodies was identified by proteolytic epitope extraction- and excision-mass spectrometry using a series of proteases (trypsin, chymotrypsin, GluC-protease, and LysC-protease). Matrix-assisted laser desorption ionization--mass spectrometric analysis of the affinity--elution fraction provided the epitope, Aβ(17-28), in the mid- to carboxy-terminal domain of Aβ, which has been shown to exert an Aß-fibril inhibiting effect. Affinity studies of the synthetic epitope confirmed that the Aβ(17-28) peptide is the minimal fragment that binds to the nanobodies. The interactions between the nanobodies and full length Aβ(1-40) or Aβ-peptides containing or lacking the epitope sequence were further characterized by enzyme linked immunosorbent assay and bioaffinity analysis. Determinations of binding affinities between the Aβ-nanobodies and Aβ(1-40) and the Aβ(17-28) epitope provided K(D) values of approximately 150 and 700 nmol, respectively. Thus, the knowledge of the epitope may be highly useful for future studies of Aβ-aggregation (oligomerization and fibril formation) and for designing new aggregation inhibitors. Copyright © 2012 John Wiley

Hydrogen/deuterium exchange mass spectrometry and computational modeling reveal a discontinuous epitope of an antibody/TL1A Interaction.

Science.gov (United States)

Huang, Richard Y-C; Krystek, Stanley R; Felix, Nathan; Graziano, Robert F; Srinivasan, Mohan; Pashine, Achal; Chen, Guodong

2018-01-01

TL1A, a tumor necrosis factor-like cytokine, is a ligand for the death domain receptor DR3. TL1A, upon binding to DR3, can stimulate lymphocytes and trigger secretion of proinflammatory cytokines. Therefore, blockade of TL1A/DR3 interaction may be a potential therapeutic strategy for autoimmune and inflammatory diseases. Recently, the anti-TL1A monoclonal antibody 1 (mAb1) with a strong potency in blocking the TL1A/DR3 interaction was identified. Here, we report on the use of hydrogen/deuterium exchange mass spectrometry (HDX-MS) to obtain molecular-level details of mAb1's binding epitope on TL1A. HDX coupled with electron-transfer dissociation MS provided residue-level epitope information. The HDX dataset, in combination with solvent accessible surface area (SASA) analysis and computational modeling, revealed a discontinuous epitope within the predicted interaction interface of TL1A and DR3. The epitope regions span a distance within the approximate size of the variable domains of mAb1's heavy and light chains, indicating it uses a unique mechanism of action to block the TL1A/DR3 interaction.

The Neutralizing Linear Epitope of Human Herpesvirus 6A Glycoprotein B Does Not Affect Virus Infectivity.

Science.gov (United States)

Wakata, Aika; Kanemoto, Satoshi; Tang, Huamin; Kawabata, Akiko; Nishimura, Mitsuhiro; Jasirwan, Chyntia; Mahmoud, Nora Fahmy; Mori, Yasuko

2018-03-01

Human herpesvirus 6A (HHV-6A) glycoprotein B (gB) is a glycoprotein consisting of 830 amino acids and is essential for the growth of the virus. Previously, we reported that a neutralizing monoclonal antibody (MAb) called 87-y-13 specifically reacts with HHV-6A gB, and we identified its epitope residue at asparagine (Asn) 347 on gB. In this study, we examined whether the epitope recognized by the neutralizing MAb is essential for HHV-6A infection. We constructed HHV-6A bacterial artificial chromosome (BAC) genomes harboring substitutions at Asn347, namely, HHV-6A BACgB(N347K) and HHV-6A BACgB(N347A). These mutant viruses could be reconstituted and propagated in the same manner as the wild type and their revertants, and MAb 87-y-13 could not inhibit infection by either mutant. In a cell-cell fusion assay, Asn at position 347 on gB was found to be nonessential for cell-cell fusion. In addition, in building an HHV-6A gB homology model, we found that the epitope of the neutralizing MAb is located on domain II of gB and is accessible to solvents. These results indicate that Asn at position 347, the linear epitope of the neutralizing MAb, does not affect HHV-6A infectivity. IMPORTANCE Glycoprotein B (gB) is one of the most conserved glycoproteins among all herpesviruses and is a key factor for virus entry. Therefore, antibodies targeted to gB may neutralize virus entry. Human herpesvirus 6A (HHV-6A) encodes gB, which is translated to a protein of about 830 amino acids (aa). Using a monoclonal antibody (MAb) for HHV-6A gB, which has a neutralizing linear epitope, we analyzed the role of its epitope residue, N347, in HHV-6A infectivity. Interestingly, this gB linear epitope residue, N347, was not essential for HHV-6A growth. By constructing a homology model of HHV-6A gB, we found that N347 was located in the region corresponding to domain II. Therefore, with regard to its neutralizing activity against HHV-6A infection, the epitope on gB might be exposed to solvents

ScFv anti-heparan sulfate antibodies unexpectedly activate endothelial and cancer cells through p38 MAPK: implications for antibody-based targeting of heparan sulfate proteoglycans in cancer.

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Helena C Christianson

Full Text Available Tumor development requires angiogenesis and anti-angiogenic therapies have been introduced in the treatment of cancer. In this context, heparan sulfate proteoglycans (HSPGs emerge as interesting targets, owing to their function as co-receptors of major, pro-angiogenic factors. Accordingly, previous studies have suggested anti-tumor effects of heparin, i.e. over-sulfated HS, and various heparin mimetics; however, a significant drawback is their unspecific mechanism of action and potentially serious side-effects related to their anticoagulant properties. Here, we have explored the use of human ScFv anti-HS antibodies (αHS as a more rational approach to target HSPG function in endothelial cells (ECs. αHS were initially selected for their recognition of HS epitopes localized preferentially to the vasculature of patient glioblastoma tumors, i.e. highly angiogenic brain tumors. Unexpectedly, we found that these αHS exhibited potent pro-angiogenic effects in primary human ECs. αHS were shown to stimulate EC differentiation, which was associated with increased EC tube formation and proliferation. Moreover, αHS supported EC survival under hypoxia and starvation, i.e. conditions typical of the tumor microenvironment. Importantly, αHS-mediated proliferation was efficiently counter-acted by heparin and was absent in HSPG-deficient mutant cells, confirming HS-specific effects. On a mechanistic level, binding of αHS to HSPGs of ECs as well as glioblastoma cells was found to trigger p38 MAPK-dependent signaling resulting in increased proliferation. We conclude that several αHS that recognize HS epitopes abundant in the tumor vasculature may elicit a pro-angiogenic response, which has implications for the development of antibody-based targeting of HSPGs in cancer.

Congenital heart block maternal sera autoantibodies target an extracellular epitope on the α1G T-type calcium channel in human fetal hearts.

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Linn S Strandberg

Full Text Available Congenital heart block (CHB is a transplacentally acquired autoimmune disease associated with anti-Ro/SSA and anti-La/SSB maternal autoantibodies and is characterized primarily by atrioventricular (AV block of the fetal heart. This study aims to investigate whether the T-type calcium channel subunit α1G may be a fetal target of maternal sera autoantibodies in CHB.We demonstrate differential mRNA expression of the T-type calcium channel CACNA1G (α1G gene in the AV junction of human fetal hearts compared to the apex (18-22.6 weeks gestation. Using human fetal hearts (20-22 wks gestation, our immunoprecipitation (IP, Western blot analysis and immunofluorescence (IF staining results, taken together, demonstrate accessibility of the α1G epitope on the surfaces of cardiomyocytes as well as reactivity of maternal serum from CHB affected pregnancies to the α1G protein. By ELISA we demonstrated maternal sera reactivity to α1G was significantly higher in CHB maternal sera compared to controls, and reactivity was epitope mapped to a peptide designated as p305 (corresponding to aa305-319 of the extracellular loop linking transmembrane segments S5-S6 in α1G repeat I. Maternal sera from CHB affected pregnancies also reacted more weakly to the homologous region (7/15 amino acids conserved of the α1H channel. Electrophysiology experiments with single-cell patch-clamp also demonstrated effects of CHB maternal sera on T-type current in mouse sinoatrial node (SAN cells.Taken together, these results indicate that CHB maternal sera antibodies readily target an extracellular epitope of α1G T-type calcium channels in human fetal cardiomyocytes. CHB maternal sera also show reactivity for α1H suggesting that autoantibodies can target multiple fetal targets.

Generation of human antibody fragments recognizing distinct epitopes of the nucleocapsid (N SARS-CoV protein using a phage display approach

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Grasso Felicia

2005-09-01

Full Text Available Abstract Background Severe acute respiratory syndrome (SARS-CoV is a newly emerging virus that causes SARS with high mortality rate in infected people. Successful control of the global SARS epidemic will require rapid and sensitive diagnostic tests to monitor its spread, as well as, the development of vaccines and new antiviral compounds including neutralizing antibodies that effectively prevent or treat this disease. Methods The human synthetic single-chain fragment variable (scFv ETH-2 phage antibody library was used for the isolation of scFvs against the nucleocapsid (N protein of SARS-CoV using a bio panning-based strategy. The selected scFvs were characterized under genetics-molecular aspects and for SARS-CoV N protein detection in ELISA, western blotting and immunocytochemistry. Results Human scFv antibodies to N protein of SARS-CoV can be easily isolated by selecting the ETH-2 phage library on immunotubes coated with antigen. These in vitro selected human scFvs specifically recognize in ELISA and western blotting studies distinct epitopes in N protein domains and detect in immunohistochemistry investigations SARS-CoV particles in infected Vero cells. Conclusion The human scFv antibodies isolated and described in this study represent useful reagents for rapid detection of N SARS-CoV protein and SARS virus particles in infected target cells.

Next Generation Antibody Therapeutics Using Bispecific Antibody Technology.

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Igawa, Tomoyuki

2017-01-01

Nearly fifty monoclonal antibodies have been approved to date, and the market for monoclonal antibodies is expected to continue to grow. Since global competition in the field of antibody therapeutics is intense, we need to establish novel antibody engineering technologies to provide true benefit for patients, with differentiated product values. Bispecific antibodies are among the next generation of antibody therapeutics that can bind to two different target antigens by the two arms of immunoglobulin G (IgG) molecule, and are thus believed to be applicable to various therapeutic needs. Until recently, large scale manufacturing of human IgG bispecific antibody was impossible. We have established a technology, named asymmetric re-engineering technology (ART)-Ig, to enable large scale manufacturing of bispecific antibodies. Three examples of next generation antibody therapeutics using ART-Ig technology are described. Recent updates on bispecific antibodies against factor IXa and factor X for the treatment of hemophilia A, bispecific antibodies against a tumor specific antigen and T cell surface marker CD3 for cancer immunotherapy, and bispecific antibodies against two different epitopes of soluble antigen with pH-dependent binding property for the elimination of soluble antigen from plasma are also described.

Rapid profiling of the antigen regions recognized by serum antibodies using massively parallel sequencing of antigen-specific libraries.

KAUST Repository

Domina, Maria; Lanza Cariccio, Veronica; Benfatto, Salvatore; D'Aliberti, Deborah; Venza, Mario; Borgogni, Erica; Castellino, Flora; Biondo, Carmelo; D'Andrea, Daniel; Grassi, Luigi; Tramontano, Anna; Teti, Giuseppe; Felici, Franco; Beninati, Concetta

2014-01-01

There is a need for techniques capable of identifying the antigenic epitopes targeted by polyclonal antibody responses during deliberate or natural immunization. Although successful, traditional phage library screening is laborious and can map only some of the epitopes. To accelerate and improve epitope identification, we have employed massive sequencing of phage-displayed antigen-specific libraries using the Illumina MiSeq platform. This enabled us to precisely identify the regions of a model antigen, the meningococcal NadA virulence factor, targeted by serum antibodies in vaccinated individuals and to rank hundreds of antigenic fragments according to their immunoreactivity. We found that next generation sequencing can significantly empower the analysis of antigen-specific libraries by allowing simultaneous processing of dozens of library/serum combinations in less than two days, including the time required for antibody-mediated library selection. Moreover, compared with traditional plaque picking, the new technology (named Phage-based Representation OF Immuno-Ligand Epitope Repertoire or PROFILER) provides superior resolution in epitope identification. PROFILER seems ideally suited to streamline and guide rational antigen design, adjuvant selection, and quality control of newly produced vaccines. Furthermore, this method is also susceptible to find important applications in other fields covered by traditional quantitative serology.

Rapid profiling of the antigen regions recognized by serum antibodies using massively parallel sequencing of antigen-specific libraries.

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Maria Domina

Full Text Available There is a need for techniques capable of identifying the antigenic epitopes targeted by polyclonal antibody responses during deliberate or natural immunization. Although successful, traditional phage library screening is laborious and can map only some of the epitopes. To accelerate and improve epitope identification, we have employed massive sequencing of phage-displayed antigen-specific libraries using the Illumina MiSeq platform. This enabled us to precisely identify the regions of a model antigen, the meningococcal NadA virulence factor, targeted by serum antibodies in vaccinated individuals and to rank hundreds of antigenic fragments according to their immunoreactivity. We found that next generation sequencing can significantly empower the analysis of antigen-specific libraries by allowing simultaneous processing of dozens of library/serum combinations in less than two days, including the time required for antibody-mediated library selection. Moreover, compared with traditional plaque picking, the new technology (named Phage-based Representation OF Immuno-Ligand Epitope Repertoire or PROFILER provides superior resolution in epitope identification. PROFILER seems ideally suited to streamline and guide rational antigen design, adjuvant selection, and quality control of newly produced vaccines. Furthermore, this method is also susceptible to find important applications in other fields covered by traditional quantitative serology.

Rapid profiling of the antigen regions recognized by serum antibodies using massively parallel sequencing of antigen-specific libraries.

KAUST Repository

Domina, Maria

2014-12-04

There is a need for techniques capable of identifying the antigenic epitopes targeted by polyclonal antibody responses during deliberate or natural immunization. Although successful, traditional phage library screening is laborious and can map only some of the epitopes. To accelerate and improve epitope identification, we have employed massive sequencing of phage-displayed antigen-specific libraries using the Illumina MiSeq platform. This enabled us to precisely identify the regions of a model antigen, the meningococcal NadA virulence factor, targeted by serum antibodies in vaccinated individuals and to rank hundreds of antigenic fragments according to their immunoreactivity. We found that next generation sequencing can significantly empower the analysis of antigen-specific libraries by allowing simultaneous processing of dozens of library/serum combinations in less than two days, including the time required for antibody-mediated library selection. Moreover, compared with traditional plaque picking, the new technology (named Phage-based Representation OF Immuno-Ligand Epitope Repertoire or PROFILER) provides superior resolution in epitope identification. PROFILER seems ideally suited to streamline and guide rational antigen design, adjuvant selection, and quality control of newly produced vaccines. Furthermore, this method is also susceptible to find important applications in other fields covered by traditional quantitative serology.

Large Scale Genome Analysis Shows that the Epitopes for Broadly Cross-Reactive Antibodies Are Predominant in the Pandemic 2009 Influenza Virus A H1N1 Strain

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Edgar E. Lara-Ramírez

2013-11-01

Full Text Available The past pandemic strain H1N1 (A (H1N1pdm09 has now become a common component of current seasonal influenza viruses. It has changed the pre-existing immunity of the human population to succeeding infections. In the present study, a total of 14,210 distinct sequences downloaded from National Center for Biotechnology Information (NCBI database were used for the analysis. The epitope compositions in A (H1N1pdm09, classic seasonal strains, swine strains as well as highly virulent avian strain H5N1, identified with the aid of the Immune Epitope DataBase (IEDB, were compared at genomic level. The result showed that A (H1N1 pdm09 contains the 90% of B-cell epitopes for broadly cross-reactive antibodies (EBCA, which is in consonance with the recent reports on the experimental identification of new epitopes or antibodies for this virus and the binding tests with influenza virus protein HA of different subtypes. Our analysis supports that high proportional EBCA depends on the epitope pattern of A (H1N1pdm09 virus. This study may be helpful for better understanding of A (H1N1pdm09 and the production of new influenza vaccines.

Characterization of CD4 T Cell Epitopes of Infliximab and Rituximab Identified from Healthy Donors

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Moustafa Hamze

2017-05-01

Full Text Available The chimeric antibodies anti-CD20 rituximab (Rtx and anti-TNFα infliximab (Ifx induce antidrug antibodies (ADAs in many patients with inflammatory diseases. Because of the key role of CD4 T lymphocytes in the initiation of antibody responses, we localized the CD4 T cell epitopes of Rtx and Ifx. With the perspective to anticipate immunogenicity of therapeutic antibodies, identification of the CD4 T cell epitopes was performed using cells collected in healthy donors. Nine T cell epitopes were identified in the variable chains of both antibodies by deriving CD4 T cell lines raised against either Rtx or Ifx. The T cell epitopes often exhibited a good affinity for human leukocyte antigen (HLA-DR molecules and were part of the peptides identified by MHC-associated peptide proteomics assay from HLA-DR molecules of dendritic cells (DCs loaded with the antibodies. Two-third of the T cell epitopes identified from the healthy donors stimulated peripheral blood mononuclear cells from patients having developed ADAs against Rtx or Ifx and promoted the secretion of a diversity of cytokines. These data emphasize the predictive value of evaluating the T cell repertoire of healthy donors and the composition of peptides bound to HLA-DR of DCs to anticipate and prevent immunogenicity of therapeutic antibodies.

Arrayed antibody library technology for therapeutic biologic discovery.

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Bentley, Cornelia A; Bazirgan, Omar A; Graziano, James J; Holmes, Evan M; Smider, Vaughn V

2013-03-15

Traditional immunization and display antibody discovery methods rely on competitive selection amongst a pool of antibodies to identify a lead. While this approach has led to many successful therapeutic antibodies, targets have been limited to proteins which are easily purified. In addition, selection driven discovery has produced a narrow range of antibody functionalities focused on high affinity antagonism. We review the current progress in developing arrayed protein libraries for screening-based, rather than selection-based, discovery. These single molecule per microtiter well libraries have been screened in multiplex formats against both purified antigens and directly against targets expressed on the cell surface. This facilitates the discovery of antibodies against therapeutically interesting targets (GPCRs, ion channels, and other multispanning membrane proteins) and epitopes that have been considered poorly accessible to conventional discovery methods. Copyright © 2013. Published by Elsevier Inc.

Sensitivity of HIV-1 to neutralization by antibodies against O-linked carbohydrate epitopes despite deletion of O-glycosylation signals in the V3 loop

DEFF Research Database (Denmark)

Hansen, J E; Jansson, B; Gram, G J

1996-01-01

It has been suggested that threonine or serine residues in the V3 loop of HIV-1 gp120 are glycosylated with the short-chain O-linked oligosaccharides Tn or sialosyl-Tn that function as epitopes for broadly neutralizing carbohydrate specific antibodies. In this study we examined whether mutation....... Additionally, one of these T-A mutants (T308A) also abrogated the signal for N-glycosylation at N306 inside the V3-loop. The mutant clones were compared with the wild type virus as to sensitivity to neutralization with monoclonal and polyclonal antibodies specific for the tip of the V3 loop of BRU or for the O......-linked oligosaccharides Tn or sialosyl-Tn. Deletion of the N-linked oligosaccharide at N306 increased the neutralization sensitivity to antibodies specific for the tip of the loop, which indicates that N-linked glycosylation modulates the accessibility to this immunodominant epitope. However, none of the mutants...

Targeting Malignant Brain Tumors with Antibodies

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Rok Razpotnik

2017-09-01

Full Text Available Antibodies have been shown to be a potent therapeutic tool. However, their use for targeting brain diseases, including neurodegenerative diseases and brain cancers, has been limited, particularly because the blood–brain barrier (BBB makes brain tissue hard to access by conventional antibody-targeting strategies. In this review, we summarize new antibody therapeutic approaches to target brain tumors, especially malignant gliomas, as well as their potential drawbacks. Many different brain delivery platforms for antibodies have been studied such as liposomes, nanoparticle-based systems, cell-penetrating peptides (CPPs, and cell-based approaches. We have already shown the successful delivery of single-chain fragment variable (scFv with CPP as a linker between two variable domains in the brain. Antibodies normally face poor penetration through the BBB, with some variants sufficiently passing the barrier on their own. A “Trojan horse” method allows passage of biomolecules, such as antibodies, through the BBB by receptor-mediated transcytosis (RMT. Such examples of therapeutic antibodies are the bispecific antibodies where one binding specificity recognizes and binds a BBB receptor, enabling RMT and where a second binding specificity recognizes an antigen as a therapeutic target. On the other hand, cell-based systems such as stem cells (SCs are a promising delivery system because of their tumor tropism and ability to cross the BBB. Genetically engineered SCs can be used in gene therapy, where they express anti-tumor drugs, including antibodies. Different types and sources of SCs have been studied for the delivery of therapeutics to the brain; both mesenchymal stem cells (MSCs and neural stem cells (NSCs show great potential. Following the success in treatment of leukemias and lymphomas, the adoptive T-cell therapies, especially the chimeric antigen receptor-T cells (CAR-Ts, are making their way into glioma treatment as another type of cell

CD4+ T cells targeting dominant and cryptic epitopes from Bacillus anthracis Lethal Factor

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Stephanie eAscough

2016-01-01

Full Text Available Anthrax is an endemic infection in many countries, particularly in the developing world. The causative agent, Bacillus anthracis, mediates disease through the secretion of binary exotoxins. Until recently, research into adaptive immunity targeting this bacterial pathogen has largely focused on the humoral response to these toxins. There is, however, growing recognition that cellular immune responses involving IFNγ producing CD4+ T cells also contribute significantly to a protective memory response. An established concept in adaptive immunity to infection is that during infection of host cells, new microbial epitopes may be revealed, leading to immune recognition of so called ‘cryptic’ or ‘subdominant’ epitopes. We analysed the response to both cryptic and immunodominant T cell epitopes derived from the toxin component lethal factor and presented by a range of HLA-DR alleles. Using IFNγ-ELISPOT assays we characterised epitopes that elicited a response following immunisation with synthetic peptide and the whole protein and tested their capacities to bind purified HLA-DR molecules in vitro. We found that DR1 transgenics demonstrated T cell responses to a greater number of domain III cryptic epitopes than other HLA-DR transgenics, and that this pattern was repeated with the immunodominant epitopes, a greater proportion of these epitopes induced a T cell response when presented within the context of the whole protein. Immunodominant epitopes LF457-476 and LF467-487 were found to induce a T cell response to the peptide, as well as to the whole native LF protein in DR1 and DR15, but not in DR4 trangenics. The analysis of Domain I revealed the presence of several unique cryptic epitopes all of which showed a strong to moderate relative binding affinity to HLA-DR4 molecules. However, none of the cryptic epitopes from either domain III or I displayed notably high binding affinities across all HLA-DR alleles assayed. These responses were

Utilizing nanobody technology to target non-immunodominant domains of VAR2CSA

DEFF Research Database (Denmark)

Ditlev, Sisse B; Florea, Raluca; Nielsen, Morten A

2014-01-01

adhesion. However, the development of a VAR2CSA adhesion-blocking vaccine remains challenging due to (i) the large size of VAR2CSA and (ii) the extensive immune selection for polymorphisms and thereby non-neutralizing B-cell epitopes. Camelid heavy-chain-only antibodies (HcAbs) are known to target epitopes...... that are less immunogenic to classical IgG and, due to their small size and protruding antigen-binding loop, able to reach and recognize cryptic, conformational epitopes which are inaccessible to conventional antibodies. The variable heavy chain (VHH) domain is the antigen-binding site of camelid HcAbs, the so...

Immunization with a novel chimeric peptide representing B and T cell epitopes from HER2 extracellular domain (HER2 ECD) for breast cancer.

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Mahdavi, Manijeh; Keyhanfar, Mehrnaz; Jafarian, Abbas; Mohabatkar, Hassan; Rabbani, Mohammad

2014-12-01

Because of direct stimulating immune system against disease, vaccination or active immunotherapy is preferable compared to passive immunotherapy. For this purpose, a newly designed chimeric peptide containing epitopes for both B and T cells from HER2 ECD subdomain III was proposed. To evaluate the effects of the active immunization, a discontinuous B cell epitope peptide was selected based on average antigenicity by bioinformatics analysis. The selected peptide was collinearly synthesized as a chimera with a T helper epitope from the protein sequence of measles virus fusion (208-302) using the GPSL linker. Three mice were immunized with the chimeric peptide. Reactive antibodies with HER2 protein in ELISA and immunofluorescence assays with no cross-reactivity were generated. The 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay indicated that the anti-peptide sera had inhibitory effects on proliferation of SK-BR-3 cells. Hence, the newly designed, discontinuous chimeric peptide representing B and T cell epitopes from subdomain III of HER2-ECD can form the basis for future vaccines design, where these data can be applied for monoclonal antibody production targeting the distinct epitope of HER2 receptor compared to the two broadly used anti-HER2 monoclonal antibodies, Herceptin and pertuzumab.

Human broadly neutralizing antibodies to the envelope glycoprotein complex of hepatitis C virus

DEFF Research Database (Denmark)

Giang, Erick; Dorner, Marcus; Prentoe, Jannick C

2012-01-01

, and an effective vaccine should target conserved T- and B-cell epitopes of the virus. Conserved B-cell epitopes overlapping the CD81 receptor-binding site (CD81bs) on the E2 viral envelope glycoprotein have been reported previously and provide promising vaccine targets. In this study, we isolated 73 human m......Abs recognizing five distinct antigenic regions on the virus envelope glycoprotein complex E1E2 from an HCV-immune phage-display antibody library by using an exhaustive-panning strategy. Many of these mAbs were broadly neutralizing. In particular, the mAb AR4A, recognizing a discontinuous epitope outside the CD81......bs on the E1E2 complex, has an exceptionally broad neutralizing activity toward diverse HCV genotypes and protects against heterologous HCV challenge in a small animal model. The mAb panel will be useful for the design and development of vaccine candidates to elicit broadly neutralizing antibodies...

Production, Characterization, and Epitope Mapping of Monoclonal Antibodies Against Different Subtypes of Rabbit Hemorrhagic Disease Virus (RHDV).

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Kong, Desheng; Liu, Jiasen; Jiang, Qian; Yu, Zuo; Hu, Xiaoliang; Guo, Dongchun; Huang, Qianqian; Jiao, Meihui; Qu, Liandong

2016-02-16

In 2010, a new rabbit hemorrhagic disease virus (RHDV) variant, designated RHDV2, was identified for the first time in Italy. Studies have shown that RHDV2 differs from RHDV1 (traditional RHDV) in terms of its antigenic profile and genetic characteristics. The VP60 protein of RHDV is a structural protein that plays important roles in viral replication, assembly, and immunogenicity. In this study, we immunized BALB/c mice with recombinant VP60 proteins from different RHDV subtypes. After three rounds of subcloning, type-specific positive hybridoma clones of RHDV1 and RHDV2 were further identified by an enzyme-linked immunosorbent assay, Western blotting, and an indirect immunofluorescence assay. Finally, three monoclonal antibodies (MAbs) (1D6, 1H2, and 3F2) that only recognize RHDV1, and four MAbs (1G2, 2C1, 3B7, and 5D6) that only recognize RHDV2 were identified. The epitopes recognized by these MAbs were mapped by Western blotting. Sequence analysis showed that the epitope sequences recognized by 1D6, 1H2, and 3F2 are highly conserved (98%) among RHDV1 strains, whereas the epitope sequences recognized by 1G2, 2C1, 3B7, and 5D6 are 100% conserved among RHDV2 strains. The high conservation of the epitope sequence showed that the screened MAbs were type-specific, and that they could distinguish different RHDV subtypes.

A single point in protein trafficking by Plasmodium falciparum determines the expression of major antigens on the surface of infected erythrocytes targeted by human antibodies.

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Chan, Jo-Anne; Howell, Katherine B; Langer, Christine; Maier, Alexander G; Hasang, Wina; Rogerson, Stephen J; Petter, Michaela; Chesson, Joanne; Stanisic, Danielle I; Duffy, Michael F; Cooke, Brian M; Siba, Peter M; Mueller, Ivo; Bull, Peter C; Marsh, Kevin; Fowkes, Freya J I; Beeson, James G

2016-11-01

Antibodies to blood-stage antigens of Plasmodium falciparum play a pivotal role in human immunity to malaria. During parasite development, multiple proteins are trafficked from the intracellular parasite to the surface of P. falciparum-infected erythrocytes (IEs). However, the relative importance of different proteins as targets of acquired antibodies, and key pathways involved in trafficking major antigens remain to be clearly defined. We quantified antibodies to surface antigens among children, adults, and pregnant women from different malaria-exposed regions. We quantified the importance of antigens as antibody targets using genetically engineered P. falciparum with modified surface antigen expression. Genetic deletion of the trafficking protein skeleton-binding protein-1 (SBP1), which is involved in trafficking the surface antigen PfEMP1, led to a dramatic reduction in antibody recognition of IEs and the ability of human antibodies to promote opsonic phagocytosis of IEs, a key mechanism of parasite clearance. The great majority of antibody epitopes on the IE surface were SBP1-dependent. This was demonstrated using parasite isolates with different genetic or phenotypic backgrounds, and among antibodies from children, adults, and pregnant women in different populations. Comparisons of antibody reactivity to parasite isolates with SBP1 deletion or inhibited PfEMP1 expression suggest that PfEMP1 is the dominant target of acquired human antibodies, and that other P. falciparum IE surface proteins are minor targets. These results establish SBP1 as part of a critical pathway for the trafficking of major surface antigens targeted by human immunity, and have key implications for vaccine development, and quantifying immunity in populations.

Epitopes in α8β1 and other RGD-binding integrins delineate classes of integrin-blocking antibodies and major binding loops in α subunits.

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Nishimichi, Norihisa; Kawashima, Nagako; Yokosaki, Yasuyuki

2015-09-09

Identification of epitopes for integrin-blocking monoclonal antibodies (mAbs) has aided our understanding of structure-function relationship of integrins. We mapped epitopes of chicken anti-integrin-α8-subunit-blocking mAbs by mutational analyses, examining regions that harboured all mapped epitopes recognized by mAbs against other α-subunits in the RGD-binding-integrin subfamily. Six mAbs exhibited blocking function, and these mAbs recognized residues on the same W2:41-loop on the top-face of the β-propeller. Loop-tips sufficiently close to W2:41 (face was identified as an additional component of the epitope of one antibody, clone YZ5. Binding sequences on the two loops were conserved in virtually all mammals, and that on W3:34 was also conserved in chickens. These indicate 1) YZ5 binds both top and bottom loops, and the binding to W3:34 is by interactions to conserved residues between immunogen and host species, 2) five other blocking mAbs solely bind to W2:41 and 3) the α8 mAbs would cross-react with most mammals. Comparing with the mAbs against the other α-subunits of RGD-integrins, two classes were delineated; those binding to "W3:34 and an top-loop", and "solely W2:41", accounting for 82% of published RGD-integrin-mAbs.

Sera of children with hepatitis C infection and anti-liver-kidney microsome-1 antibodies recognize different CYP2D6 epitopes than adults with LKM+/HCV+ sera.

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Herzog, D; Yamamoto, A M; Jara, P; Maggiore, G; Sarles, J; Alvarez, F

1999-11-01

Liver-kidney microsome type 1 (LKM1) antibodies are specific markers of autoimmune hepatitis (AIH) type 2. Antibodies to LKM1 have been found in 2% to 3% of adults infected with hepatitis C virus (HCV) without AIH. Thirty percent of these antibodies are directed against linear sequences of CYP2D6 protein. LKM1 antibodies in HCV+/LKM1+ sera and in sera of AIH patients do not recognize the same CYP2D6 epitopes. The current study was conducted to determine whether LKM1 antibodies in HCV+/LKM1+ children's sera are the result of the same immune response as the antibodies described in AIH type 2 and in HCV+/LKM1+ adult patients. Sera from 10 HCV+/LKM1+ children were tested against human liver microsomal and cytosolic proteins by Western blot analysis and against synthetic peptides of the CYP2D6 sequence between amino acids 200 and 429 by dot blot. The same sera were tested against radiolabeled CYP2D6 by immunoprecipitation. Four of 10 sera tested by Western blot analysis showed immunoglobulin (Ig) G-type antibodies against CYP2D6, and 2 had antibodies against proteins of 58, 66, and 84 kDa. One of the sera also contained IgM-type anti-66-kDa and 84-kDa proteins. The radioligand test detected anti-CYP2D6 antibodies in 9 of 10 patients. Five of the anti-CYP2D6-positive sera recognized a peptide between amino acids 200 and 429 including amino acids 254-271. Most HCV+/LKM1+ sera from children recognize conformational epitopes of the CYP2D6 antigen, and half recognize linear epitopes. Some HCV+/LKM1+ sera demonstrated antibodies against the AIH type 2 main antigenic site of the CYP2D6. Screening of HCV RNA should be performed before starting treatment of presumed autoimmune hepatitis associated with LKM1.

Identification and characterization of B-cell epitopes in the DBL4e domain of VAR2CSA

DEFF Research Database (Denmark)

Ditlev, Sisse B; Nielsen, Morten A; Resende, Mafalda

2012-01-01

and is the leading candidate for a placental malaria vaccine. Antibodies induced in rats against the recombinant DBL4e domain of VAR2CSA inhibit the binding of a number of laboratory and field parasite isolates to CSA. In this study, we used a DBL4e peptide-array to identify epitopes targeted by DBL4e...... might be involved in the induction of inhibitory antibodies induced by the recombinant DBL4e domain....

Neutralization of tier-2 viruses and epitope profiling of plasma antibodies from human immunodeficiency virus type 1 infected donors from India.

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Raiees Andrabi

Full Text Available Broadly cross neutralizing antibodies (NAbs are generated in a group of HIV-1 infected individuals during the natural infection, but little is known about their prevalence in patients infected with viral subtypes from different geographical regions. We tested here the neutralizing efficiency of plasma antibodies from 80 HIV-1 infected antiretroviral drug naive patients against a panel of subtype-B and C tier 2 viruses. We detected cross-neutralizing antibodies in approximately 19-27% of the plasma, however the subtype-C specific neutralization efficiency predominated (p = 0.004. The neutralizing activity was shown to be exclusively mediated by the immunoglobulin G (IgG fraction in the representative plasma samples. Epitope mapping of three, the most cross-neutralizing plasma (CNP AIIMS206, AIIMS239 and AIIMS249 with consensus-C overlapping envelope peptides revealed ten different binding specificities with only V3 and IDR being common. The V3 and IDR were highly antigenic regions but no correlation between their reciprocal Max50 binding titers and neutralization was observed. In addition, the neutralizing activity of CNP was not substantially reduced by V3 and gp41 peptides except a modest contribution of MPER peptide. The MPER was rarely recognized by plasma antibodies though antibody depletion and competition experiments demonstrated MPER dependent neutralization in two out of three CNP. Interestingly, the binding specificity of one of the CNP (AIIMS206 overlapped with broadly neutralizing mAb 2F5 epitope. Overall, the data suggest that, despite the low immunogenicity of HIV-1 MPER, the antibodies directed to this region may serve as crucial reagents for HIV-1 vaccine design.

The first human epitope map of the alphaviral E1 and E2 proteins reveals a new E2 epitope with significant virus neutralizing activity.

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Ann R Hunt

2010-07-01

Full Text Available Venezuelan equine encephalitis virus (VEEV is responsible for VEE epidemics that occur in South and Central America and the U.S. The VEEV envelope contains two glycoproteins E1 (mediates cell membrane fusion and E2 (binds receptor and elicits virus neutralizing antibodies. Previously we constructed E1 and E2 epitope maps using murine monoclonal antibodies (mMAbs. Six E2 epitopes (E2(c,d,e,f,g,h bound VEEV-neutralizing antibody and mapped to amino acids (aa 182-207. Nothing is known about the human antibody repertoire to VEEV or epitopes that engage human virus-neutralizing antibodies. There is no specific treatment for VEE; however virus-neutralizing mMAbs are potent protective and therapeutic agents for mice challenged with VEEV by either peripheral or aerosol routes. Therefore, fully human MAbs (hMAbs with virus-neutralizing activity should be useful for prevention or clinical treatment of human VEE.We used phage-display to isolate VEEV-specific hFabs from human bone marrow donors. These hFabs were characterized by sequencing, specificity testing, VEEV subtype cross-reactivity using indirect ELISA, and in vitro virus neutralization capacity. One E2-specific neutralizing hFAb, F5n, was converted into IgG, and its binding site was identified using competitive ELISA with mMAbs and by preparing and sequencing antibody neutralization-escape variants.Using 11 VEEV-reactive hFabs we constructed the first human epitope map for the alphaviral surface proteins E1 and E2. We identified an important neutralization-associated epitope unique to the human immune response, E2 aa115-119. Using a 9 A resolution cryo-electron microscopy map of the Sindbis virus E2 protein, we showed the probable surface location of this human VEEV epitope.The VEEV-neutralizing capacity of the hMAb F5 nIgG is similar to that exhibited by the humanized mMAb Hy4 IgG. The Hy4 IgG has been shown to limit VEEV infection in mice both prophylactically and therapeutically. Administration

Discovery of novel targets for multi-epitope vaccines: Screening of HIV-1 genomes using association rule mining

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Piontkivska Helen

2009-07-01

Full Text Available Abstract Background Studies have shown that in the genome of human immunodeficiency virus (HIV-1 regions responsible for interactions with the host's immune system, namely, cytotoxic T-lymphocyte (CTL epitopes tend to cluster together in relatively conserved regions. On the other hand, "epitope-less" regions or regions with relatively low density of epitopes tend to be more variable. However, very little is known about relationships among epitopes from different genes, in other words, whether particular epitopes from different genes would occur together in the same viral genome. To identify CTL epitopes in different genes that co-occur in HIV genomes, association rule mining was used. Results Using a set of 189 best-defined HIV-1 CTL/CD8+ epitopes from 9 different protein-coding genes, as described by Frahm, Linde & Brander (2007, we examined the complete genomic sequences of 62 reference HIV sequences (including 13 subtypes and sub-subtypes with approximately 4 representative sequences for each subtype or sub-subtype, and 18 circulating recombinant forms. The results showed that despite inclusion of recombinant sequences that would be expected to break-up associations of epitopes in different genes when two different genomes are recombined, there exist particular combinations of epitopes (epitope associations that occur repeatedly across the world-wide population of HIV-1. For example, Pol epitope LFLDGIDKA is found to be significantly associated with epitopes GHQAAMQML and FLKEKGGL from Gag and Nef, respectively, and this association rule is observed even among circulating recombinant forms. Conclusion We have identified CTL epitope combinations co-occurring in HIV-1 genomes including different subtypes and recombinant forms. Such co-occurrence has important implications for design of complex vaccines (multi-epitope vaccines and/or drugs that would target multiple HIV-1 regions at once and, thus, may be expected to overcome challenges

C595 antibody: A potential vector for targeted alpha therapy

International Nuclear Information System (INIS)

Perkins, A.C.; Allen, B.J.

2005-01-01

Full text: Mucins are high molecular-weight heavily glycosylated glycoproteins with many oligosaccharide side-chains, linked to a protein backbone called apomucin. A total of 19 different mucin genes (MUC1-MUC4, MUC5B, MUC5AC, MUC6-MUC18) have been identified to date. Mucins are present on the surface of most epithelial cells and play a role in their protection and lubrication. In cancer cells the mucin molecule becomes altered, thus representing an important target for diagnosis and therapy. Urinary epithelial mucin1 (MUC1) is found to be frequently up-regulated and abnormally glycosylated in a number of common malignancies, including breast, bladder, colon, ovarian and gastric cancer. The monoclonal antibody C595 is an IgG3 murine MAb raised against the protein core of human MUC1. Epitope mapping has shown that C595 recognizes a tetrapeptide motif (RPAP) within the protein core of MUC1 mucin that contains a large domain of multiples of a highly conserved 20-amino-acid-repeat sequence (PDTRPAPGSTAPPAHGVTSA). This antibody has previously been radiolabelled with 99m Tc and 111 In and used for imaging a range of tumour types including ovary, breast and bladder. The antibody has also been radiolabelled with 67 Cu and 188 Re for the therapy of superficial bladder cancer. More recently we have investigated the pre-clinical use of the C595 antibody for targeted alpha therapy using 213 Bi which emits alpha particles with high linear energy transfer (LET), short range (80 m) radiation and has a short physical half-life of 45.6 minutes. Alpha particles are some 7300 times heavier than beta particles and in theory, following binding of an alpha immunocongugates to the target, a large fraction of the alpha particle energy is delivered to cancer cells, with minimal concomitant radiation of normal tissues. 213 Bi was produced from the 225 Ac/ 213 Bi generator. For antibody conjugation the chelator, cyclic diethylenetriaminepentacetic acid anhydride (DTPA) was used. Initial

Comparative characteristic of the methods of protein antigens epitope mapping

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O. Yu. Galkin

2014-08-01

Full Text Available Comparative analysis of experimental methods of epitope mapping of protein antigens has been carried out. The vast majority of known techniques are involved in immunochemical study of the interaction of protein molecules or peptides with antibodies of corresponding specifici­ty. The most effective and widely applicable metho­dological techniques are those that use synthetic and genetically engineered peptides. Over the past 30 years, these groups of methods have travelled a notable evolutionary path up to the maximum automation and the detection of antigenic determinants of various types (linear and conformational epitopes, and mimotopes. Most of epitope searching algorithms were integrated into a computer program, which greatly facilitates the analysis of experimental data and makes it possible to create spatial models. It is possible to use comparative epitope mapping for solving the applied problems; this less time-consuming method is based on the analysis of competition between different antibodies interactions with the same antigen. The physical method of antigenic structure study is X-ray analysis of antigen-antibody complexes, which may be applied only to crystallizing­ proteins, and nuclear magnetic resonance.

Characterization and specificity of the linear epitope of the enterovirus 71 VP2 protein

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Kiener Tanja K

2012-02-01

Full Text Available Abstract Background Enterovirus 71 (EV71 has emerged as a major causative agent of hand, foot and mouth disease in the Asia-Pacific region over the last decade. Hand, foot and mouth disease can be caused by different etiological agents from the enterovirus family, mainly EV71 and coxsackieviruses, which are genetically closely related. Nevertheless, infection with EV71 may occasionally lead to high fever, neurologic complications and the emergence of a rapidly fatal syndrome of pulmonary edema associated with brainstem encephalitis. The rapid progression and high mortality of severe EV71 infection has highlighted the need for EV71-specific diagnostic and therapeutic tools. Monoclonal antibodies are urgently needed to specifically detect EV71 antigens from patient specimens early in the infection process. Furthermore, the elucidation of viral epitopes will contribute to the development of targeted therapeutics and vaccines. Results We have identified the monoclonal antibody 7C7 from a screen of hybridoma cells derived from mice immunized with the EV71-B5 strain. The linear epitope of 7C7 was mapped to amino acids 142-146 (EDSHP of the VP2 capsid protein and was characterized in detail. Mutational analysis of the epitope showed that the aspartic acid to asparagine mutation of the EV71 subgenogroup A (BrCr strain did not interfere with antibody recognition. In contrast, the serine to threonine mutation at position 144 of VP2, present in recently emerged EV71-C4 China strains, abolished antigenicity. Mice injected with this virus strain did not produce any antibodies against the VP2 protein. Immunofluorescence and Western blotting confirmed that 7C7 specifically recognized EV71 subgenogroups and did not cross-react to Coxsackieviruses 4, 6, 10, and 16. 7C7 was successfully used as a detection antibody in an antigen-capture ELISA assay. Conclusions Detailed mapping showed that the VP2 protein of Enterovirus 71 contains a single, linear, non

Should we ignore western blots when selecting antibodies for other applications?

DEFF Research Database (Denmark)

Uhlén, Mathias

2017-01-01

.In the Human Protein Atlas (HPA) program, we have validated more than 24,000 in-house-generated antibodies directed to 17,000 human target proteins2. Although there is often a correlation between performance in different applications, we have observed many examples of antibodies that show strong support...... applications and that this influences the epitopes exposed on the target protein, which might have profound consequences for the ability of a given antibody to bind specifically to its target. As an example, proteins that are analyzed by immunohistochemistry (IHC) are normally first cross-linked with formalin.......In conclusion, western blot and protein array analyses can indeed be useful tools when selecting specific antibodies for other applications. The use of these methods is encouraged both for antibody providers and users, and antibodies with signs of cross-reactivity in these applications should be treated...

Inhibitory mechanism of peptides and antibodies targeting murine urokinase-type plasminogen activator

DEFF Research Database (Denmark)

Liu, Zhuo

2012-01-01

drugs, a detailed mechanistic understanding must be obtained. One peptide and two antibodies were studied in this thesis. First, an engineered cyclic peptide, mupain-1-16 with an unnatural amino acid in the P1 position and the sequence CPAYS[L-3-(N-Amidino-4-piperidyl)alanine]YLDC was investigated...... different conformational and inhibitory mechanisms both in vivo and in vitro. Their similar epitopes, but different functions revealed two different allosteric regulation mechanisms for antibodies binding to serine proteases. Both the peptidic inhibitors and the allosteric mechanisms of uPA are believed...

[Immunoreactivity of chimeric proteins carrying poliovirus epitopes on the VP6 of rotavirus as a vector].

Science.gov (United States)

Pan, X-X; Zhao, B-X; Teng, Y-M; Xia, W-Y; Wang, J; Li, X-F; Liao, G-Y; Yang, С; Chen, Y-D

2016-01-01

Rotavirus and poliovirus continue to present significant risks and burden of disease to children in developing countries. Developing a combined vaccine may effectively prevent both illnesses and may be advantageous in terms of maximizing compliance and vaccine coverage at the same visit. Recently, we sought to generate a vaccine vector by incorporating multiple epitopes into the rotavirus group antigenic protein, VP6. In the present study, a foreign epitope presenting a system using VP6 as a vector was created with six sites on the outer surface of the vector that could be used for insertion of foreign epitopes, and three VP6-based PV1 epitope chimeric proteins were constructed. The chimeric proteins were confirmed by immunoblot, immunofluorescence assay, and injected into guinea pigs to analyze the epitope-specific humoral response. Results showed that these chimeric proteins reacted with anti-VP6F and -PV1 antibodies, and elicited antibodies against both proteins in guinea pigs. Antibodies against the chimeric proteins carrying PV1 epitopes neutralized rotavirus Wa and PV1 infection in vitro. Our study contributes to a better understanding of the use of VP6-based vectors as multiple-epitope delivery vehicles and the epitopes displayed in this form could be considered for development of epitope-based vaccines against rotavirus and poliovirus.

Epitope mapping for monoclonal antibody reveals the activation mechanism for αVβ3 integrin.

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Tetsuji Kamata

Full Text Available Epitopes for a panel of anti-αVβ3 monoclonal antibodies (mAbs were investigated to explore the activation mechanism of αVβ3 integrin. Experiments utilizing αV/αIIb domain-swapping chimeras revealed that among the nine mAbs tested, five recognized the ligand-binding β-propeller domain and four recognized the thigh domain, which is the upper leg of the αV chain. Interestingly, the four mAbs included function-blocking as well as non-functional mAbs, although they bound at a distance from the ligand-binding site. The epitopes for these four mAbs were further determined using human-to-mouse αV chimeras. Among the four, P3G8 recognized an amino acid residue, Ser-528, located on the side of the thigh domain, while AMF-7, M9, and P2W7 all recognized a common epitope, Ser-462, that was located close to the α-genu, where integrin makes a sharp bend in the crystal structure. Fibrinogen binding studies for cells expressing wild-type αVβ3 confirmed that AMF-7, M9, and P2W7 were inhibitory, while P3G8 was non-functional. However, these mAbs were all unable to block binding when αVβ3 was constrained in its extended conformation. These results suggest that AMF-7, M9, and P2W7 block ligand binding allosterically by stabilizing the angle of the bend in the bent conformation. Thus, a switchblade-like movement of the integrin leg is indispensable for the affinity regulation of αVβ3 integrin.

Mutation of neutralizing/antibody-dependent enhancing epitope on spike protein and 7b gene of feline infectious peritonitis virus: influences of viral replication in monocytes/macrophages and virulence in cats.

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Takano, Tomomi; Tomiyama, Yoshika; Katoh, Yasuichiroh; Nakamura, Michiyo; Satoh, Ryoichi; Hohdatsu, Tsutomu

2011-03-01

We previously prepared neutralizing monoclonal antibody (MAb)-resistant (mar) mutant viruses using a laboratory strain feline infectious peritonitis virus (FIPV) 79-1146 (Kida et al., 1999). Mar mutant viruses are mutated several amino acids of the neutralizing epitope of Spike protein, compared with the parent strain, FIPV 79-1146. We clarified that MAb used to prepare mar mutant viruses also lost its activity to enhance homologous mar mutant viruses, strongly suggesting that neutralizing and antibody-dependent enhancing epitopes are present in the same region in the strain FIPV 79-1146. We also discovered that amino acid mutation in the neutralizing epitope reduced viral replication in monocytes/macrophages. We also demonstrated that the mutation or deletion of two nucleotides in 7b gene abrogate the virulence of strain FIPV 79-1146. Copyright © 2011 Elsevier B.V. All rights reserved.

Monoclonal antibodies to meningococcal factor H binding protein with overlapping epitopes and discordant functional activity.

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Giuntini, Serena; Beernink, Peter T; Reason, Donald C; Granoff, Dan M

2012-01-01

Meningococcal factor H binding protein (fHbp) is a promising vaccine candidate. Anti-fHbp antibodies can bind to meningococci and elicit complement-mediated bactericidal activity directly. The antibodies also can block binding of the human complement down-regulator, factor H (fH). Without bound fH, the organism would be expected to have increased susceptibility to bacteriolysis. Here we describe bactericidal activity of two anti-fHbp mAbs with overlapping epitopes in relation to their different effects on fH binding and bactericidal activity. Both mAbs recognized prevalent fHbp sequence variants in variant group 1. Using yeast display and site-specific mutagenesis, binding of one of the mAbs (JAR 1, IgG3) to fHbp was eliminated by a single amino acid substitution, R204A, and was decreased by K143A but not by R204H or D142A. The JAR 1 epitope overlapped that of previously described mAb (mAb502, IgG2a) whose binding to fHbp was eliminated by R204A or R204H substitutions, and was decreased by D142A but not by K143A. Although JAR 1 and mAb502 appeared to have overlapping epitopes, only JAR 1 inhibited binding of fH to fHbp and had human complement-mediated bactericidal activity. mAb502 enhanced fH binding and lacked human complement-mediated bactericidal activity. To control for confounding effects of different mouse IgG subclasses on complement activation, we created chimeric mAbs in which the mouse mAb502 or JAR 1 paratopes were paired with human IgG1 constant regions. While both chimeric mAbs showed similar binding to fHbp, only JAR 1, which inhibited fH binding, had human complement-mediated bactericidal activity. The lack of human complement-mediated bactericidal activity by anti-fHbp mAb502 appeared to result from an inability to inhibit binding of fH. These results underscore the importance of inhibition of fH binding for anti-fHbp mAb bactericidal activity.

The use of a cocktail of single chain Fv antibody fragments to improve the in vitro and in vivo targeting of melanoma

International Nuclear Information System (INIS)

Pacifico, M.D.; Pearl, R.A.; Kupsch, J.M.

2006-01-01

Radio scintigraphy using single chain antibody fragments (scFvs) offers a potenti al means of early detection of melanoma metastases. However, previous studies have shown suboptimal levels of tumour localization and nonspecific background accumulation which may be due to antigen heterogeneity. We aimed to improve tumour localization by using a cocktail of different scFvs targeting different epitopes on melanoma cells. We have previously developed three scFvs against distinct and highly tumour-specific melanoma cell-surface antigens by chain shuffling and antibody phage selection on melanoma cells. Three scFvs, RAFT3, B3 and B4 were labeled with 1 25I odine and tested both individually and as a cocktail in a nude mouse xenograft model far human melanoma. Results demonstrated improved tumour localization in vivo when compared to the individual scFvs. Tumour uptake of the cocktail at l hour was 24.220% ID/g (injected dose/gram) compared with 2.854%, 2.263% and 1.355% far B4, RAFT3 and B3, respectively, when injected individually. In addition, the cocktail exhibited significantly superior tumour to normal tissue ratios far muscle and spleen (p<0.05). A combination or cocktail of scFv clones may have an advantage aver individual scFvs far melanoma targeting in patients because of heterogeneity in the expression of different epitopes of antigens on melanoma cells

Conservation and diversity of influenza A H1N1 HLA-restricted T cell epitope candidates for epitope-based vaccines.

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Paul Thiamjoo Tan

2010-01-01

Full Text Available The immune-related evolution of influenza viruses is exceedingly complex and current vaccines against influenza must be reformulated for each influenza season because of the high degree of antigenic drift among circulating influenza strains. Delay in vaccine production is a serious problem in responding to a pandemic situation, such as that of the current H1N1 strain. Immune escape is generally attributed to reduced antibody recognition of the viral hemagglutinin and neuraminidase proteins whose rate of mutation is much greater than that of the internal non-structural proteins. As a possible alternative, vaccines directed at T cell epitope domains of internal influenza proteins, that are less susceptible to antigenic variation, have been investigated.HLA transgenic mouse strains expressing HLA class I A*0201, A*2402, and B*0702, and class II DRB1*1501, DRB1*0301 and DRB1*0401 were immunized with 196 influenza H1N1 peptides that contained residues of highly conserved proteome sequences of the human H1N1, H3N2, H1N2, H5N1, and avian influenza A strains. Fifty-four (54 peptides that elicited 63 HLA-restricted peptide-specific T cell epitope responses were identified by IFN-gamma ELISpot assay. The 54 peptides were compared to the 2007-2009 human H1N1 sequences for selection of sequences in the design of a new candidate H1N1 vaccine, specifically targeted to highly-conserved HLA-restricted T cell epitopes.Seventeen (17 T cell epitopes in PB1, PB2, and M1 were selected as vaccine targets based on sequence conservation over the past 30 years, high functional avidity, non-identity to human peptides, clustered localization, and promiscuity to multiple HLA alleles. These candidate vaccine antigen sequences may be applicable to any avian or human influenza A virus.

Universal antibodies against the highly conserved influenza fusion peptide cross-neutralize several subtypes of influenza A virus

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Hashem, Anwar M. [Centre for Vaccine Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada, Ottawa, ON (Canada); Department of Microbiology, Faculty of Medicine, King Abdulaziz University, Jeddah (Saudi Arabia); Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON (Canada); Van Domselaar, Gary [National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB (Canada); Li, Changgui; Wang, Junzhi [National Institute for the Control of Pharmaceutical and Biological Products, Beijing (China); She, Yi-Min; Cyr, Terry D. [Centre for Vaccine Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada, Ottawa, ON (Canada); Sui, Jianhua [Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, 44 Binney Street, Boston, MA 02115 (United States); He, Runtao [National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB (Canada); Marasco, Wayne A. [Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, 44 Binney Street, Boston, MA 02115 (United States); Li, Xuguang, E-mail: Sean.Li@hc-sc.gc.ca [Centre for Vaccine Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada, Ottawa, ON (Canada); Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON (Canada)

2010-12-10

Research highlights: {yields} The fusion peptide is the only universally conserved epitope in all influenza viral hemagglutinins. {yields} Anti-fusion peptide antibodies are universal antibodies that cross-react with all influenza HA subtypes. {yields} The universal antibodies cross-neutralize different influenza A subtypes. {yields} The universal antibodies inhibit the fusion process between the viruses and the target cells. -- Abstract: The fusion peptide of influenza viral hemagglutinin plays a critical role in virus entry by facilitating membrane fusion between the virus and target cells. As the fusion peptide is the only universally conserved epitope in all influenza A and B viruses, it could be an attractive target for vaccine-induced immune responses. We previously reported that antibodies targeting the first 14 amino acids of the N-terminus of the fusion peptide could bind to virtually all influenza virus strains and quantify hemagglutinins in vaccines produced in embryonated eggs. Here we demonstrate that these universal antibodies bind to the viral hemagglutinins in native conformation presented in infected mammalian cell cultures and neutralize multiple subtypes of virus by inhibiting the pH-dependant fusion of viral and cellular membranes. These results suggest that this unique, highly-conserved linear sequence in viral hemagglutinin is exposed sufficiently to be attacked by the antibodies during the course of infection and merits further investigation because of potential importance in the protection against diverse strains of influenza viruses.

Universal antibodies against the highly conserved influenza fusion peptide cross-neutralize several subtypes of influenza A virus

International Nuclear Information System (INIS)

Hashem, Anwar M.; Van Domselaar, Gary; Li, Changgui; Wang, Junzhi; She, Yi-Min; Cyr, Terry D.; Sui, Jianhua; He, Runtao; Marasco, Wayne A.; Li, Xuguang

2010-01-01

Research highlights: → The fusion peptide is the only universally conserved epitope in all influenza viral hemagglutinins. → Anti-fusion peptide antibodies are universal antibodies that cross-react with all influenza HA subtypes. → The universal antibodies cross-neutralize different influenza A subtypes. → The universal antibodies inhibit the fusion process between the viruses and the target cells. -- Abstract: The fusion peptide of influenza viral hemagglutinin plays a critical role in virus entry by facilitating membrane fusion between the virus and target cells. As the fusion peptide is the only universally conserved epitope in all influenza A and B viruses, it could be an attractive target for vaccine-induced immune responses. We previously reported that antibodies targeting the first 14 amino acids of the N-terminus of the fusion peptide could bind to virtually all influenza virus strains and quantify hemagglutinins in vaccines produced in embryonated eggs. Here we demonstrate that these universal antibodies bind to the viral hemagglutinins in native conformation presented in infected mammalian cell cultures and neutralize multiple subtypes of virus by inhibiting the pH-dependant fusion of viral and cellular membranes. These results suggest that this unique, highly-conserved linear sequence in viral hemagglutinin is exposed sufficiently to be attacked by the antibodies during the course of infection and merits further investigation because of potential importance in the protection against diverse strains of influenza viruses.

A xylogalacturonan epitope is specifically associated with plant cell detachment

DEFF Research Database (Denmark)

Willats, William George Tycho; McCartney, L.; Steele-King, C.G.

2004-01-01

A monoclonal antibody (LM8) was generated with specificity for xyloglacturonan (XGA) isolated from pea (Pisum sativum L.) testae. Characterization of the LM8 epitope indicates that it is a region of XGA that is highly substituted with xylose. Immunocytochemical analysis indicates that this epitop...

Monoclonal antibody proteomics: use of antibody mimotope displaying phages and the relevant synthetic peptides for mAb scouting.

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Hajdú, István; Flachner, Beáta; Bognár, Melinda; Végh, Barbara M; Dobi, Krisztina; Lőrincz, Zsolt; Lázár, József; Cseh, Sándor; Takács, László; Kurucz, István

2014-08-01

Monoclonal antibody proteomics uses nascent libraries or cloned (Plasmascan™, QuantiPlasma™) libraries of mAbs that react with individual epitopes of proteins in the human plasma. At the initial phase of library creation, cognate protein antigen and the epitope interacting with the antibodies are not known. Scouting for monoclonal antibodies (mAbs) with the best binding characteristics is of high importance for mAb based biomarker assay development. However, in the absence of the identity of the cognate antigen the task represents a challenge. We combined phage display, and surface plasmon resonance (Biacore) experiments to test whether specific phages and the respective mimotope peptides obtained from large scale studies are applicable to determine key features of antibodies for scouting. We show here that mAb captured phage-mimotope heterogeneity that is the diversity of the selected peptide sequences, is inversely correlated with an important binding descriptor; the off-rate of the antibodies and that represents clues for driving the selection of useful mAbs for biomarker assay development. Carefully chosen synthetic mimotope peptides are suitable for specificity testing in competitive assays using the target proteome, in our case the human plasma. Copyright © 2014 Elsevier B.V. All rights reserved.

Utilizing nanobody technology to target non-immunodominant domains of VAR2CSA.

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Sisse B Ditlev

Full Text Available Placental malaria is a major health problem for both pregnant women and their fetuses in malaria endemic regions. It is triggered by the accumulation of Plasmodium falciparum-infected erythrocytes (IE in the intervillous spaces of the placenta and is associated with foetal growth restriction and maternal anemia. IE accumulation is supported by the binding of the parasite-expressed protein VAR2CSA to placental chondroitin sulfate A (CSA. Defining specific CSA-binding epitopes of VAR2CSA, against which to target the immune response, is essential for the development of a vaccine aimed at blocking IE adhesion. However, the development of a VAR2CSA adhesion-blocking vaccine remains challenging due to (i the large size of VAR2CSA and (ii the extensive immune selection for polymorphisms and thereby non-neutralizing B-cell epitopes. Camelid heavy-chain-only antibodies (HcAbs are known to target epitopes that are less immunogenic to classical IgG and, due to their small size and protruding antigen-binding loop, able to reach and recognize cryptic, conformational epitopes which are inaccessible to conventional antibodies. The variable heavy chain (VHH domain is the antigen-binding site of camelid HcAbs, the so called Nanobody, which represents the smallest known (15 kDa intact, native antigen-binding fragment. In this study, we have used the Nanobody technology, an approach new to malaria research, to generate small and functional antibody fragments recognizing unique epitopes broadly distributed on VAR2CSA.

Allergen and Epitope Targets of Mouse-Specific T Cell Responses in Allergy and Asthma

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Véronique Schulten

2018-02-01

Full Text Available Mouse allergy has become increasingly common, mainly affecting laboratory workers and inner-city households. To date, only one major allergen, namely Mus m 1, has been described. We sought to identify T cell targets in mouse allergic patients. PBMC from allergic donors were expanded with either murine urine or epithelial extract and subsequently screened for cytokine production (IL-5 and IFNγ in response to overlapping peptides spanning the entire Mus m 1 sequence, peptides from various Mus m 1 isoforms [major urinary proteins (MUPs], peptides from mouse orthologs of known allergens from other mammalian species and peptides from proteins identified by immunoproteomic analysis of IgE/IgG immunoblots of mouse urine and epithelial extracts. This approach let to the identification of 106 non-redundant T cell epitopes derived from 35 antigens. Three major T cell-activating regions were defined in Mus m 1 alone. Moreover, our data show that immunodominant epitopes were largely shared between Mus m 1 and other MUPs even from different species, suggesting that sequence conservation in different allergens is a determinant for immunodominance. We further identified several novel mouse T cell antigens based on their homology to known mammalian allergens. Analysis of cohort-specific T cell responses revealed that rhinitis and asthmatic patients recognized different epitope repertoires. Epitopes defined herein can be formulated into an epitope “megapool” used to diagnose mouse allergy and study mouse-specific T cell responses directly ex vivo. This analysis of T cell epitopes provides a good basis for future studies to increase our understanding of the immunopathology associated with MO-allergy and asthma.

Studies of a murine monoclonal antibody directed against DARC: reappraisal of its specificity.

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Dorota Smolarek

Full Text Available Duffy Antigen Receptor for Chemokines (DARC plays multiple roles in human health as a blood group antigen, a receptor for chemokines and the only known receptor for Plasmodium vivax merozoites. It is the target of the murine anti-Fy6 monoclonal antibody 2C3 which binds to the first extracellular domain (ECD1, but exact nature of the recognized epitope was a subject of contradictory reports. Here, using a set of complex experiments which include expression of DARC with amino acid substitutions within the Fy6 epitope in E. coli and K562 cells, ELISA, surface plasmon resonance (SPR and flow cytometry, we have resolved discrepancies between previously published reports and show that the basic epitope recognized by 2C3 antibody is 22FEDVW26, with 22F and 26W being the most important residues. In addition, we demonstrated that 30Y plays an auxiliary role in binding, particularly when the residue is sulfated. The STD-NMR studies performed using 2C3-derived Fab and synthetic peptide corroborated most of these results, and together with the molecular modelling suggested that 25V is not involved in direct interactions with the antibody, but determines folding of the epitope backbone.

Avian Diagnostic and Therapeutic Antibodies to Viral Emerging Pathogens

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David Bradley

2011-03-31

During the current period the following key objectives were achieved: demonstration of high titer antibody production by geese following immunization with inactived H1N1 virus; completion of the epitope mapping of West Nile Virus-specific goose antibodies and initiation of epitope mapping of H1N1 flu-specific goose antibodies; advancement in scalable purification of goose antibodies.

Fully human broadly neutralizing monoclonal antibodies against influenza A viruses generated from the memory B cells of a 2009 pandemic H1N1 influenza vaccine recipient

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Hu, Weibin [Molecular Virus Unit, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200025 (China); Chen, Aizhong [Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031 (China); Miao, Yi [Shanghai Xuhui Central Hospital, Shanghai 200031 (China); Xia, Shengli [Center for Disease Control and Prevention of Henan Province, Zhengzhou 450016 (China); Ling, Zhiyang; Xu, Ke; Wang, Tongyan [Molecular Virus Unit, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200025 (China); Xu, Ying; Cui, Jun; Wu, Hongqiang; Hu, Guiyu; Tian, Lin; Wang, Lingling [Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031 (China); Shu, Yuelong [Chinese Center for Disease Control and Prevention, Beijing 102206 (China); Ma, Xiaowei [Hualan Biological Bacterin Company, Xinxiang 453003 (China); Xu, Bianli; Zhang, Jin [Center for Disease Control and Prevention of Henan Province, Zhengzhou 450016 (China); Lin, Xiaojun, E-mail: linxiaojun@hualan.com [Hualan Biological Bacterin Company, Xinxiang 453003 (China); Bian, Chao, E-mail: cbian@sibs.ac.cn [Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031 (China); Sun, Bing, E-mail: bsun@sibs.ac.cn [Molecular Virus Unit, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200025 (China); Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031 (China)

2013-01-20

Whether the 2009 pandemic H1N1 influenza vaccine can induce heterosubtypic cross-protective anti-hemagglutinin (HA) neutralizing antibodies is an important issue. We obtained a panel of fully human monoclonal antibodies from the memory B cells of a 2009 pandemic H1N1 influenza vaccine recipient. Most of the monoclonal antibodies targeted the HA protein but not the HA1 fragment. Among the analyzed antibodies, seven mAbs exhibited neutralizing activity against several influenza A viruses of different subtypes. The conserved linear epitope targeted by the neutralizing mAbs (FIEGGWTGMVDGWYGYHH) is part of the fusion peptide on HA2. Our work suggests that a heterosubtypic neutralizing antibody response primarily targeting the HA stem region exists in recipients of the 2009 pandemic H1N1 influenza vaccine. The HA stem region contains various conserved neutralizing epitopes with the fusion peptide as an important one. This work may aid in the design of a universal influenza A virus vaccine.

Fully human broadly neutralizing monoclonal antibodies against influenza A viruses generated from the memory B cells of a 2009 pandemic H1N1 influenza vaccine recipient

International Nuclear Information System (INIS)

Hu, Weibin; Chen, Aizhong; Miao, Yi; Xia, Shengli; Ling, Zhiyang; Xu, Ke; Wang, Tongyan; Xu, Ying; Cui, Jun; Wu, Hongqiang; Hu, Guiyu; Tian, Lin; Wang, Lingling; Shu, Yuelong; Ma, Xiaowei; Xu, Bianli; Zhang, Jin; Lin, Xiaojun; Bian, Chao; Sun, Bing

2013-01-01

Whether the 2009 pandemic H1N1 influenza vaccine can induce heterosubtypic cross-protective anti-hemagglutinin (HA) neutralizing antibodies is an important issue. We obtained a panel of fully human monoclonal antibodies from the memory B cells of a 2009 pandemic H1N1 influenza vaccine recipient. Most of the monoclonal antibodies targeted the HA protein but not the HA1 fragment. Among the analyzed antibodies, seven mAbs exhibited neutralizing activity against several influenza A viruses of different subtypes. The conserved linear epitope targeted by the neutralizing mAbs (FIEGGWTGMVDGWYGYHH) is part of the fusion peptide on HA2. Our work suggests that a heterosubtypic neutralizing antibody response primarily targeting the HA stem region exists in recipients of the 2009 pandemic H1N1 influenza vaccine. The HA stem region contains various conserved neutralizing epitopes with the fusion peptide as an important one. This work may aid in the design of a universal influenza A virus vaccine.

Nanobodies targeting norovirus capsid reveal functional epitopes and potential mechanisms of neutralization.

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Anna D Koromyslova

2017-11-01

Full Text Available Norovirus is the leading cause of gastroenteritis worldwide. Despite recent developments in norovirus propagation in cell culture, these viruses are still challenging to grow routinely. Moreover, little is known on how norovirus infects the host cells, except that histo-blood group antigens (HBGAs are important binding factors for infection and cell entry. Antibodies that bind at the HBGA pocket and block attachment to HBGAs are believed to neutralize the virus. However, additional neutralization epitopes elsewhere on the capsid likely exist and impeding the intrinsic structural dynamics of the capsid could be equally important. In the current study, we investigated a panel of Nanobodies in order to probe functional epitopes that could trigger capsid rearrangement and/ or interfere with HBGA binding interactions. The precise binding sites of six Nanobodies (Nano-4, Nano-14, Nano-26, Nano-27, Nano-32, and Nano-42 were identified using X-ray crystallography. We showed that these Nanobodies bound on the top, side, and bottom of the norovirus protruding domain. The impact of Nanobody binding on norovirus capsid morphology was analyzed using electron microscopy and dynamic light scattering. We discovered that distinct Nanobody epitopes were associated with varied changes in particle structural integrity and assembly. Interestingly, certain Nanobody-induced capsid morphological changes lead to the capsid protein degradation and viral RNA exposure. Moreover, Nanobodies employed multiple inhibition mechanisms to prevent norovirus attachment to HBGAs, which included steric obstruction (Nano-14, allosteric interference (Nano-32, and violation of normal capsid morphology (Nano-26 and Nano-85. Finally, we showed that two Nanobodies (Nano-26 and Nano-85 not only compromised capsid integrity and inhibited VLPs attachment to HBGAs, but also recognized a broad panel of norovirus genotypes with high affinities. Consequently, Nano-26 and Nano-85 have a great

Nanobodies targeting norovirus capsid reveal functional epitopes and potential mechanisms of neutralization

Science.gov (United States)

2017-01-01

Norovirus is the leading cause of gastroenteritis worldwide. Despite recent developments in norovirus propagation in cell culture, these viruses are still challenging to grow routinely. Moreover, little is known on how norovirus infects the host cells, except that histo-blood group antigens (HBGAs) are important binding factors for infection and cell entry. Antibodies that bind at the HBGA pocket and block attachment to HBGAs are believed to neutralize the virus. However, additional neutralization epitopes elsewhere on the capsid likely exist and impeding the intrinsic structural dynamics of the capsid could be equally important. In the current study, we investigated a panel of Nanobodies in order to probe functional epitopes that could trigger capsid rearrangement and/ or interfere with HBGA binding interactions. The precise binding sites of six Nanobodies (Nano-4, Nano-14, Nano-26, Nano-27, Nano-32, and Nano-42) were identified using X-ray crystallography. We showed that these Nanobodies bound on the top, side, and bottom of the norovirus protruding domain. The impact of Nanobody binding on norovirus capsid morphology was analyzed using electron microscopy and dynamic light scattering. We discovered that distinct Nanobody epitopes were associated with varied changes in particle structural integrity and assembly. Interestingly, certain Nanobody-induced capsid morphological changes lead to the capsid protein degradation and viral RNA exposure. Moreover, Nanobodies employed multiple inhibition mechanisms to prevent norovirus attachment to HBGAs, which included steric obstruction (Nano-14), allosteric interference (Nano-32), and violation of normal capsid morphology (Nano-26 and Nano-85). Finally, we showed that two Nanobodies (Nano-26 and Nano-85) not only compromised capsid integrity and inhibited VLPs attachment to HBGAs, but also recognized a broad panel of norovirus genotypes with high affinities. Consequently, Nano-26 and Nano-85 have a great potential to

Hexon and fiber of adenovirus type 14 and 55 are major targets of neutralizing antibody but only fiber-specific antibody contributes to cross-neutralizing activity.

Science.gov (United States)

Feng, Ying; Sun, Xikui; Ye, Xianmiao; Feng, Yupeng; Wang, Jinlin; Zheng, Xuehua; Liu, Xinglong; Yi, Changhua; Hao, Mingli; Wang, Qian; Li, Feng; Xu, Wei; Li, Liang; Li, Chufang; Zhou, Rong; Chen, Ling; Feng, Liqiang

2018-05-01

Re-emerging human adenoviruses type 14 (HAdV14) and 55 (HAdV55) represent two highly virulent adenoviruses. The neutralizing antibody (nAb) responses elicited by infection or immunization remain largely unknown. Herein, we generated hexon-chimeric HAdV14 viruses harboring each single or entire hexon hyper-variable-regions (HVR) from HAdV55, and determined the neutralizing epitopes of human and mouse nAbs. In human sera, hexon-targeting nAbs are type-specific and mainly recognize HVR2, 5, and 7. Fiber-targeting nAbs are only detectable in sera cross-neutralizing HAdV14 and HAdV55 and contribute substantially to cross-neutralization. Penton-binding antibodies, however, show no significant neutralizing activities. In mice immunized with HAdV14 or HAdV55, a single immunization mainly elicited hexon-specific nAbs, which recognized HAdV14 HVR1, 2, and 7 and HAdV55 HVR1 and 2, respectively. After a booster immunization, cross-neutralizing fiber-specific nAbs became detectable. These results indicated that hexon elicits type-specific nAbs whereas fiber induces cross-neutralizing nAbs to HAdV14 and HAdV55, which are of significance in vaccine development. Copyright © 2018 Elsevier Inc. All rights reserved.

Antibody or Antibody Fragments: Implications for Molecular Imaging and Targeted Therapy of Solid Tumors

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Katerina T. Xenaki

2017-10-01

Full Text Available The use of antibody-based therapeutics has proven very promising for clinical applications in cancer patients, with multiple examples of antibodies and antibody–drug conjugates successfully applied for the treatment of solid tumors and lymphomas. Given reported recurrence rates, improvements are clearly still necessary. A major factor limiting the efficacy of antibody-targeted cancer therapies may be the incomplete penetration of the antibody or antibody–drug conjugate into the tumor. Incomplete tumor penetration also affects the outcome of molecular imaging, when using such targeting agents. From the injection site until they arrive inside the tumor, targeting molecules are faced with several barriers that impact intratumoral distribution. The primary means of antibody transport inside tumors is based on diffusion. The diffusive penetration inside the tumor is influenced by both antibody properties, such as size and binding affinity, as well as tumor properties, such as microenvironment, vascularization, and targeted antigen availability. Engineering smaller antibody fragments has shown to improve the rate of tumor uptake and intratumoral distribution. However, it is often accompanied by more rapid clearance from the body and in several cases also by inherent destabilization and reduction of the binding affinity of the antibody. In this perspective, we discuss different cancer targeting approaches based on antibodies or their fragments. We carefully consider how their size and binding properties influence their intratumoral uptake and distribution, and how this may affect cancer imaging and therapy of solid tumors.

One target, different effects: a comparison of distinct therapeutic antibodies against the same targets.

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Shim, Hyunbo

2011-10-31

To date, more than 30 antibodies have been approved worldwide for therapeutic use. While the monoclonal antibody market is rapidly growing, the clinical use of therapeutic antibodies is mostly limited to treatment of cancers and immunological disorders. Moreover, antibodies against only five targets (TNF-α, HER2, CD20, EGFR, and VEGF) account for more than 80 percent of the worldwide market of therapeutic antibodies. The shortage of novel, clinically proven targets has resulted in the development of many distinct therapeutic antibodies against a small number of proven targets, based on the premise that different antibody molecules against the same target antigen have distinct biological and clinical effects from one another. For example, four antibodies against TNF-α have been approved by the FDA -- infliximab, adalimumab, golimumab, and certolizumab pegol -- with many more in clinical and preclinical development. The situation is similar for HER2, CD20, EGFR, and VEGF, each having one or more approved antibodies and many more under development. This review discusses the different binding characteristics, mechanisms of action, and biological and clinical activities of multiple monoclonal antibodies against TNF-α, HER-2, CD20, and EGFR and provides insights into the development of therapeutic antibodies.

High-throughput immuno-profiling of mamba (Dendroaspis) venom toxin epitopes using high-density peptide microarrays

DEFF Research Database (Denmark)

Engmark, Mikael; Andersen, Mikael Rørdam; Laustsen, Andreas Hougaard

2016-01-01

Snakebite envenoming is a serious condition requiring medical attention and administration of antivenom. Current antivenoms are antibody preparations obtained from the plasma of animals immunised with whole venom(s) and contain antibodies against snake venom toxins, but also against other antigens....... In order to better understand the molecular interactions between antivenom antibodies and epitopes on snake venom toxins, a high-throughput immuno-profiling study on all manually curated toxins from Dendroaspis species and selected African Naja species was performed based on custom-made high......-density peptide microarrays displaying linear toxin fragments. By detection of binding for three different antivenoms and performing an alanine scan, linear elements of epitopes and the positions important for binding were identified. A strong tendency of antivenom antibodies recognizing and binding to epitopes...

Effects of Surface Epitope Coverage on the Sensitivity of Displacement Assays that Employ Modified Nanoparticles: Using Bisphenol A as a Model Analyte

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Yang Lu

2016-08-01

Full Text Available With the ever-increasing use of nanoparticles in immunosensors, a fundamental study on the effect of epitope density is presented herein, with a small molecule epitope, on the performance of the displacement assay format in an enzyme-linked immunosorbent assay (ELISA. Thiolated bisphenol A (BPA functionalized gold nanoparticles (cysBPAv-AuNPs and specific anti-BPA antibodies are employed for this purpose. It is shown that the displacement of cysBPAv-AuNPs bound to the immobilized antibodies was influenced by both the avidity of bound cysBPAv-AuNPs and the concentration of free BPA to displace it. The importance of surface epitope density was that it changed the number of epitopes in close proximity to the antibody-binding site. This then influenced the avidity of cysBPAv-AuNPs bound to the immobilized antibody. Furthermore, the molar epitope concentration in an assay appears to affect the degree of antibody binding site saturation. Controlling surface epitope density of the functionalized nanoparticles and molar epitope concentration in an assay leads to a decrease of the concentration of free BPA required to displace the bound cysBPAv-AuNP, and hence better assay performance with regards to the D50 value and dynamic range in the displacement assay.

Disassembly and reassembly of human papillomavirus virus-like particles produces more virion-like antibody reactivity

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Zhao Qinjian

2012-02-01

Full Text Available Abstract Background Human papillomavirus (HPV vaccines based on major capsid protein L1 are licensed in over 100 countries to prevent HPV infections. The yeast-derived recombinant quadrivalent HPV L1 vaccine, GARDASIL(R, has played an important role in reducing cancer and genital warts since its introduction in 2006. The L1 proteins self-assemble into virus-like particles (VLPs. Results VLPs were subjected to post-purification disassembly and reassembly (D/R treatment during bioprocessing to improve VLP immunoreactivity and stability. The post-D/R HPV16 VLPs and their complex with H16.V5 neutralizing antibody Fab fragments were visualized by cryo electron microscopy, showing VLPs densely decorated with antibody. Along with structural improvements, post-D/R VLPs showed markedly higher antigenicity to conformational and neutralizing monoclonal antibodies (mAbs H16.V5, H16.E70 and H263.A2, whereas binding to mAbs recognizing linear epitopes (H16.J4, H16.O7, and H16.H5 was greatly reduced. Strikingly, post-D/R VLPs showed no detectable binding to H16.H5, indicating that the H16.H5 epitope is not accessible in fully assembled VLPs. An atomic homology model of the entire HPV16 VLP was generated based on previously determined high-resolution structures of bovine papillomavirus and HPV16 L1 pentameric capsomeres. Conclusions D/R treatment of HPV16 L1 VLPs produces more homogeneous VLPs with more virion-like antibody reactivity. These effects can be attributed to a combination of more complete and regular assembly of the VLPs, better folding of L1, reduced non-specific disulfide-mediated aggregation and increased stability of the VLPs. Markedly different antigenicity of HPV16 VLPs was observed upon D/R treatment with a panel of monoclonal antibodies targeting neutralization sensitive epitopes. Multiple epitope-specific assays with a panel of mAbs with different properties and epitopes are required to gain a better understanding of the immunochemical

Designing and overproducing a tandem epitope of gp350/220 that shows a potential to become an EBV vaccine

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Widodo

2018-03-01

Full Text Available Background: Epstein-Barr virus (EBV can cause cancer in people from around the world. There is no EBV vaccine available for use on a global scale. However, emerging evidence suggests that the epitope on the gp350/220 capsid protein may be developed into an EBV vaccine. Nevertheless, the production of small, single epitope is challenging of stability issues and possible alteration of peptide structure. In this study, a tandem epitope was developed consisting of three single epitopes, aimed to improve stability, antigenicity and preserve epitope structure. Materials and methods: A tandem epitope was designed using bioinformatics based on the epitope structure of the gp350/220 protein. The tandem epitope structure was analyzed using a protein folding method with Abalone software, which was further refined via YASARA force field and molecular repairing using a FoldX method. Immunogenicity was examined with Epitopia software, whereas allergen properties were tested using AlgPred. The pattern of the tandem epitope binding with anti-gp350/220 antibodies was performed using Z-dock and snugDock. The tandem epitope was then overproduced in E. coli strain BL21 as a host cell. Result: Our model demonstrated a successfully designed and overproduced tandem epitope. The tandem epitope demonstrated a similar structure compared with the epitope of whole protein gp350/220. Our epitope also demonstrated non-allergen and antigenicity properties, and possessed antibody binding patterns consistent with whole protein gp350/220. Conclusion and recommendation: These data suggest a novel tandem epitope composed of three similar epitopes demonstrates antigenicity, structure, and binding properties consistent with whole protein gp350/220. We also demonstrate successful production of the tandem epitope using E. coli strain BL21 as a host. Future in vivo experimental animal research is necessary to test the ability of this tandem epitope to stimulate antibody production

A Supercluster of Neutralizing Epitopes at the Interface of Ricin’s Enzymatic (RTA and Binding (RTB Subunits

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Amanda Y. Poon

2017-11-01

Full Text Available As part of an effort to engineer ricin antitoxins and immunotherapies, we previously produced and characterized a collection of phage-displayed, heavy chain-only antibodies (VHHs from alpacas that had been immunized with ricin antigens. In our initial screens, we identified nine VHHs directed against ricin toxin’s binding subunit (RTB, but only one, JIZ-B7, had toxin-neutralizing activity. Linking JIZ-B7 to different VHHs against ricin’s enzymatic subunit (RTA resulted in several bispecific antibodies with potent toxin-neutralizing activity in vitro and in vivo. JIZ-B7 may therefore be an integral component of a future VHH-based neutralizing agent (VNA for ricin toxin. In this study, we now localize, using competitive ELISA, JIZ-B7’s epitope to a region of RTB’s domain 2 sandwiched between the high-affinity galactose/N-acetylgalactosamine (Gal/GalNAc-binding site and the boundary of a neutralizing hotspot on RTA known as cluster II. Analysis of additional RTB (n = 8- and holotoxin (n = 4-specific VHHs from a recent series of screens identified a “supercluster” of neutralizing epitopes at the RTA-RTB interface. Among the VHHs tested, toxin-neutralizing activity was most closely associated with epitope proximity to RTA, and not interference with RTB’s ability to engage Gal/GalNAc receptors. We conclude that JIZ-B7 is representative of a larger group of potent toxin-neutralizing antibodies, possibly including many described in the literature dating back several decades, that recognize tertiary and possibly quaternary epitopes located at the RTA-RTB interface and that target a region of vulnerability on ricin toxin.

Pro region engineering of nerve growth factor by deep mutational scanning enables a yeast platform for conformational epitope mapping of anti-NGF monoclonal antibodies.

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Medina-Cucurella, Angélica V; Zhu, Yaqi; Bowen, Scott J; Bergeron, Lisa M; Whitehead, Timothy A

2018-04-12

Nerve growth factor (NGF) plays a central role in multiple chronic pain conditions. As such, anti-NGF monoclonal antibodies (mAbs) that function by antagonizing NGF downstream signaling are leading drug candidates for non-opioid pain relief. To evaluate anti-canine NGF (cNGF) mAbs we sought a yeast surface display platform of cNGF. Both mature cNGF and pro-cNGF displayed on the yeast surface but bound conformationally sensitive mAbs at most 2.5-fold in mean fluorescence intensity above background, suggesting that cNGF was mostly misfolded. To improve the amount of folded, displayed cNGF, we used comprehensive mutagenesis, FACS, and deep sequencing to identify point mutants in the pro-region of canine NGF that properly enhance the folded protein displayed on the yeast surface. Out of 1,737 tested single point mutants in the pro region, 49 increased the amount of NGF recognized by conformationally sensitive mAbs. These gain-of-function mutations cluster around residues A-61-P-26. Gain-of-function mutants were additive, and a construct containing three mutations increased amount of folded cNGF to 23- fold above background. Using this new cNGF construct, fine conformational epitopes for tanezumab and three anti-cNGF mAbs were evaluated. The epitope revealed by the yeast experiments largely overlapped with the tanezumab epitope previously determined by X-ray crystallography. The other mAbs showed site-specific differences with tanezumab. As the number of binding epitopes of functionally neutralizing anti-NGF mAbs on NGF are limited, subtle differences in the individual interacting residues on NGF that bind each mAb contribute to the understanding of each antibody and variations in its neutralizing activity. These results demonstrate the potential of deep sequencing-guided protein engineering to improve the production of folded surface-displayed protein, and the resulting cNGF construct provides a platform to map conformational epitopes for other anti-neurotrophin m

A novel mouse monoclonal antibody targeting ErbB2 suppresses breast cancer growth

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Kawa, Seiji [Division of Oncology, Institute of Medical Science, University of Tokyo, Shirokanedai 4-6-1, Minato-ku, Tokyo 108-8639 (Japan); Matsushita, Hirohisa; Ohbayashi, Hirokazu [Department of Research and Development, Nichirei Biosciences Inc., Tokyo 104-8402 (Japan); Semba, Kentaro [Department of Life Science and Medical Bio-Science, School of Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Yamamoto, Tadashi, E-mail: tyamamot@ims.u-tokyo.ac.jp [Division of Oncology, Institute of Medical Science, University of Tokyo, Shirokanedai 4-6-1, Minato-ku, Tokyo 108-8639 (Japan)

2009-07-03

Overexpression of ErbB2 in breast cancer is associated with increased recurrence and worse prognosis. Accumulating evidences suggest that molecular targeted therapy is a promising anticancer strategy. In this study, we produced a novel anti-ErbB2 monoclonal antibody, 6G10, that recognized an epitope distinct from the trastuzumab binding site. 6G10 induced aggregation of BT474 breast cancer cells and inhibited proliferation of various breast cancer cell lines including BT474. A growth inhibition assay showed that 6G10 had EC{sub 50} values comparable to trastuzumab, indicating that the drugs have a similar level of potency. Furthermore, intraperitoneal administration of 6G10 completely inhibited the growth of xenografted tumors derived from BT474 and SK-BR-3 cells. These data suggested that 6G10 has great therapeutic potential and could be administered to patients alternatively, or synergistically, with trastuzumab.

Automated identification of complementarity determining regions (CDRs) reveals peculiar characteristics of CDRs and B cell epitopes.

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Ofran, Yanay; Schlessinger, Avner; Rost, Burkhard

2008-11-01

Exact identification of complementarity determining regions (CDRs) is crucial for understanding and manipulating antigenic interactions. One way to do this is by marking residues on the antibody that interact with B cell epitopes on the antigen. This, of course, requires identification of B cell epitopes, which could be done by marking residues on the antigen that bind to CDRs, thus requiring identification of CDRs. To circumvent this vicious circle, existing tools for identifying CDRs are based on sequence analysis or general biophysical principles. Often, these tools, which are based on partial data, fail to agree on the boundaries of the CDRs. Herein we present an automated procedure for identifying CDRs and B cell epitopes using consensus structural regions that interact with the antigens in all known antibody-protein complexes. Consequently, we provide the first comprehensive analysis of all CDR-epitope complexes of known three-dimensional structure. The CDRs we identify only partially overlap with the regions suggested by existing methods. We found that the general physicochemical properties of both CDRs and B cell epitopes are rather peculiar. In particular, only four amino acids account for most of the sequence of CDRs, and several types of amino acids almost never appear in them. The secondary structure content and the conservation of B cell epitopes are found to be different than previously thought. These characteristics of CDRs and epitopes may be instrumental in choosing which residues to mutate in experimental search for epitopes. They may also assist in computational design of antibodies and in predicting B cell epitopes.

Quaternary epitopes of α345(IV) collagen initiate Alport post-transplant anti-GBM nephritis

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Olaru, Florina; Luo, Wentian; Wang, Xu-Ping

2013-01-01

Alport post-transplant nephritis (APTN) is an aggressive form of anti-glomerular basement membrane disease that targets the allograft in transplanted patients with X-linked Alport syndrome. Alloantibodies develop against the NC1 domain of α5(IV) collagen, which occurs in normal kidneys, including...... of alloantibodies against allogeneic collagen IV. Some alloantibodies targeted alloepitopes within α5NC1 monomers, shared by α345NC1 and α1256NC1 hexamers. Other alloantibodies specifically targeted alloepitopes that depended on the quaternary structure of α345NC1 hexamers. In Col4a5-null mice, immunization...... with native forms of allogeneic collagen IV exclusively elicited antibodies to quaternary α345NC1 alloepitopes, whereas alloimmunogens lacking native quaternary structure elicited antibodies to shared α5NC1 alloepitopes. These results imply that quaternary epitopes within α345NC1 hexamers may initiate...

Characterization of two conformational epitopes of the Chlamydia trachomatis serovar L2 DnaK immunogen

DEFF Research Database (Denmark)

Birkelund, Svend; Mygind, P; Holm, A

1996-01-01

this protein. By use of recombinant DNA techniques, we located the epitopes for two MAbs in the C-terminal variable part. Although the antibodies reacted in an immunoblot assay, it was not possible to map the epitopes completely by use of 16-mer synthetic peptides displaced by one amino acid corresponding......Chlamydia trachomatis DnaK is an important immunogen in chlamydial infections. DnaK is composed of a conserved N-terminal ATP-binding domain and a variable C-terminal peptide-binding domain. To locate the immunogenic part of C. trachomatis Dnak, we generated monoclonal antibodies (MAbs) against...... with the two antibodies. The epitopes were found not to overlap. To obtain DnaK fragments recognized by the antibodies with the same affinity as native C. trachomatis DnaK, it was necessary to express, respectively, regions of 127 and 77 amino acids. The MAbs described in this study thus recognized...

Superior control of HIV-1 replication by CD8+ T cells targeting conserved epitopes: implications for HIV vaccine design.

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Pratima Kunwar

Full Text Available A successful HIV vaccine will likely induce both humoral and cell-mediated immunity, however, the enormous diversity of HIV has hampered the development of a vaccine that effectively elicits both arms of the adaptive immune response. To tackle the problem of viral diversity, T cell-based vaccine approaches have focused on two main strategies (i increasing the breadth of vaccine-induced responses or (ii increasing vaccine-induced responses targeting only conserved regions of the virus. The relative extent to which set-point viremia is impacted by epitope-conservation of CD8(+ T cell responses elicited during early HIV-infection is unknown but has important implications for vaccine design. To address this question, we comprehensively mapped HIV-1 CD8(+ T cell epitope-specificities in 23 ART-naïve individuals during early infection and computed their conservation score (CS by three different methods (prevalence, entropy and conseq on clade-B and group-M sequence alignments. The majority of CD8(+ T cell responses were directed against variable epitopes (p<0.01. Interestingly, increasing breadth of CD8(+ T cell responses specifically recognizing conserved epitopes was associated with lower set-point viremia (r = - 0.65, p = 0.009. Moreover, subjects possessing CD8(+ T cells recognizing at least one conserved epitope had 1.4 log10 lower set-point viremia compared to those recognizing only variable epitopes (p = 0.021. The association between viral control and the breadth of conserved CD8(+ T cell responses may be influenced by the method of CS definition and sequences used to determine conservation levels. Strikingly, targeting variable versus conserved epitopes was independent of HLA type (p = 0.215. The associations with viral control were independent of functional avidity of CD8(+ T cell responses elicited during early infection. Taken together, these data suggest that the next-generation of T-cell based HIV-1 vaccines should focus

Structural delineation of a quaternary, cleavage-dependent epitope at the gp41-gp120 interface on intact HIV-1 Env trimers.

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Blattner, Claudia; Lee, Jeong Hyun; Sliepen, Kwinten; Derking, Ronald; Falkowska, Emilia; de la Peña, Alba Torrents; Cupo, Albert; Julien, Jean-Philippe; van Gils, Marit; Lee, Peter S; Peng, Wenjie; Paulson, James C; Poignard, Pascal; Burton, Dennis R; Moore, John P; Sanders, Rogier W; Wilson, Ian A; Ward, Andrew B

2014-05-15

All previously characterized broadly neutralizing antibodies to the HIV-1 envelope glycoprotein (Env) target one of four major sites of vulnerability. Here, we define and structurally characterize a unique epitope on Env that is recognized by a recently discovered family of human monoclonal antibodies (PGT151-PGT158). The PGT151 epitope is comprised of residues and glycans at the interface of gp41 and gp120 within a single protomer and glycans from both subunits of a second protomer and represents a neutralizing epitope that is dependent on both gp120 and gp41. Because PGT151 binds only to properly formed, cleaved trimers, this distinctive property, and its ability to stabilize Env trimers, has enabled the successful purification of mature, cleaved Env trimers from the cell surface as a complex with PGT151. Here we compare the structural and functional properties of membrane-extracted Env trimers from several clades with those of the soluble, cleaved SOSIP gp140 trimer. Copyright © 2014 Elsevier Inc. All rights reserved.

Generation of human scFvs antibodies recognizing a prion protein epitope expressed on the surface of human lymphoblastoid cells

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Imperiale Valentina

2007-07-01

Full Text Available Abstract Background A hallmark of prion disease is the transformation of normal cellular prion protein (PrPc into an infectious disease-associated isoform, (PrPsc. Anti-prion protein monoclonal antibodies are invaluable for structure-function studies of PrP molecules. Furthermore recent in vitro and in vivo studies indicate that anti-PrP monoclonal antibodies can prevent the incorporation of PrPc into propagating prions. In the present article, we show two new human phage antibodies, isolated on recombinant hamster prion protein (rHaPrP. Results We adopted an antibody phage display strategy to isolate specific human antibodies directed towards rHaPrP which has been used as a bait for panning the synthetic ETH-2 antibody phage library. Two phage antibodies clones named MA3.B4 and MA3.G3 were isolated and characterized under genetic biochemical and immunocytochemical aspects. The clones were found to recognize the prion protein in ELISA studies. In flow-cytometry studies, these human single chain Fragment variable (scFv phage-antibodies show a well defined pattern of reactivity on human lymphoblastoid and myeloid cells. Conclusion Sequence analysis of the gene encoding for the antibody fragments and antigen recognition patterns determined by flow-cytometry analysis indicate that the isolated scFvs recognize novel epitopes in the PrPc molecule. These new anti PrPc human antibodies are unique reagents for prion protein detection and may represent a biologic platform to develop new reagents to treat PrPsc associated disease.

Identification and characterization of two linear epitope motifs in hepatitis E virus ORF2 protein.

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Heng Wang

Full Text Available Hepatitis E virus (HEV is responsible for hepatitis E, which represents a global public health problem. HEV genotypes 3 and 4 are reported to be zoonotic, and animals are monitored for HEV infection in the interests of public hygiene and food safety. The development of novel diagnostic methods and vaccines for HEV in humans is thus important topics of research. Opening reading frame (ORF 2 of HEV includes both linear and conformational epitopes and is regarded as the primary candidate for vaccines and diagnostic tests. We investigated the precise location of the HEV epitopes in the ORF2 protein. We prepared four monoclonal antibodies (mAbs against genotype 4 ORF2 protein and identified two linear epitopes, G438IVIPHD444 and Y457DNQH461, corresponding to two of these mAbs using phage display biopanning technology. Both these epitopes were speculated to be universal to genotypes 1, 2, 3, 4, and avian HEVs. We also used two 12-mer fragments of ORF2 protein including these two epitopes to develop a peptide-based enzyme-linked immunosorbent assay (ELISA to detect HEV in serum. This assay demonstrated good specificity but low sensitivity compared with the commercial method, indicating that these two epitopes could serve as potential candidate targets for diagnosis. Overall, these results further our understanding of the epitope distribution of HEV ORF2, and provide important information for the development of peptide-based immunodiagnostic tests to detect HEV in serum.

Characterization of an immunodominant cancer-specific O-glycopeptide epitope in murine podoplanin (OTS8)

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Steentoft, Catharina; Schjoldager, Katrine T; Cló, Emiliano

2010-01-01

antibody 237, developed to a spontaneous murine fibrosarcoma, was shown to be directed to murine podoplanin (OTS8) with truncated Tn O-glycans. Our understanding of such cancer-specific auto-antibodies to truncated glycoforms of glycoproteins is limited. Here we have investigated immunogenicity...... of a chemoenzymatically produced Tn-glycopeptide derived from the putative murine podoplanin O-glycopeptide epitope. We found that the Tn O-glycopeptide was highly immunogenic in mice and produced a Tn-glycoform specific response with no reactivity against unglycosylated peptides or the O-glycopeptide with extended O......-glycan (STn and T glycoforms). The immunodominant epitope was strictly dependent on the peptide sequence, required Tn at a specific single Thr residue (Thr(77)), and antibodies to the epitope were not found in naive mice. We further tested a Tn O-glycopeptide library derived from human podoplanin...

Epitope mapping of functional domains of human factor V with human and mouse monoclonal antibodies

International Nuclear Information System (INIS)

Annamalai, A.E.; Rao, A.K.; Chiu, H.C.; Wang, D.; Dutta-Roy, A.K.; Colman, R.W.

1986-01-01

The authors previously described two human monoclonal antibodies (MAbs) which inactivated factor V. The authors have now purified the predominant antibody (H2) on protein A Sepharose using a pH gradient and typed it as IgG 1 ,. Immunoprecipitation of 125 I-human factor Va with H2 demonstrated specificity for the heavy chain (D), Mr = 105,000. The authors compared using ELISA the competitive binding to factor Va, of H2, H1 and two mouse MAbs, B38 (directed to E) and B10 (to activation peptide, Cl). All four antibodies recognized distinct epitopes in factor V with steric overlap in some cases. Factor Xa showed a concentration dependent competition for binding of H1, H2 and B38 but not B10 to factor V/Va in ELISA. All MAbs bound to factor V/Va in the absence of Ca ++ . However, Ca ++ at 8 mM increased the binding of H1 and H2 to 165% and 360% and did not have any effect on the binding of either mouse MAbs. Prothrombin at a concentration of up to 400 μg/ml did not inhibit binding of any of these antibodies. Thus, both the light (E) and heavy (D) chains of factor Va but not the activation peptide (Cl) interact with factor Xa as defined by the MAbs. In addition, sites on both chains for Ca ++ are recognized by particular MAbs (H1 and H2). These studies increase their knowledge of the interactions of factor V domains in the formation of prothrombinase complex

Structure-based, targeted deglycosylation of HIV-1 gp120 and effects on neutralization sensitivity and antibody recognition

International Nuclear Information System (INIS)

Koch, Markus; Pancera, Marie; Kwong, Peter D.; Kolchinsky, Peter; Grundner, Christoph; Wang Liping; Hendrickson, Wayne A.; Sodroski, Joseph; Wyatt, Richard

2003-01-01

The human immunodeficiency virus (HIV-1) exterior envelope glycoprotein, gp120, mediates receptor binding and is the major target for neutralizing antibodies. Primary HIV-1 isolates are characteristically more resistant to broadly neutralizing antibodies, although the structural basis for this resistance remains obscure. Most broadly neutralizing antibodies are directed against functionally conserved gp120 regions involved in binding to either the primary virus receptor, CD4, or the viral coreceptor molecules that normally function as chemokine receptors. These antibodies are known as CD4 binding site (CD4BS) and CD4-induced (CD4i) antibodies, respectively. Inspection of the gp120 crystal structure reveals that although the receptor-binding regions lack glycosylation, sugar moieties lie proximal to both receptor-binding sites on gp120 and thus in proximity to both the CD4BS and the CD4i epitopes. In this study, guided by the X-ray crystal structure of gp120, we deleted four N-linked glycosylation sites that flank the receptor-binding regions. We examined the effects of selected changes on the sensitivity of two prototypic HIV-1 primary isolates to neutralization by antibodies. Surprisingly, removal of a single N-linked glycosylation site at the base of the gp120 third variable region (V3 loop) increased the sensitivity of the primary viruses to neutralization by CD4BS antibodies. Envelope glycoprotein oligomers on the cell surface derived from the V3 glycan-deficient virus were better recognized by a CD4BS antibody and a V3 loop antibody than were the wild-type glycoproteins. Absence of all four glycosylation sites rendered a primary isolate sensitive to CD4i antibody-mediated neutralization. Thus, carbohydrates that flank receptor-binding regions on gp120 protect primary HIV-1 isolates from antibody-mediated neutralization

Monoclonal antibodies for radioimmunodetection of tumours and for targeting

International Nuclear Information System (INIS)

Baldwin, R.W.; Embleton, M.J.; Pimm, M.V.

1983-01-01

A monoclonal antibody 791T/36 prepared against human osteogenic sarcoma has been used to detect primary and metastatic colorectal carcinomas by external imaging of patients following injection of 131 I-labelled antibody. In 10 of 11 patients radiolabelled 791T/36 antibody localized in tumours, the tumour/non tumour ratio of radioactivity ranging from 1.5:1 to 8.1. 791T/36 antibody was also evaluated for its potential for targeting anti-tumour agents including cytotoxic drugs (Vindesine) and immunomodulating agents (interferon). Vindesine-791T/36 conjugates were preferentially cytotoxic in vitro for target cells expressing the 791T/36 anti-body defined antigen. Also interferon conjugated to 791T/36 antibody, like free interferon activated peripheral blood natural killer cell activity. These in vitro tests together with related studies on antibody localization in vivo indicate the potential of monoclonal antibody targeting of anti-tumour agents

Identification of conformational epitopes for human IgG on Chemotaxis inhibitory protein of Staphylococcus aureus

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Furebring Christina

2009-03-01

Full Text Available Abstract Background The Chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS blocks the Complement fragment C5a receptor (C5aR and formylated peptide receptor (FPR and is thereby a potent inhibitor of neutrophil chemotaxis and activation of inflammatory responses. The majority of the healthy human population has antibodies against CHIPS that have been shown to interfere with its function in vitro. The aim of this study was to define potential epitopes for human antibodies on the CHIPS surface. We also initiate the process to identify a mutated CHIPS molecule that is not efficiently recognized by preformed anti-CHIPS antibodies and retains anti-inflammatory activity. Results In this paper, we panned peptide displaying phage libraries against a pool of CHIPS specific affinity-purified polyclonal human IgG. The selected peptides could be divided into two groups of sequences. The first group was the most dominant with 36 of the 48 sequenced clones represented. Binding to human affinity-purified IgG was verified by ELISA for a selection of peptide sequences in phage format. For further analysis, one peptide was chemically synthesized and antibodies affinity-purified on this peptide were found to bind the CHIPS molecule as studied by ELISA and Surface Plasmon Resonance. Furthermore, seven potential conformational epitopes responsible for antibody recognition were identified by mapping phage selected peptide sequences on the CHIPS surface as defined in the NMR structure of the recombinant CHIPS31–121 protein. Mapped epitopes were verified by in vitro mutational analysis of the CHIPS molecule. Single mutations introduced in the proposed antibody epitopes were shown to decrease antibody binding to CHIPS. The biological function in terms of C5aR signaling was studied by flow cytometry. A few mutations were shown to affect this biological function as well as the antibody binding. Conclusion Conformational epitopes recognized by human antibodies

Immune recognition surface construction of Mycobacterium tuberculosis epitope-specific antibody responses in tuberculosis patients identified by peptide microarrays

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Davide Valentini

2017-03-01

Conclusions: These data reveal the heterogeneity of epitope-dependent humoral immune responses in TB patients, partly due to geographical setting. These findings expose a new avenue for mining clinically meaningful vaccine targets, diagnostic tools, and the development of immunotherapeutics in TB disease management or prevention.

Structural basis for the antibody neutralization of Herpes simplex virus

Energy Technology Data Exchange (ETDEWEB)

Lee, Cheng-Chung; Lin, Li-Ling [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Chan, Woan-Eng [Development Center for Biotechnology, New Taipei City 221, Taiwan (China); Ko, Tzu-Ping [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Lai, Jiann-Shiun [Development Center for Biotechnology, New Taipei City 221, Taiwan (China); Ministry of Economic Affairs, Taipei 100, Taiwan (China); Wang, Andrew H.-J., E-mail: ahjwang@gate.sinica.edu.tw [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Taipei Medical University, Taipei 110, Taiwan (China)

2013-10-01

The gD–E317-Fab complex crystal revealed the conformational epitope of human mAb E317 on HSV gD, providing a molecular basis for understanding the viral neutralization mechanism. Glycoprotein D (gD) of Herpes simplex virus (HSV) binds to a host cell surface receptor, which is required to trigger membrane fusion for virion entry into the host cell. gD has become a validated anti-HSV target for therapeutic antibody development. The highly inhibitory human monoclonal antibody E317 (mAb E317) was previously raised against HSV gD for viral neutralization. To understand the structural basis of antibody neutralization, crystals of the gD ectodomain bound to the E317 Fab domain were obtained. The structure of the complex reveals that E317 interacts with gD mainly through the heavy chain, which covers a large area for epitope recognition on gD, with a flexible N-terminal and C-terminal conformation. The epitope core structure maps to the external surface of gD, corresponding to the binding sites of two receptors, herpesvirus entry mediator (HVEM) and nectin-1, which mediate HSV infection. E317 directly recognizes the gD–nectin-1 interface and occludes the HVEM contact site of gD to block its binding to either receptor. The binding of E317 to gD also prohibits the formation of the N-terminal hairpin of gD for HVEM recognition. The major E317-binding site on gD overlaps with either the nectin-1-binding residues or the neutralizing antigenic sites identified thus far (Tyr38, Asp215, Arg222 and Phe223). The epitopes of gD for E317 binding are highly conserved between two types of human herpesvirus (HSV-1 and HSV-2). This study enables the virus-neutralizing epitopes to be correlated with the receptor-binding regions. The results further strengthen the previously demonstrated therapeutic and diagnostic potential of the E317 antibody.

AL amyloid imaging and therapy with a monoclonal antibody to a cryptic epitope on amyloid fibrils.

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Jonathan S Wall

Full Text Available The monoclonal antibody 2A4 binds an epitope derived from a cleavage site of serum amyloid protein A (sAA containing a -Glu-Asp- amino acid pairing. In addition to its reactivity with sAA amyloid deposits, the antibody was also found to bind amyloid fibrils composed of immunoglobulin light chains. The antibody binds to synthetic fibrils and human light chain (AL amyloid extracts with high affinity even in the presence of soluble light chain proteins. Immunohistochemistry with biotinylated 2A4 demonstrated positive reaction with ALκ and ALλ human amyloid deposits in various organs. Surface plasmon resonance analyses using synthetic AL fibrils as a substrate revealed that 2A4 bound with a K(D of ∼10 nM. Binding was inhibited in the presence of the -Glu-Asp- containing immunogen peptide. Radiolabeled 2A4 specifically localized with human AL amyloid extracts implanted in mice (amyloidomas as evidenced by single photon emission (SPECT imaging. Furthermore, co-localization of the radiolabeled mAb with amyloid was shown in biodistribution and micro-autoradiography studies. Treatment with 2A4 expedited regression of ALκ amyloidomas in mice, likely mediated by the action of macrophages and neutrophils, relative to animals that received a control antibody. These data indicate that the 2A4 mAb might be of interest for potential imaging and immunotherapy in patients with AL amyloidosis.

Antigen-targeting strategies using single-domain antibody fragments

NARCIS (Netherlands)

Duarte, Joao Nuno Silva

2017-01-01

Antibodies display high selectivity and affinity and have been the preferred platform for antigen targeting. Despite the development of antigen-delivery systems that enable T cell activation, targeting approaches that enhance antibody responses need improvement. This need specially applies to poorly

Antibody phage display applications for nuclear medicine imaging and therapy

International Nuclear Information System (INIS)

Winthrop, M.D.; Denardo, G.L.; Denardo, S.J.

2000-01-01

Antibody-based constructs genetically engineered from genes of diverse origin provide a remarkable opportunity to develop functional molecular imaging techniques and specific molecular targeted radionuclide therapies. Phage display libraries of antibody fragment genes can be used to select antibody-based constructs that bind any chosen epitope. A large naive human antibody-based library was used to illustrate binding of antibody constructs to a variety of common and unique antigens. Antibody-based libraries from hybridoma cells, lymphocytes from immunized humans or from mice and human antibody repertoires produced in transgenic mice have also been described. Several orders of magnitude of affinity enhancement can be achieved by random or site specific mutations of the selected binding peptide domains of the scFv. Affinities (K d ) as high as 10 - 11 M (10 pM) for affinity-matured scFv have been documented. Such gene libraries thus offer an almost limitless variety of antibody-based molecular binding peptide modules that can be used in creative ways for the construction of new targeting agents for functional or molecular imaging and therapy

Three monoclonal antibodies against the serpin protease nexin-1 prevent protease translocation

DEFF Research Database (Denmark)

Kousted, Tina Mostrup; Skjoedt, K; Petersen, S V

2013-01-01

abolish the protease inhibitory activity of PN-1. In the presence of the antibodies, PN-1 does not form a complex with its target proteases, but is recovered in a reactive centre cleaved form. Using site-directed mutagenesis, we mapped the three overlapping epitopes to an area spanning the gap between...

Antibody-mediated neutralization of Ebola virus can occur by two distinct mechanisms

International Nuclear Information System (INIS)

Shedlock, Devon J.; Bailey, Michael A.; Popernack, Paul M.; Cunningham, James M.; Burton, Dennis R.; Sullivan, Nancy J.

2010-01-01

Human Ebola virus causes severe hemorrhagic fever disease with high mortality and there is no vaccine or treatment. Antibodies in survivors occur early, are sustained, and can delay infection when transferred into nonhuman primates. Monoclonal antibodies (mAbs) from survivors exhibit potent neutralizing activity in vitro and are protective in rodents. To better understand targets and mechanisms of neutralization, we investigated a panel of mAbs shown previously to react with the envelope glycoprotein (GP). While one non-neutralizing mAb recognized a GP epitope in the nonessential mucin-like domain, the rest were specific for GP1, were neutralizing, and could be further distinguished by reactivity with secreted GP. We show that survivor antibodies, human KZ52 and monkey JP3K11, were specific for conformation-dependent epitopes comprising residues in GP1 and GP2 and that neutralization occurred by two distinct mechanisms; KZ52 inhibited cathepsin cleavage of GP whereas JP3K11 recognized the cleaved, fusion-active form of GP.

Affinity Purification and Comparative Biosensor Analysis of Citrulline-Peptide-Specific Antibodies in Rheumatoid Arthritis

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Eszter Szarka

2018-01-01

Full Text Available Background: In rheumatoid arthritis (RA, anti-citrullinated protein/peptide antibodies (ACPAs are responsible for disease onset and progression, however, our knowledge is limited on ligand binding affinities of autoantibodies with different citrulline-peptide specificity. Methods: Citrulline-peptide-specific ACPA IgGs were affinity purified and tested by ELISA. Binding affinities of ACPA IgGs and serum antibodies were compared by surface plasmon resonance (SPR analysis. Bifunctional nanoparticles harboring a multi-epitope citrulline-peptide and a complement-activating peptide were used to induce selective depletion of ACPA-producing B cells. Results: KD values of affinity-purified ACPA IgGs varied between 10−6 and 10−8 M and inversely correlated with disease activity. Based on their cross-reaction with citrulline-peptides, we designed a novel multi-epitope peptide, containing Cit-Gly and Ala-Cit motifs in two–two copies, separated with a short, neutral spacer. This peptide detected antibodies in RA sera with 66% sensitivity and 98% specificity in ELISA and was recognized by 90% of RA sera, while none of the healthy samples in SPR. When coupled to nanoparticles, the multi-epitope peptide specifically targeted and depleted ACPA-producing B cells ex vivo. Conclusions: The unique multi-epitope peptide designed based on ACPA cross-reactivity might be suitable to develop better diagnostics and novel therapies for RA.

Thermodynamic Mechanism for the Evasion of Antibody Neutralization in Flaviviruses

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2015-01-01

Mutations in the epitopes of antigenic proteins can confer viral resistance to antibody-mediated neutralization. However, the fundamental properties that characterize epitope residues and how mutations affect antibody binding to alter virus susceptibility to neutralization remain largely unknown. To address these questions, we used an ensemble-based algorithm to characterize the effects of mutations on the thermodynamics of protein conformational fluctuations. We applied this method to the envelope protein domain III (ED3) of two medically important flaviviruses: West Nile and dengue 2. We determined an intimate relationship between the susceptibility of a residue to thermodynamic perturbations and epitope location. This relationship allows the successful identification of the primary epitopes in each ED3, despite their high sequence and structural similarity. Mutations that allow the ED3 to evade detection by the antibody either increase or decrease conformational fluctuations of the epitopes through local effects or long-range interactions. Spatially distant interactions originate in the redistribution of conformations of the ED3 ensembles, not through a mechanically connected array of contiguous amino acids. These results reconcile previous observations of evasion of neutralization by mutations at a distance from the epitopes. Finally, we established a quantitative correlation between subtle changes in the conformational fluctuations of the epitope and large defects in antibody binding affinity. This correlation suggests that mutations that allow viral growth, while reducing neutralization, do not generate significant structural changes and underscores the importance of protein fluctuations and long-range interactions in the mechanism of antibody-mediated neutralization resistance. PMID:24950171

A novel multi-variant epitope ensemble vaccine against avian leukosis virus subgroup J.

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Wang, Xiaoyu; Zhou, Defang; Wang, Guihua; Huang, Libo; Zheng, Qiankun; Li, Chengui; Cheng, Ziqiang

2017-12-04

The hypervariable antigenicity and immunosuppressive features of avian leukosis virus subgroup J (ALV-J) has led to great challenges to develop effective vaccines. Epitope vaccine will be a perspective trend. Previously, we identified a variant antigenic neutralizing epitope in hypervariable region 1 (hr1) of ALV-J, N-LRDFIA/E/TKWKS/GDDL/HLIRPYVNQS-C. BLAST analysis showed that the mutation of A, E, T and H in this epitope cover 79% of all ALV-J strains. Base on this data, we designed a multi-variant epitope ensemble vaccine comprising the four mutation variants linked with glycine and serine. The recombinant multi-variant epitope gene was expressed in Escherichia coli BL21. The expressed protein of the variant multi-variant epitope gene can react with positive sera and monoclonal antibodies of ALV-J, while cannot react with ALV-J negative sera. The multi-variant epitope vaccine that conjugated Freund's adjuvant complete/incomplete showed high immunogenicity that reached the titer of 1:64,000 at 42 days post immunization and maintained the immune period for at least 126 days in SPF chickens. Further, we demonstrated that the antibody induced by the variant multi-variant ensemble epitope vaccine recognized and neutralized different ALV-J strains (NX0101, TA1, WS1, BZ1224 and BZ4). Protection experiment that was evaluated by clinical symptom, viral shedding, weight gain, gross and histopathology showed 100% chickens that inoculated the multi-epitope vaccine were well protected against ALV-J challenge. The result shows a promising multi-variant epitope ensemble vaccine against hypervariable viruses in animals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Antigenic properties of the human immunodeficiency virus envelope glycoprotein gp120 on virions bound to target cells.

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Meron Mengistu

2015-03-01

Full Text Available The HIV-1 envelope glycoprotein, gp120, undergoes multiple molecular interactions and structural rearrangements during the course of host cell attachment and viral entry, which are being increasingly defined at the atomic level using isolated proteins. In comparison, antigenic markers of these dynamic changes are essentially unknown for single HIV-1 particles bound to target cells. Such markers should indicate how neutralizing and/or non-neutralizing antibodies might interdict infection by either blocking infection or sensitizing host cells for elimination by Fc-mediated effector function. Here we address this deficit by imaging fluorescently labeled CCR5-tropic HIV-1 pseudoviruses using confocal and superresolution microscopy to track the exposure of neutralizing and non-neutralizing epitopes as they appear on single HIV-1 particles bound to target cells. Epitope exposure was followed under conditions permissive or non-permissive for viral entry to delimit changes associated with virion binding from those associated with post-attachment events. We find that a previously unexpected array of gp120 epitopes is exposed rapidly upon target cell binding. This array comprises both neutralizing and non-neutralizing epitopes, the latter being hidden on free virions yet capable of serving as potent targets for Fc-mediated effector function. Under non-permissive conditions for viral entry, both neutralizing and non-neutralizing epitope exposures were relatively static over time for the majority of bound virions. Under entry-permissive conditions, epitope exposure patterns changed over time on subsets of virions that exhibited concurrent variations in virion contents. These studies reveal that bound virions are distinguished by a broad array of both neutralizing and non-neutralizing gp120 epitopes that potentially sensitize a freshly engaged target cell for destruction by Fc-mediated effector function and/or for direct neutralization at a post-binding step

Structure and Recognition of a Novel HIV-1 gp120-gp41 Interface Antibody that Caused MPER Exposure through Viral Escape

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Wibmer, Constantinos Kurt; Gorman, Jason; Ozorowski, Gabriel; Bhiman, Jinal N.; Sheward, Daniel J.; Elliott, Debra H.; Rouelle, Julie; Smira, Ashley; Joyce, M. Gordon; Ndabambi, Nonkululeko; Druz, Aliaksandr; Asokan, Mangai; Burton, Dennis R.; Connors, Mark; Abdool Karim, Salim S.; Mascola, John R.; Robinson, James E.; Ward, Andrew B.; Williamson, Carolyn; Kwong, Peter D.; Morris, Lynn; Moore, Penny L.; Desrosiers, Ronald C.

2017-01-11

A comprehensive understanding of the regions on HIV-1 envelope trimers targeted by broadly neutralizing antibodies may contribute to rational design of an HIV-1 vaccine. We previously identified a participant in the CAPRISA cohort, CAP248, who developed trimer-specific antibodies capable of neutralizing 60% of heterologous viruses at three years post-infection. Here, we report the isolation by B cell culture of monoclonal antibody CAP248-2B, which targets a novel membrane proximal epitope including elements of gp120 and gp41. Despite low maximum inhibition plateaus, often below 50% inhibitory concentrations, the breadth of CAP248-2B significantly correlated with donor plasma. Site-directed mutagenesis, X-ray crystallography, and negative-stain electron microscopy 3D reconstructions revealed how CAP248-2B recognizes a cleavage-dependent epitope that includes the gp120 C terminus. While this epitope is distinct, it overlapped in parts of gp41 with the epitopes of broadly neutralizing antibodies PGT151, VRC34, 35O22, 3BC315, and 10E8. CAP248-2B has a conformationally variable paratope with an unusually long 19 amino acid light chain third complementarity determining region. Two phenylalanines at the loop apex were predicted by docking and mutagenesis data to interact with the viral membrane. Neutralization by CAP248-2B is not dependent on any single glycan proximal to its epitope, and low neutralization plateaus could not be completely explained by N- or O-linked glycosylation pathway inhibitors, furin co-transfection, or pre-incubation with soluble CD4. Viral escape from CAP248-2B involved a cluster of rare mutations in the gp120-gp41 cleavage sites. Simultaneous introduction of these mutations into heterologous viruses abrogated neutralization by CAP248-2B, but enhanced neutralization sensitivity to 35O22, 4E10, and 10E8 by 10-100-fold. Altogether, this study expands the region of the HIV-1 gp120-gp41 quaternary interface that is a target for broadly neutralizing

Addressing the Immunogenicity of the Cargo and of the Targeting Antibodies with a Focus on Deimmunized Bacterial Toxins and on Antibody-Targeted Human Effector Proteins

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Grinberg, Yehudit; Benhar, Itai

2017-01-01

Third-generation immunotoxins are composed of a human, or humanized, targeting moiety, usually a monoclonal antibody or an antibody fragment, and a non-human effector molecule. Due to the non-human origin of the cytotoxic domain, these molecules stimulate potent anti-drug immune responses, which limit treatment options. Efforts are made to deimmunize such immunotoxins or to combine treatment with immunosuppression. An alternative approach is using the so-called “human cytotoxic fusion proteins”, in which antibodies are used to target human effector proteins. Here, we present three relevant approaches for reducing the immunogenicity of antibody-targeted protein therapeutics: (1) reducing the immunogenicity of the bacterial toxin, (2) fusing human cytokines to antibodies to generate immunocytokines and (3) addressing the immunogenicity of the targeting antibodies. PMID:28574434

Identification and characterization of a virus-specific continuous B-cell epitope on the PrM/M protein of Japanese Encephalitis Virus: potential application in the detection of antibodies to distinguish Japanese Encephalitis Virus infection from West Nile Virus and Dengue Virus infections

OpenAIRE

Hua, Rong-Hong; Chen, Na-Sha; Qin, Cheng-Feng; Deng, Yong-Qiang; Ge, Jin-Ying; Wang, Xi-Jun; Qiao, Zu-Jian; Chen, Wei-Ye; Wen, Zhi-Yuan; Liu, Wen-Xin; Hu, Sen; Bu, Zhi-Gao

2010-01-01

Abstract Background Differential diagnose of Japanese encephalitis virus (JEV) infection from other flavivirus especially West Nile virus (WNV) and Dengue virus (DV) infection was greatly hindered for the serological cross-reactive. Virus specific epitopes could benefit for developing JEV specific antibodies detection methods. To identify the JEV specific epitopes, we fully mapped and characterized the continuous B-cell epitope of the PrM/M protein of JEV. Results To map the epitopes on the P...

Characterization of an extracellular epitope antibody to the neuronal K-Cl cotransporter, KCC2.

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Gagnon, Kenneth Be; Fyffe, Robert Ew; Adragna, Norma C; Lauf, Peter K

2007-07-01

1. Ion gradients across the cell membrane are important for proper cellular communication and homeostasis. With the exception of erythrocytes, chloride (Cl), one of the most important free anions in animal cells, is not distributed at thermodynamic equilibrium across the plasma membrane. The K-Cl cotransporter (COT), consisting of at least four isoforms, utilizes the larger outwardly directed chemical driving force of K to expel Cl from the cell against its inwardly directed chemical gradient and has been implicated recently as one of the main Cl extruders in developing neurons. 2. Previous in situ hybridization studies have indicated widespread mRNA distribution of the neuronal-specific K-Cl COT isoform (KCC2) throughout the rat central nervous system (CNS). However, immunohistochemical studies have been limited owing to the availability of a more selective antibody to KCC2. The goal of the present study was to develop a new molecular tool for the immunohistochemical identification and neuronal distribution of KCC2. 3. Herein, we present evidence of immunohistochemical corroboration of the widespread KCC2 mRNA expression using a novel extracellular anti-peptide antibody directed against the second extracellular loop (ECL2) of KCC2. Immunoperoxidase and immunofluorescent labelling revealed widespread post-synaptic somatic and dendritic localization of KCC2 in multiple neuronal populations in the cerebral cortex, hippocampus, brainstem, lumbar spinal cord and cerebellum. We also demonstrate that binding of the antibody to an extracellular epitope within ECL2 does not alter cotransporter function. In essence, the present study reports on a new molecular tool for structural and functional studies of KCC2.

Thyroid Autoantibodies Display both “Original Antigenic Sin” and Epitope Spreading

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Sandra M. McLachlan

2017-12-01

Full Text Available Evidence for original antigenic sin in spontaneous thyroid autoimmunity is revealed by autoantibody interactions with immunodominant regions on thyroid autoantigens, thyroglobulin (Tg, thyroid peroxidase (TPO, and the thyrotropin receptor (TSHR A-subunit. In contrast, antibodies induced by immunization of rabbits or mice recognize diverse epitopes. Recognition of immunodominant regions persists despite fluctuations in autoantibody levels following treatment or over time. The enhancement of spontaneously arising pathogenic TSHR antibodies in transgenic human thyrotropin receptor/NOD.H2h4 mice by injecting a non-pathogenic form of TSHR A-subunit protein also provides evidence for original antigenic sin. From other studies, antigen presentation by B cells, not dendritic cells, is likely responsible for original antigenic sin. Recognition of restricted epitopes on the large glycosylated thyroid autoantigens (60-kDa A-subunit, 100-kDa TPO, and 600-kDa Tg facilitates exploring the amino acid locations in the immunodominant regions. Epitope spreading has also been revealed by autoantibodies in thyroid autoimmunity. In humans, and in mice that spontaneously develop autoimmunity to all three thyroid autoantigens, autoantibodies develop first to Tg and later to TPO and the TSHR A-subunit. The pattern of intermolecular epitope spreading is related in part to the thyroidal content of Tg, TPO and TSHR A-subunit and to the molecular sizes of these proteins. Importantly, the epitope spreading pattern provides a rationale for future antigen-specific manipulation to block the development of all thyroid autoantibodies by inducing tolerance to Tg, first in the autoantigen cascade. Because of its abundance, Tg may be the autoantigen of choice to explore antigen-specific treatment, preventing the development of pathogenic TSHR antibodies.

New insights into non-conventional epitopes as T cell targets: The missing link for breaking immune tolerance in autoimmune disease?

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Harbige, James; Eichmann, Martin; Peakman, Mark

2017-11-01

The mechanism by which immune tolerance is breached in autoimmune disease is poorly understood. One possibility is that post-translational modification of self-antigens leads to peripheral recognition of neo-epitopes against which central and peripheral tolerance is inadequate. Accumulating evidence points to multiple mechanisms through which non-germline encoded sequences can give rise to these non-conventional epitopes which in turn engage the immune system as T cell targets. In particular, where these modifications alter the rules of epitope engagement with MHC molecules, such non-conventional epitopes offer a persuasive explanation for associations between specific HLA alleles and autoimmune diseases. In this review article, we discuss current understanding of mechanisms through which non-conventional epitopes may be generated, focusing on several recently described pathways that can transpose germline-encoded sequences. We contextualise these discoveries around type 1 diabetes, the prototypic organ-specific autoimmune disease in which specific HLA-DQ molecules confer high risk. Non-conventional epitopes have the potential to act as tolerance breakers or disease drivers in type 1 diabetes, prompting a timely re-evaluation of models of a etiopathogenesis. Future studies are required to elucidate the disease-relevance of a range of potential non-germline epitopes and their relationship to the natural peptide repertoire. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structural and Functional Characterization of Anti-A33 Antibodies Reveal a Potent Cross-Species Orthopoxviruses Neutralizer.

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Michael H Matho

2015-09-01

Full Text Available Vaccinia virus A33 is an extracellular enveloped virus (EEV-specific type II membrane glycoprotein that is essential for efficient EEV formation and long-range viral spread within the host. A33 is a target for neutralizing antibody responses against EEV. In this study, we produced seven murine anti-A33 monoclonal antibodies (MAbs by immunizing mice with live VACV, followed by boosting with the soluble A33 homodimeric ectodomain. Five A33 specific MAbs were capable of neutralizing EEV in the presence of complement. All MAbs bind to conformational epitopes on A33 but not to linear peptides. To identify the epitopes, we have adetermined the crystal structures of three representative neutralizing MAbs in complex with A33. We have further determined the binding kinetics for each of the three antibodies to wild-type A33, as well as to engineered A33 that contained single alanine substitutions within the epitopes of the three crystallized antibodies. While the Fab of both MAbs A2C7 and A20G2 binds to a single A33 subunit, the Fab from MAb A27D7 binds to both A33 subunits simultaneously. A27D7 binding is resistant to single alanine substitutions within the A33 epitope. A27D7 also demonstrated high-affinity binding with recombinant A33 protein that mimics other orthopoxvirus strains in the A27D7 epitope, such as ectromelia, monkeypox, and cowpox virus, suggesting that A27D7 is a potent cross-neutralizer. Finally, we confirmed that A27D7 protects mice against a lethal challenge with ectromelia virus.

Pan-ebolavirus and Pan-filovirus Mouse Monoclonal Antibodies: Protection against Ebola and Sudan Viruses.

Science.gov (United States)

Holtsberg, Frederick W; Shulenin, Sergey; Vu, Hong; Howell, Katie A; Patel, Sonal J; Gunn, Bronwyn; Karim, Marcus; Lai, Jonathan R; Frei, Julia C; Nyakatura, Elisabeth K; Zeitlin, Larry; Douglas, Robin; Fusco, Marnie L; Froude, Jeffrey W; Saphire, Erica Ollmann; Herbert, Andrew S; Wirchnianski, Ariel S; Lear-Rooney, Calli M; Alter, Galit; Dye, John M; Glass, Pamela J; Warfield, Kelly L; Aman, M Javad

2016-01-01

The unprecedented 2014-2015 Ebola virus disease (EVD) outbreak in West Africa has highlighted the need for effective therapeutics against filoviruses. Monoclonal antibody (MAb) cocktails have shown great potential as EVD therapeutics; however, the existing protective MAbs are virus species specific. Here we report the development of pan-ebolavirus and pan-filovirus antibodies generated by repeated immunization of mice with filovirus glycoproteins engineered to drive the B cell responses toward conserved epitopes. Multiple pan-ebolavirus antibodies were identified that react to the Ebola, Sudan, Bundibugyo, and Reston viruses. A pan-filovirus antibody that was reactive to the receptor binding regions of all filovirus glycoproteins was also identified. Significant postexposure efficacy of several MAbs, including a novel antibody cocktail, was demonstrated. For the first time, we report cross-neutralization and in vivo protection against two highly divergent filovirus species, i.e., Ebola virus and Sudan virus, with a single antibody. Competition studies indicate that this antibody targets a previously unrecognized conserved neutralizing epitope that involves the glycan cap. Mechanistic studies indicated that, besides neutralization, innate immune cell effector functions may play a role in the antiviral activity of the antibodies. Our findings further suggest critical novel epitopes that can be utilized to design effective cocktails for broad protection against multiple filovirus species. Filoviruses represent a major public health threat in Africa and an emerging global concern. Largely driven by the U.S. biodefense funding programs and reinforced by the 2014 outbreaks, current immunotherapeutics are primarily focused on a single filovirus species called Ebola virus (EBOV) (formerly Zaire Ebola virus). However, other filoviruses including Sudan, Bundibugyo, and Marburg viruses have caused human outbreaks with mortality rates as high as 90%. Thus, cross

Public epitopes and the antigenic structure of the HLA molecules.

Science.gov (United States)

Rodey, G E; Fuller, T C

1987-01-01

private epitopes will be important if epitope-specific immunological probes are use to map specific regions of an MHC molecule. Many investigators are interested in the possibility that some components of HLA alloimmunization are regulated through idiotypic networks. Suciu-Foca and colleagues have provided preliminary evidence that epitope-specific HLA alloantibodies bear dominant idiotypic determinants. Antibodies to these determinants appear during pregnancy, following blood tranfusion, and following renal allograft transplantation, also, the antibodies have been correlated with renal allograft survival.(ABSTRACT TRUNCATED AT 400 WORDS)

ArrayPitope: Automated Analysis of Amino Acid Substitutions for Peptide Microarray-Based Antibody Epitope Mapping

DEFF Research Database (Denmark)

Hansen, Christian Skjødt; Østerbye, Thomas; Marcatili, Paolo

2017-01-01

-reactivity. B cell epitopes are typically classified as either linear epitopes, i.e. short consecutive segments from the protein sequence or conformational epitopes adapted through native protein folding. Recent advances in high-density peptide microarrays enable high-throughput, high-resolution identification...

Overlapping but distinct specificities of anti-liver-kidney microsome antibodies in autoimmune hepatitis type II and hepatitis C revealed by recombinant native CYP2D6 and novel peptide epitopes

Science.gov (United States)

Klein, R; Zanger, U M; Berg, T; Hopf, U; Berg, P A

1999-01-01

Anti-liver-kidney microsome antibodies (anti-LKM) occur in autoimmune hepatitis (AIH) type II and in a subset of patients with hepatitis C. Anti-LKM1 in AIH are directed against cytochrome P4502D6 (CYP2D6), but conflicting data exist concerning the specificity of anti-LKM in hepatitis C. The aim of this study was to evaluate binding specificities of anti-LKM antibodies in both diseases using novel test antigens as well as their inhibitory capacity on CYP2D6 enzyme activity. Sera from 22 patients with AIH type II and 17 patients with hepatitis C being anti-LKM-positive in the immunofluorescence test were investigated for binding to native recombinant CYP2D6 and liver microsomes by ELISA and immunoblotting, and to synthetic peptides covering the region 254–339 (254–273, 257–269, 270–294, 291–310, 307–324, 321–339, 373–389) as well as the novel peptide 196–218 by ELISA. Furthermore, all sera were tested for inhibition of CYP2D6-dependent bufuralol 1′-hydroxylase activity. Twenty of the 22 AIH type II sera (91%) and nine of the 17 hepatitis C sera (53%) were positive for CYP2D6 by ELISA and/or immunoblotting. The previously described major peptide epitope comprising CYP2D6 amino acids 257–269 was recognized by 16 of the 22 AIH sera but by only one hepatitis C serum. A further epitope, 196–218, could be defined for the first time as another immunodominant epitope for AIH because it was recognized by 15 of the 22 AIH (68%) but only three of the 17 hepatitis C sera (18%). With the exception of the peptide 254–273, the other peptides showed no significant reactivity. Analysing the inhibitory properties of anti-LKM antibodies it emerged that 95% of AIH sera and 88% of hepatitis C sera inhibited enzyme function. These data indicate that anti-LKM antibodies in AIH and hepatitis C react with CYP2D6, as shown by their inhibitory activity, and that besides the known epitope 257–269 a further immunodominant epitope exists on CYP2D6 which is recognized

Machine learning-based methods for prediction of linear B-cell epitopes.

Science.gov (United States)

Wang, Hsin-Wei; Pai, Tun-Wen

2014-01-01

B-cell epitope prediction facilitates immunologists in designing peptide-based vaccine, diagnostic test, disease prevention, treatment, and antibody production. In comparison with T-cell epitope prediction, the performance of variable length B-cell epitope prediction is still yet to be satisfied. Fortunately, due to increasingly available verified epitope databases, bioinformaticians could adopt machine learning-based algorithms on all curated data to design an improved prediction tool for biomedical researchers. Here, we have reviewed related epitope prediction papers, especially those for linear B-cell epitope prediction. It should be noticed that a combination of selected propensity scales and statistics of epitope residues with machine learning-based tools formulated a general way for constructing linear B-cell epitope prediction systems. It is also observed from most of the comparison results that the kernel method of support vector machine (SVM) classifier outperformed other machine learning-based approaches. Hence, in this chapter, except reviewing recently published papers, we have introduced the fundamentals of B-cell epitope and SVM techniques. In addition, an example of linear B-cell prediction system based on physicochemical features and amino acid combinations is illustrated in details.

Epitope mapping of the carcinoembryonic antigen by monoclonal antibodies and establishment of a new improved radioimmunoassay system

International Nuclear Information System (INIS)

Kuroki, Masahide; Arakawa, Fumiko; Matsunaga, Akira; Okamoto, Naomi; Takakura, Kyoko; Matsuoka, Yuji; Higuchi, Hiroshi.

1987-01-01

A comprehensive mapping of epitopes on the carcinoembryonic antigen (CEA) molecule has been achieved by analyses of the specificities of 146 monoclonal antibodies (MAbs) from more than 300 hybridomas established recently. The reactivities of MAbs were analyzed by radio-immunoassays (RIA) with highly purified preparations of CEA and related antigens including normal fecal antigen-1 (NFA-1), NFA-2 in normal adult feces, nonspecific cross-reacting antigen (NCA) in lung and NCA-2 in meconium. The MAbs could be divided into five groups: group I, 23 clones directed to the NCA-common part of the CEA molecule; group II, 31 clones directed to the normal fecal cross-reacting antigen (NFCA)-common part; group III, 46 clones directed to the NFA-1-common part; group IV, 33 clones reactive with the heterogeneous carbohydrate part; and group V, 13 clones directed to the CEA-distinctive part which seemed to be highly specific for CEA. Mutual inhibitions of CEA binding between MAbs of the individual groups revealed that at least 25 different subgroups can be defined i.e., 4, 7, 8, 4, and 2 subgroups in groups I to V, respectively. The epitopes recognized by the group IV MAbs were found to be sensitive to oxidation with periodate, while the epitopes defined by MAbs of the other groups were resistant to this treatment. A solid-phase sandwich-type RIA system for CEA was established by using 2 MAbs from groups II and III as the CEA catcher and an MAb of group V as the tracer. This assay was shown to exhibit improved cancer-specificity and accuracy in the estimation of serum CEA levels. (author)

IDEPI: rapid prediction of HIV-1 antibody epitopes and other phenotypic features from sequence data using a flexible machine learning platform.

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N Lance Hepler

2014-09-01

Full Text Available Since its identification in 1983, HIV-1 has been the focus of a research effort unprecedented in scope and difficulty, whose ultimate goals--a cure and a vaccine--remain elusive. One of the fundamental challenges in accomplishing these goals is the tremendous genetic variability of the virus, with some genes differing at as many as 40% of nucleotide positions among circulating strains. Because of this, the genetic bases of many viral phenotypes, most notably the susceptibility to neutralization by a particular antibody, are difficult to identify computationally. Drawing upon open-source general-purpose machine learning algorithms and libraries, we have developed a software package IDEPI (IDentify EPItopes for learning genotype-to-phenotype predictive models from sequences with known phenotypes. IDEPI can apply learned models to classify sequences of unknown phenotypes, and also identify specific sequence features which contribute to a particular phenotype. We demonstrate that IDEPI achieves performance similar to or better than that of previously published approaches on four well-studied problems: finding the epitopes of broadly neutralizing antibodies (bNab, determining coreceptor tropism of the virus, identifying compartment-specific genetic signatures of the virus, and deducing drug-resistance associated mutations. The cross-platform Python source code (released under the GPL 3.0 license, documentation, issue tracking, and a pre-configured virtual machine for IDEPI can be found at https://github.com/veg/idepi.

Epitope Identification and Application for Diagnosis of Duck Tembusu Virus Infections in Ducks

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Chenxi Li

2016-11-01

Full Text Available Duck Tembusu virus (DTMUV causes substantial egg drop disease. DTMUV was first identified in China and rapidly spread to Malaysia and Thailand. The antigenicity of the DTMUV E protein has not yet been characterized. Here, we investigated antigenic sites on the E protein using the non-neutralizing monoclonal antibodies (mAbs 1F3 and 1A5. Two minimal epitopes were mapped to 221LD/NLPW225 and 87YAEYI91 by using phage display and mutagenesis. DTMUV-positive duck sera reacted with the epitopes, thus indicating the importance of the minimal amino acids of the epitopes for antibody-epitope binding. The performance of the dot blotting assay with the corresponding positive sera indicated that YAEYI was DTMUV type-specific, whereas 221LD/NLPW225 was a cross-reactive epitope for West Nile virus (WNV, dengue virus (DENV, and Japanese encephalitis virus (JEV and corresponded to conserved and variable amino acid sequences among these strains. The structure model of the E protein revealed that YAEYI and LD/NLPW were located on domain (D II, which confirmed that DII might contain a type-specific non-neutralizing epitope. The YAEYI epitope-based antigen demonstrated its diagnostic potential by reacting with high specificity to serum samples obtained from DTMUV-infected ducks. Based on these observations, a YAEYI-based serological test could be used for DTMUV surveillance and could differentiate DTMUV infections from JEV or WNV infections. These findings provide new insights into the organization of epitopes on flavivirus E proteins that might be valuable for the development of epitope-based serological diagnostic tests for DTMUV.

Anti-NMDA-receptor encephalitis: case series and analysis of the effects of antibodies.

Science.gov (United States)

Dalmau, Josep; Gleichman, Amy J; Hughes, Ethan G; Rossi, Jeffrey E; Peng, Xiaoyu; Lai, Meizan; Dessain, Scott K; Rosenfeld, Myrna R; Balice-Gordon, Rita; Lynch, David R

2008-12-01

A severe form of encephalitis associated with antibodies against NR1-NR2 heteromers of the NMDA receptor was recently identified. We aimed to analyse the clinical and immunological features of patients with the disorder and examine the effects of antibodies against NMDA receptors in neuronal cultures. We describe the clinical characteristics of 100 patients with encephalitis and NR1-NR2 antibodies. HEK293 cells ectopically expressing single or assembled NR1-NR2 subunits were used to determine the epitope targeted by the antibodies. Antibody titres were measured with ELISA. The effect of antibodies on neuronal cultures was determined by quantitative analysis of NMDA-receptor clusters. Median age of patients was 23 years (range 5-76 years); 91 were women. All patients presented with psychiatric symptoms or memory problems; 76 had seizures, 88 unresponsiveness (decreased consciousness), 86 dyskinesias, 69 autonomic instability, and 66 hypoventilation. 58 (59%) of 98 patients for whom results of oncological assessments were available had tumours, most commonly ovarian teratoma. Patients who received early tumour treatment (usually with immunotherapy) had better outcome (p=0.004) and fewer neurological relapses (p=0.009) than the rest of the patients. 75 patients recovered or had mild deficits and 25 had severe deficits or died. Improvement was associated with a decrease of serum antibody titres. The main epitope targeted by the antibodies is in the extracellular N-terminal domain of the NR1 subunit. Patients' antibodies decreased the numbers of cell-surface NMDA receptors and NMDA-receptor clusters in postsynaptic dendrites, an effect that could be reversed by antibody removal. A well-defined set of clinical characteristics are associated with anti-NMDA-receptor encephalitis. The pathogenesis of the disorder seems to be mediated by antibodies.

Production and characterization of human anti-V3 monoclonal antibodies from the cells of HIV-1 infected Indian donors

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Andrabi Raiees

2012-09-01

Full Text Available Abstract Background Analysis of human monoclonal antibodies (mAbs developed from HIV-1 infected donors have enormously contributed to the identification of neutralization sensitive epitopes on the HIV-1 envelope glycoprotein. The third variable region (V3 is a crucial target on gp120, primarily due to its involvement in co-receptor (CXCR4 or CCR5 binding and presence of epitopes recognized by broadly neutralizing antibodies. Methods Thirty-three HIV-1 seropositive drug naive patients (18 males and 15 females within the age range of 20–57 years (median = 33 years were recruited in this study for mAb production. The mAbs were selected from EBV transformed cultures with conformationally constrained Cholera-toxin-B containing V3C (V3C-CTB fusion protein. We tested the mAbs for their binding with HIV-1 derived proteins and peptides by ELISA and for neutralization against HIV-1 viruses by TZM-bl assays. Results We isolated three anti-V3 mAbs, 277, 903 and 904 from the cells of different individuals. The ELISA binding revealed a subtype-C and subtype-A specific binding of antibody 277 and 903 while mAb 904 exhibited cross reactivity also with subtype-B V3. Epitope mapping of mAbs with overlapping V3 peptides showed exclusive binding to V3 crown. The antibodies displayed high and low neutralizing activity against 2/5 tier 1 and 1/6 tier 2 viruses respectively. Overall, we observed a resistance of the tier 2 viruses to neutralization by the anti-V3 mAbs, despite the exposure of the epitopes recognized by these antibodies on two representative native viruses (Du156.12 and JRFL, suggesting that the affinity of mAb might equally be crucial for neutralization, as the epitope recognition. Conclusions Our study suggests that the anti-V3 antibodies derived from subtype-C infected Indian patients display neutralization potential against tier 1 viruses while such activity may be limited against more resistant tier 2 viruses. Defining the fine epitope

Immune epitope database analysis resource

DEFF Research Database (Denmark)

Kim, Yohan; Ponomarenko, Julia; Zhu, Zhanyang

2012-01-01

The immune epitope database analysis resource (IEDB-AR: http://tools.iedb.org) is a collection of tools for prediction and analysis of molecular targets of T- and B-cell immune responses (i.e. epitopes). Since its last publication in the NAR webserver issue in 2008, a new generation of peptide......, and the homology mapping tool was updated to enable mapping of discontinuous epitopes onto 3D structures. Furthermore, to serve a wider range of users, the number of ways in which IEDB-AR can be accessed has been expanded. Specifically, the predictive tools can be programmatically accessed using a web interface...

Shared epitopes of glycoprotein A and protein 4.1 defined by antibody NaM10-3C10.

Science.gov (United States)

Rasamoelisolo, M; Czerwinski, M; Willem, C; Blanchard, D

1998-06-01

We have produced the murine monoclonal antibody (MAb) NaM70-3C10 (IgM) from splenocytes of mice immunized with human red blood cells (RBCs). The MAb agglutinated untreated as well as trypsin, chymotrypsin, neuraminidase, or ficin-treated RBCs from controls. In contrast, control RBCs treated with papaine or bromelaine were not agglutinated. On immunoblots, the MAb bound to glycophorin A (GPA) and to a 80 kDa protein identified as protein 4.1. Analysis by agglutination of variant RBCs carrying hybrid glycophorins made of the N-terminus (amino acids 1-58) of GPA and of the C-terminus (amino acids 27-72) of glycophorin B (GPB) and competition-inhibition test using purified GPA and a synthetic peptide corresponding to the amino acid sequence 48-58 of GPA demonstrated that the epitope is located within residues 48-58 of GPA. Epitope analysis with immobilized peptides showed that the MAb recognizes the sequence 53Pro-Pro-Glu-Glu-GIu58 of GPA. A homologous sequence is also present within amino acids 395 to 405 of protein 4.1. Finally, the MAb bound to 16 kDa chymotryptic peptide of protein 4.1, which carries the above amino acid sequence. In conclusion, it may be assumed that NaM70-3C10 specifically recognizes a common epitope on the extracellular domain of GPA and on the intracellular protein 4.1; this specificity explains the persistence of the 80 kDa band on blots when RBCs are treated with papain.

Design of a Heterotetravalent Synthetic Allergen That Reflects Epitope Heterogeneity and IgE Antibody Variability to Study Mast Cell Degranulation

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Handlogten, Michael W.; Kiziltepe, Tanyel; Bilgicer, Basar

2013-01-01

SYNOPSIS This study describes the design of a heterotetravalent allergen (HtTA) as a multi-component experimental system that enables an integrative approach to study mast cell degranulation. The HtTA design allows presentation of two distinct haptens, each with a valency of two, thereby better reflecting the complexity of natural allergens by displaying epitope heterogeneity and IgE antibody variability. Using the HtTA design, synthetic allergens HtTA-1 and HtTA-2 were synthesized to model a combination of epitope/IgE affinities. HtTA-1 presented DNP and dansyl haptens (Kd = 22 and 54 nM for IgEDNP and IgEdansyl respectively), and HtTA-2 presented dansyl and the weak affinity DNP-Pro haptens (Kd = 550 nM for IgEDNP). Both HtTAs effectively induced degranulation when mast cells were primed with both IgEDNP and IgEdansyl antibodies. Interestingly, tetravalent DNP-Pro or bivalent dansyl were insufficient in stimulating a degranulation response, illustrating the significance of valency, affinity, and synergy in allergen-IgE interactions. Importantly, maximum degranulation with both HtTA-1 and HtTA-2 was observed when only 50% of the mast cell-bound IgEs were hapten specific (25% IgEdansyl + 25% IgEDNP). Taken together, this study establishes the HtTA system as a physiologically relevant experimental model and demonstrates its utility in elucidating critical mechanisms of mast cell degranulation. PMID:23050868

Broad-spectrum inhibition of HIV-1 by a monoclonal antibody directed against a gp120-induced epitope of CD4.

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Burastero, Samuele E; Frigerio, Barbara; Lopalco, Lucia; Sironi, Francesca; Breda, Daniela; Longhi, Renato; Scarlatti, Gabriella; Canevari, Silvana; Figini, Mariangela; Lusso, Paolo

2011-01-01

To penetrate susceptible cells, HIV-1 sequentially interacts with two highly conserved cellular receptors, CD4 and a chemokine receptor like CCR5 or CXCR4. Monoclonal antibodies (MAbs) directed against such receptors are currently under clinical investigation as potential preventive or therapeutic agents. We immunized Balb/c mice with molecular complexes of the native, trimeric HIV-1 envelope (Env) bound to a soluble form of the human CD4 receptor. Sera from immunized mice were found to contain gp120-CD4 complex-enhanced antibodies and showed broad-spectrum HIV-1-inhibitory activity. A proportion of MAbs derived from these mice preferentially recognized complex-enhanced epitopes. In particular, a CD4-specific MAb designated DB81 (IgG1Κ) was found to preferentially bind to a complex-enhanced epitope on the D2 domain of human CD4. MAb DB81 also recognized chimpanzee CD4, but not baboon or macaque CD4, which exhibit sequence divergence in the D2 domain. Functionally, MAb DB81 displayed broad HIV-1-inhibitory activity, but it did not exert suppressive effects on T-cell activation in vitro. The variable regions of the heavy and light chains of MAb DB81 were sequenced. Due to its broad-spectrum anti-HIV-1 activity and lack of immunosuppressive effects, a humanized derivative of MAb DB81 could provide a useful complement to current preventive or therapeutic strategies against HIV-1.

Broad-spectrum inhibition of HIV-1 by a monoclonal antibody directed against a gp120-induced epitope of CD4.

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Samuele E Burastero

Full Text Available To penetrate susceptible cells, HIV-1 sequentially interacts with two highly conserved cellular receptors, CD4 and a chemokine receptor like CCR5 or CXCR4. Monoclonal antibodies (MAbs directed against such receptors are currently under clinical investigation as potential preventive or therapeutic agents. We immunized Balb/c mice with molecular complexes of the native, trimeric HIV-1 envelope (Env bound to a soluble form of the human CD4 receptor. Sera from immunized mice were found to contain gp120-CD4 complex-enhanced antibodies and showed broad-spectrum HIV-1-inhibitory activity. A proportion of MAbs derived from these mice preferentially recognized complex-enhanced epitopes. In particular, a CD4-specific MAb designated DB81 (IgG1Κ was found to preferentially bind to a complex-enhanced epitope on the D2 domain of human CD4. MAb DB81 also recognized chimpanzee CD4, but not baboon or macaque CD4, which exhibit sequence divergence in the D2 domain. Functionally, MAb DB81 displayed broad HIV-1-inhibitory activity, but it did not exert suppressive effects on T-cell activation in vitro. The variable regions of the heavy and light chains of MAb DB81 were sequenced. Due to its broad-spectrum anti-HIV-1 activity and lack of immunosuppressive effects, a humanized derivative of MAb DB81 could provide a useful complement to current preventive or therapeutic strategies against HIV-1.

Engineering chimeric human and mouse major histocompatibility complex (MHC) class I tetramers for the production of T-cell receptor (TCR) mimic antibodies

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Bentley, Carol; Yates, Jenna; Salimi, Maryam; Greig, Jenny; Wiblin, Sarah; Hassanali, Tasneem; Banham, Alison H.

2017-01-01

Therapeutic monoclonal antibodies targeting cell surface or secreted antigens are among the most effective classes of novel immunotherapies. However, the majority of human proteins and established cancer biomarkers are intracellular. Peptides derived from these intracellular proteins are presented on the cell surface by major histocompatibility complex class I (MHC-I) and can be targeted by a novel class of T-cell receptor mimic (TCRm) antibodies that recognise similar epitopes to T-cell receptors. Humoural immune responses to MHC-I tetramers rarely generate TCRm antibodies and many antibodies recognise the α3 domain of MHC-I and β2 microglobulin (β2m) that are not directly involved in presenting the target peptide. Here we describe the production of functional chimeric human-murine HLA-A2-H2Dd tetramers and modifications that increase their bacterial expression and refolding efficiency. These chimeric tetramers were successfully used to generate TCRm antibodies against two epitopes derived from wild type tumour suppressor p53 (RMPEAAPPV and GLAPPQHLIRV) that have been used in vaccination studies. Immunisation with chimeric tetramers yielded no antibodies recognising the human α3 domain and β2m and generated TCRm antibodies capable of specifically recognising the target peptide/MHC-I complex in fully human tetramers and on the cell surface of peptide pulsed T2 cells. Chimeric tetramers represent novel immunogens for TCRm antibody production and may also improve the yield of tetramers for groups using these reagents to monitor CD8 T-cell immune responses in HLA-A2 transgenic mouse models of immunotherapy. PMID:28448627

Molecular characterization of monoclonal antibodies that inhibit acetylcholinesterase by targeting the peripheral site and backdoor region.

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Yves Bourne

Full Text Available The inhibition properties and target sites of monoclonal antibodies (mAbs Elec403, Elec408 and Elec410, generated against Electrophorus electricus acetylcholinesterase (AChE, have been defined previously using biochemical and mutagenesis approaches. Elec403 and Elec410, which bind competitively with each other and with the peptidic toxin inhibitor fasciculin, are directed toward distinctive albeit overlapping epitopes located at the AChE peripheral anionic site, which surrounds the entrance of the active site gorge. Elec408, which is not competitive with the other two mAbs nor fasciculin, targets a second epitope located in the backdoor region, distant from the gorge entrance. To characterize the molecular determinants dictating their binding site specificity, we cloned and sequenced the mAbs; generated antigen-binding fragments (Fab retaining the parental inhibition properties; and explored their structure-function relationships using complementary x-ray crystallography, homology modeling and flexible docking approaches. Hypermutation of one Elec403 complementarity-determining region suggests occurrence of antigen-driven selection towards recognition of the AChE peripheral site. Comparative analysis of the 1.9Å-resolution structure of Fab408 and of theoretical models of its Fab403 and Fab410 congeners evidences distinctive surface topographies and anisotropic repartitions of charges, consistent with their respective target sites and inhibition properties. Finally, a validated, data-driven docking model of the Fab403-AChE complex suggests a mode of binding at the PAS that fully correlates with the functional data. This comprehensive study documents the molecular peculiarities of Fab403 and Fab410, as the largest peptidic inhibitors directed towards the peripheral site, and those of Fab408, as the first inhibitor directed toward the backdoor region of an AChE and a unique template for the design of new, specific modulators of AChE catalysis.

Immunologic properties and therapeutic efficacy of a multivalent epitope-based vaccine against four Helicobacter pylori adhesins (urease, Lpp20, HpaA, and CagL) in Mongolian gerbils.

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Guo, Le; Yin, Runting; Xu, Guangxian; Gong, Xiaojuan; Chang, Zisong; Hong, Dantong; Liu, Hongpeng; Ding, Shuqin; Han, Xuebo; Li, Yuan; Tang, Feng; Liu, Kunmei

2017-12-01

Therapeutic vaccination is a desirable alternative for controlling Helicobacter pylori (H. pylori) infection. Attachment to the gastric mucosa is the first step in establishing bacterial colonization, and adhesins, which are on the surface of H. pylori, play a pivotal role in binding to human gastric mucosa. In the present study, we constructed a multivalent epitope-based vaccine named CFAdE with seven carefully selected antigenic fragments from four H. pylori adhesins (urease, Lpp20, HpaA and CagL). The specificity, immunogenicity and ability to produce neutralizing antibodies of CFAdE were evaluated in BALB/c mice. After that, its therapeutic efficacy and protective immune mechanisms were explored in H. pylori-infected Mongolian gerbils. The results indicated that CFAdE could induce comparatively high levels of specific antibodies against urease, Lpp20, HpaA and CagL. Additionally, oral therapeutic immunization with CFAdE plus polysaccharide adjuvant (PA) significantly decreased H. pylori colonization compared with oral immunization with urease plus PA, and the protection was correlated with IgG and sIgA antibody and antigen-specific CD4 + T cells. This study indicated that the multivalent epitope-based vaccine, which targeted multiple adhesins in adherence of H. pylori to the gastric mucosa, is more effective than the univalent vaccine targeting urease only. This multivalent epitope-based vaccine may be a promising therapeutic candidate vaccine against H. pylori infection. © 2017 John Wiley & Sons Ltd.

Characterisation of a protective linear B cell epitope against feline parvoviruses

NARCIS (Netherlands)

Langeveld, J.P.; Martinez Torrecuadrada, J.; Boshuizen, R.S.; Meloen, R.H.; Ignacio Casal, J.

2001-01-01

Monoclonal antibody 3C9 was the starting material in the definition of the epitope that led to the synthesis of the first efficient peptide vaccine against a viral disease (canine parvovirus) in the natural host (dog). In this report, we have analysed the specificity of the antibody at the single

Identification of a defined linear epitope in the OspA protein of the Lyme disease spirochetes that elicits bactericidal antibody responses: Implications for vaccine development.

Science.gov (United States)

Izac, Jerilyn R; Oliver, Lee D; Earnhart, Christopher G; Marconi, Richard T

2017-05-31

The lipoprotein OspA is produced by the Lyme disease spirochetes primarily in unfed ticks. OspA production is down-regulated by the blood meal and it is not produced in mammals except for possible transient production during late stage infection in patients with Lyme arthritis. Vaccination with OspA elicits antibody (Ab) that can target spirochetes in the tick midgut during feeding and inhibit transmission to mammals. OspA was the primary component of the human LYMErix™ vaccine. LYMErix™ was available from 1998 to 2002 but then pulled from the market due to declining sales as a result of unsubstantiated concerns about vaccination induced adverse events and poor efficacy. It was postulated that a segment of OspA that shares sequence similarity with a region in human LFA-1 and may trigger putative autoimmune events. While evidence supporting such a link has not been demonstrated, most efforts to move forward with OspA as a vaccine component have sought to eliminate this region of concern. Here we identify an OspA linear epitope localized within OspA amino acid residues 221-240 (OspA 221-240 ) that lacks the OspA region suggested to elicit autoimmunity. A peptide consisting of residues 221-240 was immunogenic in mice. Ab raised against OspA 221-240 peptide surface labeled B. burgdorferi in IFAs and displayed potent Ab mediated-complement dependent bactericidal activity. BLAST analyses identified several variants of OspA 221-240 and a closely related sequence in OspB. It is our hypothesis that integration of the OspA 221-240 epitope into a multivalent-OspC based chimeric epitope based vaccine antigen (chimeritope) could result in a subunit vaccine that protects against Lyme disease through synergistic mechanisms. Copyright © 2017. Published by Elsevier Ltd.

Identification of a variant antigenic neutralizing epitope in hypervariable region 1 of avian leukosis virus subgroup J.

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Hou, Minbo; Zhou, Defang; Li, Gen; Guo, Huijun; Liu, Jianzhu; Wang, Guihua; Zheng, Qiankun; Cheng, Ziqiang

2016-03-08

Avian leukosis virus subgroup J (ALV-J) is a hypervariable oncogenic retrovirus that causes great economic loss in poultry. Antigenic variations in the variable regions make the development of an effective vaccine a challenging task. In the present study, we identified a variant antigenic neutralizing epitope using reverse vaccinology methods. First, we predicted the B-cell epitopes in gp85 gene of ALV-J strains by DNAman and bioinformatics. Fourteen candidate epitopes were selected and linked in tandem with glycines or serines as a multi-epitope gene. The expressed protein of multi-epitope gene can induce high-titer antibody that can recognize nature ALV-J and neutralize the infectivity of ALV-J strains. Next, we identified a high effective epitope using eight overlapping fragments of gp85 gene reacting with mAb 2D5 and anti-multi-epitope sera. The identified epitope contained one of the predicted epitopes and localized in hyervariable region 1 (hr1), indicating a variant epitope. To better understand if the variants of the epitope have a good antigenicity, we synthesized four variants to react with mAb 2D5 and anti-ALV-J sera. The result showed that all variants could react with the two kinds of antibodies though they showed different antigenicity, while could not react with ALV-J negative sera. Thus, the variant antigenic neutralizing epitope was determined as 137-LRDFIA/E/TKWKS/GDDL/HLIRPYVNQS-158. The result shows a potential use of this variant epitopes as a novel multi-epitope vaccine against ALV-J in poultry. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detection of Antibodies in Blood Plasma Using Bioluminescent Sensor Proteins and a Smartphone.

Science.gov (United States)

Arts, Remco; den Hartog, Ilona; Zijlema, Stefan E; Thijssen, Vito; van der Beelen, Stan H E; Merkx, Maarten

2016-04-19

Antibody detection is of fundamental importance in many diagnostic and bioanalytical assays, yet current detection techniques tend to be laborious and/or expensive. We present a new sensor platform (LUMABS) based on bioluminescence resonance energy transfer (BRET) that allows detection of antibodies directly in solution using a smartphone as the sole piece of equipment. LUMABS are single-protein sensors that consist of the blue-light emitting luciferase NanoLuc connected via a semiflexible linker to the green fluorescent acceptor protein mNeonGreen, which are kept close together using helper domains. Binding of an antibody to epitope sequences flanking the linker disrupts the interaction between the helper domains, resulting in a large decrease in BRET efficiency. The resulting change in color of the emitted light from green-blue to blue can be detected directly in blood plasma, even at picomolar concentrations of antibody. Moreover, the modular architecture of LUMABS allows changing of target specificity by simple exchange of epitope sequences, as demonstrated here for antibodies against HIV1-p17, hemagglutinin (HA), and dengue virus type I. The combination of sensitive ratiometric bioluminescent detection and the intrinsic modularity of the LUMABS design provides an attractive generic platform for point-of-care antibody detection that avoids the complex liquid handling steps associated with conventional immunoassays.

Anti-S100A4 antibody suppresses metastasis formation by blocking stroma cell invasion

DEFF Research Database (Denmark)

Klingelhöfer, Jörg; Grum-Schwensen, Birgitte; Beck, Mette K

2012-01-01

microenvironment, making it an attractive target for anti-cancer therapy. In this study, we produced a function-blocking anti-S100A4 monoclonal antibody with metastasis-suppressing activity. Antibody treatment significantly reduced metastatic burden in the lungs of experimental animals by blocking the recruitment...... of T cells to the site of the primary tumor. In vitro studies demonstrated that this antibody efficiently reduced the invasion of T cells in a fibroblast monolayer. Moreover, it was capable of suppressing the invasive growth of human and mouse fibroblasts. We presume therefore that the antibody exerts...... its activity by suppressing stroma cell recruitment to the site of the growing tumor. Our epitope mapping studies suggested that the antibody recognition site overlaps with the target binding interface of human S100A4. We conclude here that this antibody could serve as a solid basis for development...

Epitope-dependent functional effects of celiac disease autoantibodies on transglutaminase 2

DEFF Research Database (Denmark)

Hnida, Kathrin; Stamnaes, Jorunn; du Pré, M Fleur

2016-01-01

Transglutaminase 2 (TG2) is a Ca(2+)-dependent cross-linking enzyme involved in the pathogenesis of CD. We have previously characterized a panel of anti-TG2 mAbs generated from gut plasma cells of celiac patients and identified four epitopes (epitopes 1-4) located in the N-terminal part of TG2...... of epitope 1-targeting B cells to keep TG2 active and protected from oxidation might explain why generation of epitope 1-targeting plasma cells seems to be favored in celiac patients....

A "Trojan horse" bispecific-antibody strategy for broad protection against ebolaviruses.

Science.gov (United States)

Wec, Anna Z; Nyakatura, Elisabeth K; Herbert, Andrew S; Howell, Katie A; Holtsberg, Frederick W; Bakken, Russell R; Mittler, Eva; Christin, John R; Shulenin, Sergey; Jangra, Rohit K; Bharrhan, Sushma; Kuehne, Ana I; Bornholdt, Zachary A; Flyak, Andrew I; Saphire, Erica Ollmann; Crowe, James E; Aman, M Javad; Dye, John M; Lai, Jonathan R; Chandran, Kartik

2016-10-21

There is an urgent need for monoclonal antibody (mAb) therapies that broadly protect against Ebola virus and other filoviruses. The conserved, essential interaction between the filovirus glycoprotein, GP, and its entry receptor Niemann-Pick C1 (NPC1) provides an attractive target for such mAbs but is shielded by multiple mechanisms, including physical sequestration in late endosomes. Here, we describe a bispecific-antibody strategy to target this interaction, in which mAbs specific for NPC1 or the GP receptor-binding site are coupled to a mAb against a conserved, surface-exposed GP epitope. Bispecific antibodies, but not parent mAbs, neutralized all known ebolaviruses by coopting viral particles themselves for endosomal delivery and conferred postexposure protection against multiple ebolaviruses in mice. Such "Trojan horse" bispecific antibodies have potential as broad antifilovirus immunotherapeutics. Copyright © 2016, American Association for the Advancement of Science.

New Strategies Using Antibody Combinations to Increase Cancer Treatment Effectiveness

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Isabel Corraliza-Gorjón

2017-12-01

Full Text Available Antibodies have proven their high value in antitumor therapy over the last two decades. They are currently being used as the first-choice to treat some of the most frequent metastatic cancers, like HER2+ breast cancers or colorectal cancers, currently treated with trastuzumab (Herceptin and bevacizumab (Avastin, respectively. The impressive therapeutic success of antibodies inhibiting immune checkpoints has extended the use of therapeutic antibodies to previously unanticipated tumor types. These anti-immune checkpoint antibodies allowed the cure of patients devoid of other therapeutic options, through the recovery of the patient’s own immune response against the tumor. In this review, we describe how the antibody-based therapies will evolve, including the use of antibodies in combinations, their main characteristics, advantages, and how they could contribute to significantly increase the chances of success in cancer therapy. Indeed, novel combinations will consist of mixtures of antibodies against either different epitopes of the same molecule or different targets on the same tumor cell; bispecific or multispecific antibodies able of simultaneously binding tumor cells, immune cells or extracellular molecules; immunomodulatory antibodies; antibody-based molecules, including fusion proteins between a ligand or a receptor domain and the IgG Fab or Fc fragments; autologous or heterologous cells; and different formats of vaccines. Through complementary mechanisms of action, these combinations could contribute to elude the current limitations of a single antibody which recognizes only one particular epitope. These combinations may allow the simultaneous attack of the cancer cells by using the help of the own immune cells and exerting wider therapeutic effects, based on a more specific, fast, and robust response, trying to mimic the action of the immune system.

Selection of phage-displayed accessible recombinant targeted antibodies (SPARTA): methodology and applications.

Science.gov (United States)

D'Angelo, Sara; Staquicini, Fernanda I; Ferrara, Fortunato; Staquicini, Daniela I; Sharma, Geetanjali; Tarleton, Christy A; Nguyen, Huynh; Naranjo, Leslie A; Sidman, Richard L; Arap, Wadih; Bradbury, Andrew Rm; Pasqualini, Renata

2018-05-03

We developed a potentially novel and robust antibody discovery methodology, termed selection of phage-displayed accessible recombinant targeted antibodies (SPARTA). This combines an in vitro screening step of a naive human antibody library against known tumor targets, with in vivo selections based on tumor-homing capabilities of a preenriched antibody pool. This unique approach overcomes several rate-limiting challenges to generate human antibodies amenable to rapid translation into medical applications. As a proof of concept, we evaluated SPARTA on 2 well-established tumor cell surface targets, EphA5 and GRP78. We evaluated antibodies that showed tumor-targeting selectivity as a representative panel of antibody-drug conjugates (ADCs) and were highly efficacious. Our results validate a discovery platform to identify and validate monoclonal antibodies with favorable tumor-targeting attributes. This approach may also extend to other diseases with known cell surface targets and affected tissues easily isolated for in vivo selection.

Human vaccination against RH5 induces neutralizing antimalarial antibodies that inhibit RH5 invasion complex interactions

DEFF Research Database (Denmark)

Payne, Ruth O; Silk, Sarah E; Elias, Sean C

2017-01-01

serum antibodies exhibited cross-strain functional growth inhibition activity (GIA) in vitro, targeted linear and conformational epitopes within RH5, and inhibited key interactions within the RH5 invasion complex. This is the first time to our knowledge that substantial RH5-specific responses have been...

Characterization of a Large Panel of Rabbit Monoclonal Antibodies against HIV-1 gp120 and Isolation of Novel Neutralizing Antibodies against the V3 Loop.

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Yali Qin

Full Text Available We recently reported the induction of potent, cross-clade neutralizing antibodies (nAbs against Human Immunodeficiency Virus type-1 (HIV-1 in rabbits using gp120 based on an M-group consensus sequence. To better characterize these antibodies, 93 hybridomas were generated, which represent the largest panel of monoclonal antibodies (mAbs ever generated from a vaccinated rabbit. The single most frequently recognized epitope of the isolated mAbs was at the very C-terminal end of the protein (APTKAKRRVVEREKR, followed by the V3 loop. A total of seven anti-V3 loop mAbs were isolated, two of which (10A3 and 10A37 exhibited neutralizing activity. In contrast to 10A3 and most other anti-V3 loop nAbs, 10A37 was atypical with its epitope positioned more towards the C-terminal half of the loop. To our knowledge, 10A37 is the most potent and broadly neutralizing anti-V3 loop mAb induced by vaccination. Interestingly, all seven anti-V3 loop mAbs competed with PGT121, suggesting a possibility that early induction of potent anti-V3 loop antibodies could prevent induction of more broadly neutralizing PGT121-like antibodies that target the conserved base of the V3 loop stem.

Broadly neutralizing antibodies for treatment and prevention of HIV-1 infection.

Science.gov (United States)

Cohen, Yehuda Z; Caskey, Marina

2018-04-24

Several anti-HIV-1 broadly neutralizing antibodies (bNAbs) with exceptional breadth and potency that target different HIV-1 envelope epitopes have been identified. bNAbs are an attractive new strategy for HIV-1 prevention and therapy, and potentially, for long-term remission or cure. Here, we discuss findings from early clinical studies that have evaluated these novel bNAbs. Phase 1 studies of bNAbs targeting two distinct HIV-1 envelope epitopes have demonstrated their favorable safety and pharmacokinetic profile. Single bNAb infusions led to significant, but transient, decline in viremia with selection of escape variants. A single bNAb also delayed viral rebound in ART-treated participants who discontinued ART. Importantly, in-vivo efficacy was related to antibody potency and to the level of preexisting resistance. Studies in animal models showed that bNAbs can clear HIV-infected cells and modulate host immune responses. These findings suggest that bNAbs may target the latent HIV reservoir in humans and could contribute to long-term remission of HIV-1 infection. bNAbs may offer advantages over traditional ART for both the prevention and treatment of HIV-1 infection. In addition, bNAbs may target the latent viral reservoir. bNAb combinations and bNAbs engineered for prolonged half-life and increased potency are currently undergoing clinical evaluation.

Identification of a conserved B-cell epitope on the GapC protein of Streptococcus dysgalactiae.

Science.gov (United States)

Zhang, Limeng; Zhou, Xue; Fan, Ziyao; Tang, Wei; Chen, Liang; Dai, Jian; Wei, Yuhua; Zhang, Jianxin; Yang, Xuan; Yang, Xijing; Liu, Daolong; Yu, Liquan; Zhang, Hua; Wu, Zhijun; Yu, Yongzhong; Sun, Hunan; Cui, Yudong

2015-01-01

Streptococcus dysgalactiae (S. dysgalactia) GapC is a highly conserved surface dehydrogenase among the streptococcus spp., which is responsible for inducing protective antibody immune responses in animals. However, the B-cell epitope of S. dysgalactia GapC have not been well characterized. In this study, a monoclonal antibody 1F2 (mAb1F2) against S. dysgalactiae GapC was generated by the hybridoma technique and used to screen a phage-displayed 12-mer random peptide library (Ph.D.-12) for mapping the linear B-cell epitope. The mAb1F2 recognized phages displaying peptides with the consensus motif TRINDLT. Amino acid sequence of the motif exactly matched (30)TRINDLT(36) of the S. dysgalactia GapC. Subsequently, site-directed mutagenic analysis further demonstrated that residues R31, I32, N33, D34 and L35 formed the core of (30)TRINDLT(36), and this core motif was the minimal determinant of the B-cell epitope recognized by the mAb1F2. The epitope (30)TRINDLT(36) showed high homology among different streptococcus species. Overall, our findings characterized a conserved B-cell epitope, which will be useful for the further study of epitope-based vaccines. Copyright © 2015 Elsevier Ltd. All rights reserved.

Exploration of novel strategies to enhance monoclonal antibodies targeting

International Nuclear Information System (INIS)

Khawli, L.A.; Epstein, A.L.

1997-01-01

This paper highlights the major obstacles and prospects of antibody targeting for the radio imaging and therapy of human malignant lymphomas and more challenging solid tumors. To improve the therapeutic potential of monoclonal antibodies, the authors have focused their attention on the development of new and successful methods to augment antibody uptake in the tumor. These approaches include the use of radiolabeled streptavidin to target biotinylated monoclonal antibodies already bound to tumor, pretreatment with vasoactive immunoconjugates, and the use of chemically modified antibodies. Because of the promising preclinical data obtained with these three newer approaches, plans are underway to test them in the clinic. More generally, these approaches are applicable to the use of other monoclonal antibody/tumor systems for the diagnosis and therapy of human cancers and related diseases

Direct binding to antigen-coated beads refines the specificity and cross-reactivity of four monoclonal antibodies that recognize polymorphic epitopes of HLA class I molecules.

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Hilton, H G; Parham, P

2013-04-01

Monoclonal antibodies with specificity for human leukocyte antigen (HLA) class I determinants of HLA were originally characterized using serological assays in which the targets were cells expressing three to six HLA class I variants. Because of this complexity, the specificities of the antibodies were defined indirectly by correlation. Here we use a direct binding assay, in which the targets are synthetic beads coated with 1 of 111 HLA class I variants, representing the full range of HLA-A, -B and -C variation. We studied one monoclonal antibody with monomorphic specificity (W6/32) and four with polymorphic specificity (MA2.1, PA2.1, BB7.2 and BB7.1) and compared the results with those obtained previously. W6/32 reacted with all HLA class I variants. MA2.1 not only exhibits high specificity for HLA-A*02, -B*57 and -B*58, but also exhibited cross-reactivity with HLA-A*11 and -B*15:16. At low concentration (1 µg/ml), PA2.1 and BB7.2 were both specific for HLA-A*02 and -A*69, and at high concentration (50 µg/ml) exhibited significant cross-reactions with HLA-A*68, -A*23 and -A*24. BB7.1 exhibits specificity for HLA-B*07 and -B*42, as previously described, but reacts equally well with HLA-B*81, a rare allotype defined some 16 years after the description of BB7.1. The results obtained with cell-based and bead-based assays are consistent and, in combination with amino acid sequence comparison, increase understanding of the polymorphic epitopes recognized by the MA2.1, PA2.1, BB7.2 and BB7.1 antibodies. Comparison of two overlapping but distinctive bead sets from two sources gave similar results, but the overall levels of binding were significantly different. Several weaker reactions were observed with only one of the bead sets. © 2013 John Wiley & Sons A/S.

Identification of an immunodominant epitope in glycoproteins B and G of herpes simplex viruses (HSVs) using synthetic peptides as antigens in assay of antibodies to HSV in herpes simplex encephalitis patients.

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Bhullar, S S; Chandak, N H; Baheti, N N; Purohit, H J; Taori, G M; Daginawala, H F; Kashyap, R S

2014-01-01

Herpes simplex encephalitis (HSE) is a severe viral infection of the central nervous system (CNS). Assay of antibody response is widely used in diagnostics of HSE. The aim of this study was to identify an immunodominant epitope determining the antibody response to herpes simplex viruses (HSVs) in cerebrospinal fluid (CSF) of HSE patients. The synthetic peptides that resembled type-common as well as type-specific domains of glycoproteins B (gB) and G (gG) of these viruses were evaluated for binding with IgM and IgG antibodies in CSF samples from HSE and non-HSE patients in ELISA. The QLHDLRF peptide, derived from gB of HSV was found to be an immunodominant epitope in the IgM and IgG antibody response. The patients with confirmed and suspected HSE showed in ELISA against this peptide 26% and 23% positivities for IgM, 43% and 37% positivities for IgG and 17% and 15% for both IgM and IgG antibodies, respectively. The total positivities of 86% and 75% for both IgM and IgG antibodies were obtained in the patients with confirmed and suspected HSE, respectively. These results demonstrate that a synthetic peptide-based diagnostics of HSE can be an efficient and easily accessible alternative. This is the first report describing the use of synthetic peptides derived from HSVs in diagnostics of HSE using patientsʹ CSF samples.

A novel merozoite surface antigen of Plasmodium falciparum (MSP-3 identified by cellular-antibody cooperative mechanism antigenicity and biological activity of antibodies

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Claude Oeuvray

1994-01-01

Full Text Available We report the identification of a 48kDa antigen targeted by antibodies which inhibit Plasmodium falciparum in vitro growth by cooperation with blood monocytes in an ADCI assay correlated to the naturally acquired protection. This protein is located on the surface of the merozoite stage of P. falciparum, and is detectable in all isolates tested. Epidemiological studies demonstrated that peptides derived from the amino acid sequence of MSP-3 contain potent B and T-cell epitopes recognized by a majority of individuals living in endemic areas. Moreover human antibodies either purified on the recombinant protein, or on the synthetic peptide MSP-3b, as well as antibodies raised in mice, were all found to promote parasite killing mediated by monocytes.

Use of monoclonal antibodies against Hendra and Nipah viruses in an antigen capture ELISA

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Spiropoulou Christina F

2010-06-01

Full Text Available Abstract Background Outbreaks of Hendra (HeV and Nipah (NiV viruses have been reported starting in 1994 and 1998, respectively. Both viruses are capable of causing fatal disease in humans and effecting great economical loss in the livestock industry. Results Through screening of hybridomas derived from mice immunized with γ-irradiated Nipah virus, we identified two secreted antibodies; one reactive with the nucleocapsid (N protein and the other, the phosphoprotein (P of henipaviruses. Epitope mapping and protein sequence alignments between NiV and HeV suggest the last 14 amino acids of the carboxyl terminus of the N protein is the target of the anti-N antibody. The anti-P antibody recognizes an epitope in the amino-terminal half of P protein. These monoclonal antibodies were used to develop two antigen capture ELISAs, one for virus detection and the other for differentiation between NiV and HeV. The lower limit of detection of the capture assay with both monoclonal antibodies was 400 pfu. The anti-N antibody was used to successfully detect NiV in a lung tissue suspension from an infected pig. Conclusion The antigen capture ELISA developed is potentially affordable tool to provide rapid detection and differentiation between the henipaviruses.

Positive-unlabeled learning for the prediction of conformational B-cell epitopes

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2015-01-01

Background The incomplete ground truth of training data of B-cell epitopes is a demanding issue in computational epitope prediction. The challenge is that only a small fraction of the surface residues of an antigen are confirmed as antigenic residues (positive training data); the remaining residues are unlabeled. As some of these uncertain residues can possibly be grouped to form novel but currently unknown epitopes, it is misguided to unanimously classify all the unlabeled residues as negative training data following the traditional supervised learning scheme. Results We propose a positive-unlabeled learning algorithm to address this problem. The key idea is to distinguish between epitope-likely residues and reliable negative residues in unlabeled data. The method has two steps: (1) identify reliable negative residues using a weighted SVM with a high recall; and (2) construct a classification model on the positive residues and the reliable negative residues. Complex-based 10-fold cross-validation was conducted to show that this method outperforms those commonly used predictors DiscoTope 2.0, ElliPro and SEPPA 2.0 in every aspect. We conducted four case studies, in which the approach was tested on antigens of West Nile virus, dihydrofolate reductase, beta-lactamase, and two Ebola antigens whose epitopes are currently unknown. All the results were assessed on a newly-established data set of antigen structures not bound by antibodies, instead of on antibody-bound antigen structures. These bound structures may contain unfair binding information such as bound-state B-factors and protrusion index which could exaggerate the epitope prediction performance. Source codes are available on request. PMID:26681157

Dual antibody therapy to harness the innate anti-tumor immune response to enhance antibody targeting of tumors.

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Chester, Cariad; Marabelle, Aurelien; Houot, Roch; Kohrt, Holbrook E

2015-04-01

Cancer immunotherapy is a rapidly evolving field that offers a novel paradigm for cancer treatment: therapies focus on enhancing the immune system's innate and adaptive anti-tumor response. Early immunotherapeutics have achieved impressive clinical outcomes and monoclonal antibodies are now integral to therapeutic strategies in a variety of cancers. However, only recently have antibodies targeting innate immune cells entered clinical development. Innate immune effector cells play important roles in generating and maintaining antitumor immunity. Antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) are important innate immune mechanisms for tumor eradication. These cytolytic processes are initiated by the detection of a tumor-targeting antibody and can be augmented by activating co-stimulatory pathways or blocking inhibitory signals on innate immune cells. The combination of FDA-approved monoclonal antibodies with innate effector-targeting antibodies has demonstrated potent preclinical therapeutic synergy and early-phase combinatorial clinical trials are ongoing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Epitope diversification driven by non-tumor epitope-specific Th1 and Th17 mediates potent antitumor reactivity.

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Ichikawa, Kosuke; Kagamu, Hiroshi; Koyama, Kenichi; Miyabayashi, Takao; Koshio, Jun; Miura, Satoru; Watanabe, Satoshi; Yoshizawa, Hirohisa; Narita, Ichiei

2012-09-21

MHC class I-restricted peptide-based vaccination therapies have been conducted to treat cancer patients, because CD8⁺ CTL can efficiently induce apoptosis of tumor cells in an MHC class I-restricted epitope-specific manner. Interestingly, clinical responders are known to demonstrate reactivity to epitopes other than those used for vaccination; however, the mechanism underlying how antitumor T cells with diverse specificity are induced is unclear. In this study, we demonstrated that dendritic cells (DCs) that engulfed apoptotic tumor cells in the presence of non-tumor MHC class II-restricted epitope peptides, OVA(323-339), efficiently presented tumor-associated antigens upon effector-dominant CD4⁺ T cell balance against regulatory T cells (Treg) for the OVA(323-339) epitope. Th1 and Th17 induced tumor-associated antigens presentation of DC, while Th2 ameliorated tumor-antigen presentation for CD8⁺ T cells. Blocking experiments with anti-IL-23p19 antibody and anti-IL-23 receptor indicated that an autocrine mechanism of IL-23 likely mediated the diverted tumor-associated antigens presentation of DC. Tumor-associated antigens presentation of DC induced by OVA(323-339) epitope-specific CD4⁺ T cells resulted in facilitated antitumor immunity in both priming and effector phase in vivo. Notably, this immunotherapy did not require pretreatment to reduce Treg induced by tumor. This strategy may have clinical implications for designing effective antitumor immunotherapies. Copyright © 2012 Elsevier Ltd. All rights reserved.

FluKB: A Knowledge-Based System for Influenza Vaccine Target Discovery and Analysis of the Immunological Properties of Influenza Viruses

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Simon, Christian; Kudahl, Ulrich Johan; Sun, Jing

2015-01-01

FluKB is a knowledge-based system focusing on data and analytical tools for influenza vaccine discovery. The main goal of FluKB is to provide access to curated influenza sequence and epitope data and enhance the analysis of influenza sequence diversity and the analysis of targets of immune...... responses. FluKB consists of more than 400,000 influenza protein sequences, known epitope data (357 verified T-cell epitopes, 685 HLA binders, and 16 naturally processed MHC ligands), and a collection of 28 influenza antibodies and their structurally defined B-cell epitopes. FluKB was built using amodular...

Methods to uncover an antibody epitope in the KPI domain of Alzheimer's amyloid precursor protein for immunohistochemistry in human brain.

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Campbell, E; Pearson, R C; Parkinson, D

1999-11-15

A novel polyclonal antibody (Ab993), specific for a KPI domain epitope of APP, was characterised for use in immunoprecipitation, Western blotting and immunohistochemistry. Conditioned medium from NTera2/D1 cells was used for immunoprecipitation and Western blots. Paraffin-embedded human brain sections were used for immunohistochemistry. The antibody recognised KPI-containing APP on Western blots after standard solubilisation but immunoprecipitation of soluble APP required reduction with 2-mercaptoethanol followed by alkylation of reduced sulphydryl bonds with sodium iodoacetate. Immunohistochemical staining of human brain sections was significantly enhanced by this pre-treatment. Microwaving of sections also increased immunolabelling, by a mechanism that was additive to reduction and alkylation. Incubation in 80% formic acid did not confer any enhancement of immunoreactivity. Ab993, applied with the methods reported here, is expected to be valuable in investigations of the pathogenesis of Alzheimer's disease to determine the source of the beta-amyloid peptide.

Discovery of functional monoclonal antibodies targeting G-protein-coupled receptors and ion channels.

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Wilkinson, Trevor C I

2016-06-15

The development of recombinant antibody therapeutics is a significant area of growth in the pharmaceutical industry with almost 50 approved monoclonal antibodies on the market in the US and Europe. Despite this growth, however, certain classes of important molecular targets have remained intractable to therapeutic antibodies due to complexity of the target molecules. These complex target molecules include G-protein-coupled receptors and ion channels which represent a large potential target class for therapeutic intervention with monoclonal antibodies. Although these targets have typically been addressed by small molecule approaches, the exquisite specificity of antibodies provides a significant opportunity to provide selective modulation of these target proteins. Given this opportunity, substantial effort has been applied to address the technical challenges of targeting these complex membrane proteins with monoclonal antibodies. In this review recent progress made in the strategies for discovery of functional monoclonal antibodies for these challenging membrane protein targets is addressed. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

A novel method for measuring cellular antibody uptake using imaging flow cytometry reveals distinct uptake rates for two different monoclonal antibodies targeting L1.

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Hazin, John; Moldenhauer, Gerhard; Altevogt, Peter; Brady, Nathan R

2015-08-01

Monoclonal antibodies (mAbs) have emerged as a promising tool for cancer therapy. Differing approaches utilize mAbs to either deliver a drug to the tumor cells or to modulate the host's immune system to mediate tumor kill. The rate by which a therapeutic antibody is being internalized by tumor cells is a decisive feature for choosing the appropriate treatment strategy. We herein present a novel method to effectively quantitate antibody uptake of tumor cells by using image-based flow cytometry, which combines image analysis with high throughput of sample numbers and sample size. The use of this method is established by determining uptake rate of an anti-EpCAM antibody (HEA125), from single cell measurements of plasma membrane versus internalized antibody, in conjunction with inhibitors of endocytosis. The method is then applied to two mAbs (L1-9.3, L1-OV52.24) targeting the neural cell adhesion molecule L1 (L1CAM) at two different epitopes. Based on median cell population responses, we find that mAb L1-OV52.24 is rapidly internalized by the ovarian carcinoma cell line SKOV3ip while L1 mAb 9.3 is mainly retained at the cell surface. These findings suggest the L1 mAb OV52.24 as a candidate to be further developed for drug-delivery to cancer cells, while L1-9.3 may be optimized to tag the tumor cells and stimulate immunogenic cancer cell killing. Furthermore, when analyzing cell-to-cell variability, we observed L1 mAb OV52.24 rapidly transition into a subpopulation with high-internalization capacity. In summary, this novel high-content method for measuring antibody internalization rate provides a high level of accuracy and sensitivity for cell population measurements and reveals further biologically relevant information when taking into account cellular heterogeneity. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of a linear epitope on Chlamydia trachomatis serovar L2 DnaK-like protein

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Ozkokmen, D; Birkelund, Svend; Christiansen, Gunna

1994-01-01

A cytoplasmic 75-kDa immunogen from Chlamydia trachomatis serovar L2 has previously been characterized as being similar to the Escherichia coli heat shock protein DnaK. We have localized a linear epitope for one monoclonal antibody specific for C. trachomatis DnaK. By use of a recombinant DNA...... technique, the epitope was limited to 14 amino acids. With synthetic peptides, the epitope was further limited to eight amino acids. Six of these amino acids are conserved in bovine HSP70, which has a known three-dimensional structure. The amino acid sequence homologous to the epitope is located in a linear...

Recombinant immunotoxin for cancer treatment with low immunogenicity by identification and silencing of human T-cell epitopes

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Mazor, Ronit; Eberle, Jaime A.; Hu, Xiaobo; Vassall, Aaron N.; Onda, Masanori; Beers, Richard; Lee, Elizabeth C.; Kreitman, Robert J.; Lee, Byungkook; Baker, David; King, Chris; Hassan, Raffit; Benhar, Itai; Pastan, Ira

2014-01-01

Nonhuman proteins have valuable therapeutic properties, but their efficacy is limited by neutralizing antibodies. Recombinant immunotoxins (RITs) are potent anticancer agents that have produced many complete remissions in leukemia, but immunogenicity limits the number of doses that can be given to patients with normal immune systems. Using human cells, we identified eight helper T-cell epitopes in PE38, a portion of the bacterial protein Pseudomonas exotoxin A which consists of the toxin moiety of the RIT, and used this information to make LMB-T18 in which three epitopes were deleted and five others diminished by point mutations in key residues. LMB-T18 has high cytotoxic and antitumor activity and is very resistant to thermal denaturation. The new immunotoxin has a 93% decrease in T-cell epitopes and should have improved efficacy in patients because more treatment cycles can be given. Furthermore, the deimmunized toxin can be used to make RITs targeting other antigens, and the approach we describe can be used to deimmunize other therapeutically useful nonhuman proteins. PMID:24799704

Analysis of Conformational B-Cell Epitopes in the Antibody-Antigen Complex Using the Depth Function and the Convex Hull.

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Wei Zheng

Full Text Available The prediction of conformational b-cell epitopes plays an important role in immunoinformatics. Several computational methods are proposed on the basis of discrimination determined by the solvent-accessible surface between epitopes and non-epitopes, but the performance of existing methods is far from satisfying. In this paper, depth functions and the k-th surface convex hull are used to analyze epitopes and exposed non-epitopes. On each layer of the protein, we compute relative solvent accessibility and four different types of depth functions, i.e., Chakravarty depth, DPX, half-sphere exposure and half space depth, to analyze the location of epitopes on different layers of the proteins. We found that conformational b-cell epitopes are rich in charged residues Asp, Glu, Lys, Arg, His; aliphatic residues Gly, Pro; non-charged residues Asn, Gln; and aromatic residue Tyr. Conformational b-cell epitopes are rich in coils. Conservation of epitopes is not significantly lower than that of exposed non-epitopes. The average depths (obtained by four methods for epitopes are significantly lower than that of non-epitopes on the surface using the Wilcoxon rank sum test. Epitopes are more likely to be located in the outer layer of the convex hull of a protein. On the benchmark dataset, the cumulate 10th convex hull covers 84.6% of exposed residues on the protein surface area, and nearly 95% of epitope sites. These findings may be helpful in building a predictor for epitopes.

Antibody-mediated immunotherapy against chronic hepatitis B virus infection.

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Gao, Ying; Zhang, Tian-Ying; Yuan, Quan; Xia, Ning-Shao

2017-08-03

The currently available drugs to treat hepatitis B virus (HBV) infection include interferons and nucleos(t)ide analogs, which can only induce disease remission and are inefficient for the functional cure of patients with chronic HBV infection (CHB). Since high titers of circulating hepatitis B surface antigen (HBsAg) may be essential to exhaust the host anti-HBV immune response and they cannot be significantly reduced by current drugs, new antiviral strategies aiming to suppress serum hepatitis B surface antigen (HBsAg) could help restore virus-specific immune responses and promote the eradication of the virus. As an alternative strategy, immunotherapy with HBsAg-specific antibodies has shown some direct HBsAg suppression effects in several preclinical and clinical trial studies. However, most described previously HBsAg-specific antibodies only had very short-term HBsAg suppression effects in CHB patients and animal models mimicking persistent HBV infection. More-potent antibodies with long-lasting HBsAg clearance effects are required for the development of the clinical application of antibody-mediated immunotherapy for CHB treatment. Our recent study described a novel mAb E6F6 that targets a unique epitope on HBsAg. It could durably suppress the levels of HBsAg and HBV DNA via Fcγ receptor-dependent phagocytosis in vivo. In this commentary, we summarize the current research progress, including the therapeutic roles and mechanisms of antibody-mediated HBV clearance as well as the epitope-determined therapeutic potency of the antibody. These insights may provide some clues and guidance to facilitate the development of therapeutic antibodies against persistent viral infection.

A Recombinant Secondary Antibody Mimic as a Target-specific Signal Amplifier and an Antibody Immobilizer in Immunoassays.

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Min, Junseon; Song, Eun Kyung; Kim, Hansol; Kim, Kyoung Taek; Park, Tae Joo; Kang, Sebyung

2016-04-11

We construct a novel recombinant secondary antibody mimic, GST-ABD, which can bind to the Fc regions of target-bound primary antibodies and acquire multiple HRPs simultaneously. We produce it in tenth of mg quantities with a bacterial overexpression system and simple purification procedures, significantly reducing the manufacturing cost and time without the use of animals. GST-ABD is effectively conjugated with 3 HRPs per molecule on an average and selectively bind to the Fc region of primary antibodies derived from three different species (mouse, rabbit, and rat). HRP-conjugated GST-ABD (HRP-GST-ABD) is successfully used as an alternative to secondary antibodies to amplify target-specific signals in both ELISA and immunohistochemistry regardless of the target molecules and origin of primary antibodies used. GST-ABD also successfully serves as an anchoring adaptor on the surface of GSH-coated plates for immobilizing antigen-capturing antibodies in an orientation-controlled manner for sandwich-type indirect ELISA through simple molecular recognition without any complicated chemical modification.

Antibodies to actin in autoimmune haemolytic anaemia

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Ritzmann Mathias

2010-03-01

Full Text Available Abstract Background In autoimmune haemolytic anaemia (AIHA, autoreactive antibodies directed against red blood cells are up-regulated, leading to erythrocyte death. Mycoplasma suis infections in pigs induce AIHA of both the warm and cold types. The aim of this study was to identify the target autoantigens of warm autoreactive IgG antibodies. Sera from experimentally M. suis-infected pigs were screened for autoreactivity. Results Actin-reactive antibodies were found in the sera of 95% of all animals tested. The reactivity was species-specific, i.e. reactivity with porcine actin was significantly higher than with rabbit actin. Sera of animals previously immunised with the M. suis adhesion protein MSG1 showed reactivity with actin prior to infection with M. suis indicating that molecular mimicry is involved in the specific autoreactive mechanism. A potentially cross-reactive epitope was detected. Conclusions This is the first report of autoreactive anti-actin antibodies involved in the pathogenesis of autoimmune haemolytic anaemia.

Induction of neutralizing antibodies by a tobacco chloroplast-derived vaccine based on a B cell epitope from canine parvovirus.

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Molina, Andrea; Veramendi, Jon; Hervás-Stubbs, Sandra

2005-11-25

The 2L21 epitope of the VP2 protein from the canine parvovirus (CPV), fused to the cholera toxin B subunit (CTB-2L21), was expressed in transgenic tobacco chloroplasts. Mice and rabbits that received protein-enriched leaf extracts by parenteral route produced high titers of anti-2L21 antibodies able to recognize the VP2 protein. Rabbit sera were able to neutralize CPV in an in vitro infection assay with an efficacy similar to the anti-2L21 neutralizing monoclonal antibody 3C9. Anti-2L21 IgG and seric IgA antibodies were elicited when mice were gavaged with a suspension of pulverized tissues from CTB-2L21 transformed plants. Combined immunization (a single parenteral injection followed by oral boosters) shows that oral boosters help to maintain the anti-2L21 IgG response induced after a single injection, whereas parenteral administration of the antigen primes the subsequent oral boosters by promoting the induction of anti-2L21 seric IgA antibodies. Despite the induced humoral response, antibodies elicited by oral delivery did not show neutralizing capacity in the in vitro assay. The high yield of the fusion protein permits the preparation of a high number of vaccine doses from a single plant and makes feasible the oral vaccination using a small amount of crude plant material. However, a big effort has still to be done to enhance the protective efficacy of subunit vaccines by the oral route.

Induction of neutralizing antibodies by a tobacco chloroplast-derived vaccine based on a B cell epitope from canine parvovirus

International Nuclear Information System (INIS)

Molina, Andrea; Veramendi, Jon; Hervas-Stubbs, Sandra

2005-01-01

The 2L21 epitope of the VP2 protein from the canine parvovirus (CPV), fused to the cholera toxin B subunit (CTB-2L21), was expressed in transgenic tobacco chloroplasts. Mice and rabbits that received protein-enriched leaf extracts by parenteral route produced high titers of anti-2L21 antibodies able to recognize the VP2 protein. Rabbit sera were able to neutralize CPV in an in vitro infection assay with an efficacy similar to the anti-2L21 neutralizing monoclonal antibody 3C9. Anti-2L21 IgG and seric IgA antibodies were elicited when mice were gavaged with a suspension of pulverized tissues from CTB-2L21 transformed plants. Combined immunization (a single parenteral injection followed by oral boosters) shows that oral boosters help to maintain the anti-2L21 IgG response induced after a single injection, whereas parenteral administration of the antigen primes the subsequent oral boosters by promoting the induction of anti-2L21 seric IgA antibodies. Despite the induced humoral response, antibodies elicited by oral delivery did not show neutralizing capacity in the in vitro assay. The high yield of the fusion protein permits the preparation of a high number of vaccine doses from a single plant and makes feasible the oral vaccination using a small amount of crude plant material. However, a big effort has still to be done to enhance the protective efficacy of subunit vaccines by the oral route

Estimating the probability of polyreactive antibodies 4E10 and 2F5 disabling a gp41 trimer after T cell-HIV adhesion.

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Bin Hu

2014-01-01

Full Text Available A few broadly neutralizing antibodies, isolated from HIV-1 infected individuals, recognize epitopes in the membrane proximal external region (MPER of gp41 that are transiently exposed during viral entry. The best characterized, 4E10 and 2F5, are polyreactive, binding to the viral membrane and their epitopes in the MPER. We present a model to calculate, for any antibody concentration, the probability that during the pre-hairpin intermediate, the transient period when the epitopes are first exposed, a bound antibody will disable a trivalent gp41 before fusion is complete. When 4E10 or 2F5 bind to the MPER, a conformational change is induced that results in a stably bound complex. The model predicts that for these antibodies to be effective at neutralization, the time to disable an epitope must be shorter than the time the antibody remains bound in this conformation, about five minutes or less for 4E10 and 2F5. We investigate the role of avidity in neutralization and show that 2F5 IgG, but not 4E10, is much more effective at neutralization than its Fab fragment. We attribute this to 2F5 interacting more stably than 4E10 with the viral membrane. We use the model to elucidate the parameters that determine the ability of these antibodies to disable epitopes and propose an extension of the model to analyze neutralization data. The extended model predicts the dependencies of IC50 for neutralization on the rate constants that characterize antibody binding, the rate of fusion of gp41, and the number of gp41 bridging the virus and target cell at the start of the pre-hairpin intermediate. Analysis of neutralization experiments indicate that only a small number of gp41 bridges must be disabled to prevent fusion. However, the model cannot determine the exact number from neutralization experiments alone.

A novel monoclonal antibody targeting carboxymethyllysine, an advanced glycation end product in atherosclerosis and pancreatic cancer.

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Ulrika Wendel

Full Text Available Advanced glycation end products are formed by non-enzymatic reactions between proteins and carbohydrates, causing irreversible lysine and arginine alterations that severely affect protein structure and function. The resulting modifications induce inflammation by binding to scavenger receptors. An increase in advanced glycation end products is observed in a number of diseases e.g. atherosclerosis and cancer. Since advanced glycation end products also are present in healthy individuals, their detection and quantification are of great importance for usage as potential biomarkers. Current methods for advanced glycation end product detection are though limited and solely measure total glycation. This study describes a new epitope-mapped single chain variable fragment, D1-B2, against carboxymethyllysine, produced from a phage library that was constructed from mouse immunizations. The phage library was selected against advanced glycation end product targets using a phage display platform. Characterization of its binding pattern was performed using large synthetic glycated peptide and protein libraries displayed on microarray slides. D1-B2 showed a preference for an aspartic acid, three positions N-terminally from a carboxymethyllysine residue and also bound to a broad collection of glycated proteins. Positive immunohistochemical staining of mouse atherosclerotic plaques and of a tissue microarray of human pancreatic tumors confirmed the usability of the new scFv for advanced glycation end product detection in tissues. This study demonstrates a promising methodology for high-throughput generation of epitope-mapped monoclonal antibodies against AGE.

Epitope selection from an uncensored peptide library displayed on avian leukosis virus

International Nuclear Information System (INIS)

Khare, Pranay D.; Rosales, Ana G.; Bailey, Kent R.; Russell, Stephen J.; Federspiel, Mark J.

2003-01-01

Phage display libraries have provided an extraordinarily versatile technology to facilitate the isolation of peptides, growth factors, single chain antibodies, and enzymes with desired binding specificities or enzymatic activities. The overall diversity of peptides in phage display libraries can be significantly limited by Escherichia coli protein folding and processing machinery, which result in sequence censorship. To achieve an optimal diversity of displayed eukaryotic peptides, the library should be produced in the endoplasmic reticulum of eukaryotic cells using a eukaryotic display platform. In the accompanying article, we presented experiments that demonstrate that polypeptides of various sizes could be efficiently displayed on the envelope glycoproteins of a eukaryotic virus, avian leukosis virus (ALV), and the displayed polypeptides could efficiently attach to cognate receptors without interfering with viral attachment and entry into susceptible cells. In this study, methods were developed to construct a model library of randomized eight amino acid peptides using the ALV eukaryotic display platform and screen the library for specific epitopes using immobilized antibodies. A virus library with approximately 2 x 10 6 different members was generated from a plasmid library of approximately 5 x 10 6 diversity. The sequences of the randomized 24 nucleotide/eight amino acid regions of representatives of the plasmid and virus libraries were analyzed. No significant sequence censorship was observed in producing the virus display library from the plasmid library. Different populations of peptide epitopes were selected from the virus library when different monoclonal antibodies were used as the target. The results of these two studies clearly demonstrate the potential of ALV as a eukaryotic platform for the display and selection of eukaryotic polypeptides libraries

Microarray glycan profiling reveals algal fucoidan epitopes in diverse marine metazoans

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Asunción Salmeán, Armando; Hervé, Cécile; Jørgensen, Bodil

2017-01-01

Despite the biological importance and pharmacological potential of glycans from marine organisms, there are many unanswered questions regarding their distribution, function, and evolution. Here we describe microarray-based glycan profiling of a diverse selection of marine animals using antibodies...... raised against fucoidan isolated from a brown alga. We demonstrate the presence of two fucoidan epitopes in six animals belonging to three phyla including Porifera, Molusca, and Chordata. We studied the spatial distribution of these epitopes in Cliona celata ("boring sponge") and identified...

Structural basis for the binding of the neutralizing antibody, 7D11, to the poxvirus L1 protein

International Nuclear Information System (INIS)

Su, Hua-Poo; Golden, Joseph W.; Gittis, Apostolos G.; Hooper, Jay W.; Garboczi, David N.

2007-01-01

Medical countermeasures to prevent or treat smallpox are needed due to the potential use of poxviruses as biological weapons. Safety concerns with the currently available smallpox vaccine indicate a need for research on alternative poxvirus vaccine strategies. Molecular vaccines involving the use of proteins and/or genes and recombinant antibodies are among the strategies under current investigation. The poxvirus L1 protein, encoded by the L1R open reading frame, is the target of neutralizing antibodies and has been successfully used as a component of both protein subunit and DNA vaccines. L1-specific monoclonal antibodies (e.g., mouse monoclonal antibody mAb-7D11, mAb-10F5) with potent neutralizing activity bind L1 in a conformation-specific manner. This suggests that proper folding of the L1 protein used in molecular vaccines will affect the production of neutralizing antibodies and protection. Here, we co-crystallized the Fab fragment of mAb-7D11 with the L1 protein. The crystal structure of the complex between Fab-7D11 and L1 reveals the basis for the conformation-specific binding as recognition of a discontinuous epitope containing two loops that are held together by a disulfide bond. The structure of this important conformational epitope of L1 will contribute to the development of molecular poxvirus vaccines and also provides a novel target for anti-poxvirus drugs. In addition, the sequence and structure of Fab-7D11 will contribute to the development of L1-targeted immunotherapeutics

Mapping of epitopes on Poa p I and Lol p I allergens with monoclonal antibodies.

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Lin, Z W; Ekramoddoullah, A K; Jaggi, K S; Dzuba-Fischer, J; Rector, E; Kisil, F T

1990-01-01

Allergen Poa p I isolated from the dialysed aqueous extract of Kentucky blue grass pollen by affinity chromatography with an anti-Lol p I murine monoclonal antibody (MAb) 290A-167 was previously shown to consist of a 35.8-kilodalton (kD) component with a pI of 6.4, designated as Poa p Ia, and a 33-kD component with a pI of 9.1, designated as Poa p Ib. The present study reports on the comparative antigenic analyses of these two components, using MAbs produced separately against Poa p I and Lol p I. Thus, anti-Poa p I MAbs 60 and 61 and anti-Lol p I MAb 290A-167 recognized Poa p Ia and Poa p Ib whereas anti-Poa p I MAbs 62, 63 and 64 and anti-Lol p I MAb 348A-6 recognized only Poa p Ia. The specificities of the MAbs were further resolved by comparing their respective abilities to inhibit the binding of 125I-Poa p I or 125I-Lol p I to the different MAbs prepared in the form of solid phase. These studies revealed that at least 4 distinct epitopes (designated as E1, E2, E3 and E4) were shared by both Poa p I and Lol p I. All 4 epitopes were present on Poa p Ia whereas only E1 and E3 were detected on Poa p Ib. E1 was recognized by MAbs 60 and 61, E2 by MAbs 62, 63 and 64, E3 by MAb 290A-167 and E4 by MAb 348A-6.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracellular Targeting of CEA Results in Th1-Type Antibody Responses Following Intradermal Genetic Vaccination by a Needle-Free Jet Injection Device

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Susanne Johansson

2007-01-01

Full Text Available The route and method of immunization, as well as the cellular localization of the antigen, can influence the generation of an immune response. In general, intramuscular immunization results in Th1 responses, whereas intradermal delivery of DNA by gene gun immunization often results in more Th2 responses. Here we investigate how altering the cellular localization of the tumor antigen CEA (carcinoembryonic antigen affects the quality and amplitude of DNA vaccine-induced antibody responses in mice following intradermal delivery of DNA by a needle-free jet injection device (Biojector. CEA was expressed either in a membrane-bound form (wild-type CEA or in two truncated forms (CEA6 and CEA66 with cytoplasmic localization, where CEA66 was fused to a promiscuous T-helper epitope from tetanus toxin. Repeated intradermal immunization of BALB/c mice with DNA encoding wild-type CEA produced high antibody titers of a mixed IgG1/IgG2a ratio. In contrast, utilizing the DNA construct that resulted in intracellular targeting of CEA led to a reduced capacity to induce CEA-specific antibodies, but instead induced a Th1-biased immune response.

Contribution of peptide backbone to Anti-citrulline-dependent antibody reactivity

DEFF Research Database (Denmark)

Trier, Nicole Hartwig; Dam, Catharina; Olsen, Dorthe

2015-01-01

for ACPA reactivity and to be cross-reactive between the selected citrullinated peptides. The remaining amino acids within the citrullinated peptides were found to be of less importance for antibody reactivity. Moreover, these findings indicated that the Cit-Gly motif in combination with peptide backbone...... found in up to 70% of RA patients’ sera, have received much attention. Several citrullinated proteins are associated with RA, suggesting that ACPAs may react with different sequence patterns, separating them from traditional antibodies, whose reactivity usually is specific towards a single target...... homology rather than sequence homology are favored between citrullinated epitopes. These findings are important in relation to clarifying the etiology of RA and to determine the nature of ACPAs, e.g. why some Cit-Gly-containing sequences are not targeted by ACPAs....

Identification of B- and T-cell epitopes from glycoprotein B of herpes simplex virus 2 and evaluation of their immunogenicity and protection efficacy.

Science.gov (United States)

Liu, Kun; Jiang, Deyu; Zhang, Liangyan; Yao, Zhidong; Chen, Zhongwei; Yu, Sanke; Wang, Xiliang

2012-04-19

Herpes simplex virus (HSV) infection is a major health concern worldwide. Evidence obtained from animals and humans indicates that B- and T-cell responses contribute to protective immunity against herpes virus infection. Glycoprotein B is a transmembrane envelope component of HSV-1 and HSV-2, which plays an important role in virion morphogenesis and penetration into host cells, and can induce neutralizing antibodies and protective T-cell response when it is used to immunize humans and animals. However, little is known about gB epitopes that are involved in B- and T-cell activities in vitro and in vivo. Thus, the HSV-2 gB sequence was screened using B- and T-cell epitope prediction systems, and the B-cell regions and the HLA-A*0201-restricted epitopes were identified. These B-cell epitopes elicited high IgG antibody titers in Balb/C mice, with a predominantly IgG1 subclass distribution, which indicated a Th2 bias. Specific IgGs induced by these two epitopes were evaluated as the neutralizing antibodies for virus neutralization. The predicted T-cell epitopes stabilized the HLA-A*0201 molecules on T(2) cells, and stimulate interferon-γ-secreting and cytotoxic CD8(+) T cells. Immunization with the predicted peptides reduced virus shedding and protected against lethal viral challenge in mice. The functional epitopes described herein, both B- and T-cell epitopes, are potentially implicated in vaccine development. Copyright © 2012. Published by Elsevier Ltd.

Mast Cells Produce a Unique Chondroitin Sulfate Epitope.

Science.gov (United States)

Farrugia, Brooke L; Whitelock, John M; O'Grady, Robert; Caterson, Bruce; Lord, Megan S

2016-02-01

The granules of mast cells contain a myriad of mediators that are stored and protected by the sulfated glycosaminoglycan (GAG) chains that decorate proteoglycans. Whereas heparin is the GAG predominantly associated with mast cells, mast cell proteoglycans are also decorated with heparan sulfate and chondroitin sulfate (CS). This study investigated a unique CS structure produced by mast cells that was detected with the antibody clone 2B6 in the absence of chondroitinase ABC digestion. Mast cells in rodent tissue sections were characterized using toluidine blue, Leder stain and the presence of mast cell tryptase. The novel CS epitope was identified in rodent tissue sections and localized to cells that were morphologically similar to cells chemically identified as mast cells. The rodent mast cell-like line RBL-2H3 was also shown to express the novel CS epitope. This epitope co-localized with multiple CS proteoglycans in both rodent tissue and RBL-2H3 cultured cells. These findings suggest that the novel CS epitope that decorates mast cell proteoglycans may play a role in the way these chains are structured in mast cells. © 2016 The Histochemical Society.

First clinical use of ofatumumab, a novel fully human anti-CD20 monoclonal antibody in relapsed or refractory follicular lymphoma

DEFF Research Database (Denmark)

Hagenbeek, Anton; Gadeberg, Ole Vestergaard; Johnson, Peter

2008-01-01

Ofatumumab is a unique monoclonal antibody that targets a distinct small loop epitope on the CD20 molecule. Preclinical data show that ofatumumab is active against B-cell lymphoma/chronic lymphocytic leukemia cells with low CD20-antigen density and high expression of complement inhibitory molecules...

Cross-recognition of a pit viper (Crotalinae) polyspecific antivenom explored through high-density peptide microarray epitope mapping

DEFF Research Database (Denmark)

Engmark, Mikael; Lomonte, Bruno; Gutiérrez, José María

2017-01-01

Snakebite antivenom is a 120 years old invention based on polyclonal mixtures of antibodies purified from the blood of hyper-immunized animals. Knowledge on antibody recognition sites (epitopes) on snake venom proteins is limited, but may be used to provide molecular level explanations...... for antivenom cross-reactivity. In turn, this may help guide antivenom development by elucidating immunological biases in existing antivenoms. In this study, we have identified and characterized linear elements of B-cell epitopes from 870 pit viper venom protein sequences by employing a high......-throughput methodology based on custom designed high-density peptide microarrays. By combining data on antibody-peptide interactions with multiple sequence alignments of homologous toxin sequences and protein modelling, we have determined linear elements of antibody binding sites for snake venom metalloproteases (SVMPs...

Identification of a conformational neutralizing epitope on the VP1 protein of type A foot-and-mouth disease virus.

Science.gov (United States)

Liu, Wenming; Yang, Baolin; Wang, Mingxia; Wang, Haiwei; Yang, Decheng; Ma, Wenge; Zhou, Guohui; Yu, Li

2017-12-01

Foot-and-mouth disease (FMD) caused by foot-and-mouth disease virus (FMDV), is a highly contagious infectious disease that affects domestic and wild cloven-hoofed animals worldwide. In recent years, outbreaks of serotype A FMD have occurred in many countries. High-affinity neutralizing antibodies against a conserved epitope could provide protective immunity against diverse subtypes of FMDV serotype A and protect against future pandemics. In this study, we generated a serotype A FMDV-specific potent neutralizing monoclonal antibody (MAb), 6C9, which recognizes a conformation-dependent epitope. MAb 6C9 potently neutralized FMDV A/XJBC/CHA/2010 with a 50% neutralization titer (NT 50 ) of 4096. Screening of a phage-displayed random 12-mer peptide library revealed that MAb 6C9 bound to phages displaying the consensus motif YxxPxGDLG, which is highly homologous to the 135 YxxPxxxxxGDLG 147 motif found in the serotype A FMDV virus-encoded structural protein VP1. To further verify the authentic epitope recognized by MAb 6C9, two FMDV A/XJBC/CHA/2010 mutant viruses, P138A and G144A, were generated using a reverse genetic system. Subsequent micro-neutralization assays and double-antibody sandwich (DAS) ELISA analyses revealed that the Pro 138 and Gly 144 residues of the conformational epitope that are recognized by 6C9 are important for MAb 6C9 binding. Importantly, the epitope 135 YxxPxxxxxGDLG 147 was highly conserved among different topotypes of serotype A FMDV strains in a sequence alignment analysis. Thus, the results of this study could have potential applications in the development of novel epitope-based vaccines and suitable a MAb-based diagnostic method for the detection of serotype A FMDV and the quantitation of antibodies against this serotype. Copyright © 2017 Elsevier Ltd. All rights reserved.

Some epitopes conservation in non structural 3 protein dengue virus serotype 4

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Tegar A. P. Siregar

2016-03-01

Full Text Available AbstrakLatar belakang: Protein Non Struktural 3 (NS3 virus dengue menginduksi respon antibodi netralisasidan respon sel T CD4+ dan CD8+, serta berperan dalam replikasi virus. Protein NS3 memiliki epitopepitopsel T dan B yang terdapat perbedaan kelestarian pada berbagai strain virus dengue serotipe 4(DENV-4. Penelitian ini bertujuan untuk mengetahui kelestarian epitop sel T dan B pada protein NS3DENV-4 strain-strain dunia dan keempat serotipe virus dengue strain Indonesia.Metode: Penelitian ini dilakukan di Departemen Mikrobiologi Fakultas Kedokteran UI sejak Juni 2013 - April2014. Sekuens asam amino NS3 DENV-4 strain 081 didapatkan setelah produk PCR gen NS3 DENV-4 081disekuensing. Epitop-epitop sel T dan sel B protein NS3 DENV-4 081 dianalisis dan dibandingkan dengansekuens asam amino protein NS3 dari 124 strain DENV-4 di dunia dan keempat serotipe DENV strain Indonesia.Strain-strain dunia merupakan strain yang ada di benua Amerika (Venezuela, Colombia, dll dan Asia (Cina,Singapura, dll. Referensi posisi epitop sel T dan B protein NS3 diperoleh dari laporan penelitian terdahulu.Hasil: Delapan epitop sel T dan 2 epitop sel B dari protein NS3 DENV-4 081 ternyata identik dan lestaripada protein NS3 dari 124 strain DENV-4 dunia. Epitop sel B di posisi asam amino 537-544 pada proteinNS3 DENV-4 081 ternyata identik dan lestari dengan epitop sel B protein NS3 dari keempat serotipeDENV strain Indonesia.Kesimpulan: Kelestarian yang luas dari epitop sel T dan B pada hampir seluruh strain DENV-4 dunia danserotipe-serotipe DENV strain Indonesia. (Health Science Journal of Indonesia 2015;6:126-31Kata kunci: virus dengue, protein NS3, epitop sel T, epitop sel B AbstractBackground: Non Structural 3 (NS3 protein of dengue virus (DENV is known to induce antibody, CD4+and CD8+ T cell responses, and playing role in viral replication. NS3 protein has T and B cell epitopes,which has conservation difference between DENV-4 strains. This study aimed to identify

Novel anti-HER2 monoclonal antibodies: synergy and antagonism with tumor necrosis factor-α

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Ceran Ceyhan

2012-10-01

Full Text Available Abstract Background One-third of breast cancers display amplifications of the ERBB2 gene encoding the HER2 kinase receptor. Trastuzumab, a humanized antibody directed against an epitope on subdomain IV of the extracellular domain of HER2 is used for therapy of HER2-overexpressing mammary tumors. However, many tumors are either natively resistant or acquire resistance against Trastuzumab. Antibodies directed to different epitopes on the extracellular domain of HER2 are promising candidates for replacement or combinatorial therapy. For example, Pertuzumab that binds to subdomain II of HER2 extracellular domain and inhibits receptor dimerization is under clinical trial. Alternative antibodies directed to novel HER2 epitopes may serve as additional tools for breast cancer therapy. Our aim was to generate novel anti-HER2 monoclonal antibodies inhibiting the growth of breast cancer cells, either alone or in combination with tumor necrosis factor-α (TNF-α. Methods Mice were immunized against SK-BR-3 cells and recombinant HER2 extracellular domain protein to produce monoclonal antibodies. Anti-HER2 antibodies were characterized with breast cancer cell lines using immunofluorescence, flow cytometry, immunoprecipitation, western blot techniques. Antibody epitopes were localized using plasmids encoding recombinant HER2 protein variants. Antibodies, either alone or in combination with TNF-α, were tested for their effects on breast cancer cell proliferation. Results We produced five new anti-HER2 monoclonal antibodies, all directed against conformational epitope or epitopes restricted to the native form of the extracellular domain. When tested alone, some antibodies inhibited modestly but significantly the growth of SK-BR-3, BT-474 and MDA-MB-361 cells displaying ERBB2 amplification. They had no detectable effect on MCF-7 and T47D cells lacking ERBB2 amplification. When tested in combination with TNF-α, antibodies acted synergistically on SK-BR-3 cells

Cross-Reactivity of Polyclonal Antibodies against Canavalia ensiformis (Jack Bean) Urease and Helicobacter pylori Urease Subunit A Fragments.

Science.gov (United States)

Kaminski, Zbigniew Jerzy; Relich, Inga; Konieczna, Iwona; Kaca, Wieslaw; Kolesinska, Beata

2018-01-01

Overlapping decapeptide fragments of H. pylori urease subunit A (UreA) were synthesized and tested with polyclonal antibodies against Canavalia ensiformis (Jack bean) urease. The linear epitopes of UreA identified using the dot blot method were then examined using epitope mapping. For this purpose, series of overlapping fragments of UreA, frameshifted ± four amino acid residues were synthesized. Most of the UreA epitopes which reacted with the Jack bean urease polyclonal antibodies had been recognized in previous studies by monoclonal antibodies against H. pylori urease. Fragments 11 - 24, 21 - 33, and 31 - 42 were able to interact with the Jack bean urease antibodies, giving stable immunological complexes. However, the lack of recognition by these antibodies of all the components in the peptide map strongly suggests that a non-continuous (nonlinear) epitope is located on the N-terminal domain of UreA. © 2018 Wiley-VHCA AG, Zurich, Switzerland.

Importance of Neutralizing Monoclonal Antibodies Targeting Multiple Antigenic Sites on the Middle East Respiratory Syndrome Coronavirus Spike Glycoprotein To Avoid Neutralization Escape

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Wang, Lingshu; Shi, Wei; Chappell, James D.; Joyce, M. Gordon; Zhang, Yi; Kanekiyo, Masaru; Becker, Michelle M.; van Doremalen, Neeltje; Fischer, Robert; Wang, Nianshuang; Corbett, Kizzmekia S.; Choe, Misook; Mason, Rosemarie D.; Van Galen, Joseph G.; Zhou, Tongqing; Saunders, Kevin O.; Tatti, Kathleen M.; Haynes, Lia M.; Kwong, Peter D.; Modjarrad, Kayvon; Kong, Wing-Pui; McLellan, Jason S.; Denison, Mark R.; Munster, Vincent J.; Mascola, John R.; Graham, Barney S.; Gallagher, Tom

2018-03-07

structurally defined probes for the MERS-CoV spike glycoprotein (S), the target for neutralizing antibodies, single B cells were sorted from a convalescent human and immunized nonhuman primates (NHPs). MAbs produced from paired immunoglobulin gene sequences were mapped to multiple epitopes within and outside the receptor-binding domain (RBD) and protected against lethal MERS infection in a murine model following passive immunization. Importantly, combining MAbs targeting distinct epitopes prevented viral neutralization escape from RBD-directed MAbs. These data suggest that antibody responses to multiple domains on CoV spike protein may improve immunity and will guide future vaccine and therapeutic development efforts.

Vaccine Targeting of Subdominant CD8+ T Cell Epitopes Increases the Breadth of the T Cell Response upon Viral Challenge, but May Impair Immediate Virus Control

DEFF Research Database (Denmark)

Steffensen, Maria A; Pedersen, Louise Holm; Jahn, Marie Louise

2016-01-01

As a result of the difficulties in making efficient vaccines against genetically unstable viruses such as HIV, it has been suggested that future vaccines should preferentially target subdominant epitopes, the idea being that this should allow a greater breadth of the induced T cell response and, ...... a limitation of our model, but clearly our findings underscore the importance of carefully weighing the pros and cons of changes in epitope targeting before any implementation.......As a result of the difficulties in making efficient vaccines against genetically unstable viruses such as HIV, it has been suggested that future vaccines should preferentially target subdominant epitopes, the idea being that this should allow a greater breadth of the induced T cell response and......, hence, a greater efficiency in controlling escape variants. However, to our knowledge the evidence supporting this concept is limited at best. To improve upon this, we used the murine lymphocytic choriomeningitis virus model and adenoviral vectors to compare a vaccine expressing unmodified Ag...

High-throughput epitope profiling of snake venom toxins

DEFF Research Database (Denmark)

Engmark, Mikael; Andersen, Mikael Rørdam; Laustsen, Andreas Hougaard

Insight into the molecular details of polyclonal antivenom antibody specificity is a prerequisite for accurate prediction of cross-reactivity and can provide a basis for design of novel antivenoms. In this work, a highthroughput approach was applied to characterize linear elements in epitopes in ...... toxins from four African mamba and three neurotoxic cobra snakes obtained from public databases....

A Cross-Reactive Human Single-Chain Antibody for Detection of Major Fish Allergens, Parvalbumins, and Identification of a Major IgE-Binding Epitope.

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Merima Bublin

Full Text Available Fish allergy is associated with moderate to severe IgE-mediated reactions to the calcium binding parvalbumins present in fish muscle. Allergy to multiple fish species is caused by parvalbumin-specific cross-reactive IgE recognizing conserved epitopes. In this study, we aimed to produce cross-reactive single chain variable fragment (scFv antibodies for the detection of parvalbumins in fish extracts and the identification of IgE epitopes. Parvalbumin-specific phage clones were isolated from the human ETH-2 phage display library by three rounds of biopanning either against cod parvalbumin or by sequential biopanning against cod (Gad m 1, carp (Cyp c 1 and rainbow trout (Onc m 1 parvalbumins. While biopanning against Gad m 1 resulted in the selection of clones specific exclusively for Gad m 1, the second approach resulted in the selection of clones cross-reacting with all three parvalbumins. Two clones, scFv-gco9 recognizing all three parvalbumins, and scFv-goo8 recognizing only Gad m 1 were expressed in the E. coli non-suppressor strain HB2151 and purified from the periplasm. scFv-gco9 showed highly selective binding to parvalbumins in processed fish products such as breaded cod sticks, fried carp and smoked trout in Western blots. In addition, the scFv-gco9-AP produced as alkaline phosphatase fusion protein, allowed a single-step detection of the parvalbumins. In competitive ELISA, scFv-gco9 was able to inhibit binding of IgE from fish allergic patients' sera to all three β-parvalbumins by up to 80%, whereas inhibition by scFv-goo8 was up to 20%. 1H/15N HSQC NMR analysis of the rGad m 1:scFv-gco9 complex showed participation of amino acid residues conserved among these three parvalbumins explaining their cross-reactivity on a molecular level. In this study, we have demonstrated an approach for the selection of cross-reactive parvalbumin-specific antibodies that can be used for allergen detection and for mapping of conserved epitopes.

A Cross-Reactive Human Single-Chain Antibody for Detection of Major Fish Allergens, Parvalbumins, and Identification of a Major IgE-Binding Epitope.

Science.gov (United States)

Bublin, Merima; Kostadinova, Maria; Fuchs, Julian E; Ackerbauer, Daniela; Moraes, Adolfo H; Almeida, Fabio C L; Lengger, Nina; Hafner, Christine; Ebner, Christof; Radauer, Christian; Liedl, Klaus R; Valente, Ana Paula; Breiteneder, Heimo

2015-01-01

Fish allergy is associated with moderate to severe IgE-mediated reactions to the calcium binding parvalbumins present in fish muscle. Allergy to multiple fish species is caused by parvalbumin-specific cross-reactive IgE recognizing conserved epitopes. In this study, we aimed to produce cross-reactive single chain variable fragment (scFv) antibodies for the detection of parvalbumins in fish extracts and the identification of IgE epitopes. Parvalbumin-specific phage clones were isolated from the human ETH-2 phage display library by three rounds of biopanning either against cod parvalbumin or by sequential biopanning against cod (Gad m 1), carp (Cyp c 1) and rainbow trout (Onc m 1) parvalbumins. While biopanning against Gad m 1 resulted in the selection of clones specific exclusively for Gad m 1, the second approach resulted in the selection of clones cross-reacting with all three parvalbumins. Two clones, scFv-gco9 recognizing all three parvalbumins, and scFv-goo8 recognizing only Gad m 1 were expressed in the E. coli non-suppressor strain HB2151 and purified from the periplasm. scFv-gco9 showed highly selective binding to parvalbumins in processed fish products such as breaded cod sticks, fried carp and smoked trout in Western blots. In addition, the scFv-gco9-AP produced as alkaline phosphatase fusion protein, allowed a single-step detection of the parvalbumins. In competitive ELISA, scFv-gco9 was able to inhibit binding of IgE from fish allergic patients' sera to all three β-parvalbumins by up to 80%, whereas inhibition by scFv-goo8 was up to 20%. 1H/15N HSQC NMR analysis of the rGad m 1:scFv-gco9 complex showed participation of amino acid residues conserved among these three parvalbumins explaining their cross-reactivity on a molecular level. In this study, we have demonstrated an approach for the selection of cross-reactive parvalbumin-specific antibodies that can be used for allergen detection and for mapping of conserved epitopes.

Study of the epitope structure of purified Dac G I and Lol p I, the major allergens of Dactylis glomerata and Lolium perenne pollens, using monoclonal antibodies.

Science.gov (United States)

Mourad, W; Mécheri, S; Peltre, G; David, B; Hébert, J

1988-11-15

The use of mAb allowed us to further analyze the cross-reactivity between purified Dac g I and Lol p I, the major allergens of Dactylis glomerata (cocksfoot) and Lolium perenne (Rye grass), respectively. It was first shown, using IEF, followed by immunoprinting, that serum IgE antibodies from most grass-sensitive patients recognize both Dac g I and Lol p I. Second, three different anti-Lol p I mAb, 290A-167, 348A-6, and 539A-6, and one anti-Dac g I mAb, P3B2 were all shown to react with Dac g I and Lol p I, indicating that the two molecules share common epitopes. Epitope specificity of the mAb was determined by competitive binding inhibition of a given labeled mAb to solid phase fixed Dac g I or Lol p I by the mAb. The results indicated that the four mAb are directed against four different and non-overlapping epitopes present on both allergens. Using double-binding RIA, our data strongly suggest that the common epitopes are not repetitive on both molecules. In addition to their similar physicochemical characteristics, such as isolectric points and m.w., Dac g I and Lol p I share four identical epitopes. Binding inhibition of human IgE to Lol p I and Dac g I by the mAb was also assessed. The results indicated that each mAb was able to inhibit such reactions to variable degree but no additive inhibition was observed when two mAb of different specificities were used in combination, suggesting that the human IgE binding site is partially shared by each epitope recognized by the four mAb.

Generation of a novel high-affinity monoclonal antibody with conformational recognition epitope on human IgM.

Science.gov (United States)

Sarikhani, Sina; Mirshahi, Manouchehr; Gharaati, Mohammad Reza; Mirshahi, Tooran

2010-11-01

As IgM is the first isotype of antibody which appears in blood after initial exposure to a foreign antigen in the pattern of primary response, detection, and quantification of this molecule in blood seems invaluable. To approach these goals, generation, and characterization of a highly specific mAb (monoclonal antibody) against human IgM were investigated. Human IgM immunoglobulins were used to immunize Balb/c mice. Spleen cells taken from the immunized animals were fused with SP2/O myeloma cells using PEG (polyethylene glycol, MW 1450) as fusogen. The hybridomas were cultured in HAT containing medium and supernatants from the growing hybrids were screened by enzyme-linked immunosorbent assay (ELISA) using plates coated with pure human IgM and the positive wells were then cloned at limiting dilutions. The best clone designated as MAN-1, was injected intraperitoneally to some Pristane-injected mice. Anti-IgM mAb was purified from the animals' ascitic fluid by protein-G sepharose followed by DEAE-cellulose ion exchange chromatography. MAN-1 interacted with human IgM with a very high specificity and affinity. The purity of the sample was tested by SDS-PAGE and the affinity constant was measured (K(a) = 3.5 x 10(9)M(-1). Immunoblotting and competitive ELISA were done and the results showed that the harvested antibody recognizes a conformational epitope on the mu chain of human IgM and there was no cross-reactivity with other subclasses of immunoglobulins. Furthermore, isotyping test was done and the results showed the subclass of the obtained mAb which was IgG(1)kappa.

Inhibition of human immunodeficiency virus (HIV) infection in vitro by anticarbohydrate monoclonal antibodies: peripheral glycosylation of HIV envelope glycoprotein gp120 may be a target for virus neutralization

DEFF Research Database (Denmark)

Hansen, J E; Clausen, H; Nielsen, C

1990-01-01

Carbohydrate structures are often involved in the initial adhesion of pathogens to target cells. In the present study, a panel of anticarbohydrate monoclonal antibodies (MAbs) was tested for their ability to inhibit in vitro human immunodeficiency virus infectivity. MAbs against three different N......- and O-linked carbohydrate epitopes (LeY, A1, and sialyl-Tn) were able to block infection by cell-free virus as well as inhibit syncytium formation. Inhibition of virus infectivity was independent of virus strain (HTLVIIIB or patient isolate SSI-002), the cell line used for virus propagation (H9 or MT4...

Development of novel monoclonal antibodies against starch and ulvan - Implications for antibody production against polysaccharides with limited immunogenicity

DEFF Research Database (Denmark)

Rydahl, Maja Gro; Kračun, Stjepan K.; Fangel, Jonatan U.

2017-01-01

Monoclonal antibodies (mAbs) are widely used and powerful research tools, but the generation of mAbs against glycan epitopes is generally more problematic than against proteins. This is especially significant for research on polysaccharide-rich land plants and algae (Viridiplantae). Most antibody...

EPMLR: sequence-based linear B-cell epitope prediction method using multiple linear regression.

Science.gov (United States)

Lian, Yao; Ge, Meng; Pan, Xian-Ming

2014-12-19

B-cell epitopes have been studied extensively due to their immunological applications, such as peptide-based vaccine development, antibody production, and disease diagnosis and therapy. Despite several decades of research, the accurate prediction of linear B-cell epitopes has remained a challenging task. In this work, based on the antigen's primary sequence information, a novel linear B-cell epitope prediction model was developed using the multiple linear regression (MLR). A 10-fold cross-validation test on a large non-redundant dataset was performed to evaluate the performance of our model. To alleviate the problem caused by the noise of negative dataset, 300 experiments utilizing 300 sub-datasets were performed. We achieved overall sensitivity of 81.8%, precision of 64.1% and area under the receiver operating characteristic curve (AUC) of 0.728. We have presented a reliable method for the identification of linear B cell epitope using antigen's primary sequence information. Moreover, a web server EPMLR has been developed for linear B-cell epitope prediction: http://www.bioinfo.tsinghua.edu.cn/epitope/EPMLR/ .

B and T Cell Epitope-Based Peptides Predicted from Evolutionarily Conserved and Whole Protein Sequences of Ebola Virus as Vaccine Targets.

Science.gov (United States)

Yasmin, T; Nabi, A H M Nurun

2016-05-01

Ebola virus (EBV) has become a serious threat to public health. Different approaches were applied to predict continuous and discontinuous B cell epitopes as well as T cell epitopes from the sequence-based and available three-dimensional structural analyses of each protein of EBV. Peptides '(79) VPSATKRWGFRSGVPP(94) ' from GP1 and '(515) LHYWTTQDEGAAIGLA(530) ' from GP2 of Ebola were found to be the consensus peptidic sequences predicted as linear B cell epitope of which the latter contains a region (519) TTQDEG(524) that fulfilled all the criteria of accessibility, hydrophilicity, flexibility and beta turn region for becoming an ideal B cell epitope. Different nonamers as T cell epitopes were obtained that interacted with different numbers of MHC class I and class II alleles with a binding affinity of <100 nm. Interestingly, these alleles also bound to the MHC class I alleles mostly prevalent in African and South Asian regions. Of these, 'LANETTQAL' and 'FLYDRLAST' nonamers were predicted to be the most potent T cell epitopes and they, respectively, interacted with eight and twelve class I alleles that covered 63.79% and 54.16% of world population, respectively. These nonamers were found to be the core sequences of 15mer peptides that interacted with the most common class II allele, HLA-DRB1*01:01. They were further validated for their binding to specific class I alleles using docking technique. Thus, these predicted epitopes may be used as vaccine targets against EBV and can be validated in model hosts to verify their efficacy as vaccine. © 2016 The Foundation for the Scandinavian Journal of Immunology.

Characterization of an Immunodominant Epitope in the Endodomain of the Coronavirus Membrane Protein

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Hui Dong

2016-12-01

Full Text Available The coronavirus membrane (M protein acts as a dominant immunogen and is a major player in virus assembly. In this study, we prepared two monoclonal antibodies (mAbs; 1C3 and 4C7 directed against the transmissible gastroenteritis virus (TGEV M protein. The 1C3 and 4C7 mAbs both reacted with the native TGEV M protein in western blotting and immunofluorescence (IFA assays. Two linear epitopes, 243YSTEART249 (1C3 and 243YSTEARTDNLSEQEKLLHMV262 (4C7, were identified in the endodomain of the TGEV M protein. The 1C3 mAb can be used for the detection of the TGEV M protein in different assays. An IFA method for the detection of TGEV M protein was optimized using mAb 1C3. Furthermore, the ability of the epitope identified in this study to stimulate antibody production was also evaluated. An immunodominant epitope in the TGEV membrane protein endodomain was identified. The results of this study have implications for further research on TGEV replication.

Generation of neutralising antibodies against porcine endogenous retroviruses (PERVs)

International Nuclear Information System (INIS)

Kaulitz, Danny; Fiebig, Uwe; Eschricht, Magdalena; Wurzbacher, Christian; Kurth, Reinhard; Denner, Joachim

2011-01-01

Antibodies neutralising porcine endogenous retroviruses (PERVs) were induced in different animal species by immunisation with the transmembrane envelope protein p15E. These antibodies recognised epitopes, designated E1, in the fusion peptide proximal region (FPPR) of p15E, and E2 in the membrane proximal external region (MPER). E2 is localised in a position similar to that of an epitope in the transmembrane envelope protein gp41 of the human immunodeficiency virus-1 (HIV-1), recognised by the monoclonal antibody 4E10 that is broadly neutralising. To detect neutralising antibodies specific for PERV, a novel assay was developed, which is based on quantification of provirus integration by real-time PCR. In addition, for the first time, highly effective neutralising antibodies were obtained by immunisation with the surface envelope protein of PERV. These data indicate that neutralising antibodies can be induced by immunisation with both envelope proteins.

Molecular definition of multiple sites of antibody inhibition of malaria transmission-blocking vaccine antigen Pfs25.

Science.gov (United States)

Scally, Stephen W; McLeod, Brandon; Bosch, Alexandre; Miura, Kazutoyo; Liang, Qi; Carroll, Sean; Reponen, Sini; Nguyen, Ngan; Giladi, Eldar; Rämisch, Sebastian; Yusibov, Vidadi; Bradley, Allan; Lemiale, Franck; Schief, William R; Emerling, Daniel; Kellam, Paul; King, C Richter; Julien, Jean-Philippe

2017-11-16

The Plasmodium falciparum Pfs25 protein (Pfs25) is a leading malaria transmission-blocking vaccine antigen. Pfs25 vaccination is intended to elicit antibodies that inhibit parasite development when ingested by Anopheles mosquitoes during blood meals. The Pfs25 three-dimensional structure has remained elusive, hampering a molecular understanding of its function and limiting immunogen design. We report six crystal structures of Pfs25 in complex with antibodies elicited by immunization via Pfs25 virus-like particles in human immunoglobulin loci transgenic mice. Our structural findings reveal the fine specificities associated with two distinct immunogenic sites on Pfs25. Importantly, one of these sites broadly overlaps with the epitope of the well-known 4B7 mouse antibody, which can be targeted simultaneously by antibodies that target a non-overlapping site to additively increase parasite inhibition. Our molecular characterization of inhibitory antibodies informs on the natural disposition of Pfs25 on the surface of ookinetes and provides the structural blueprints to design next-generation immunogens.

Anaplasma marginale major surface protein 2 CD4+-T-cell epitopes are evenly distributed in conserved and hypervariable regions (HVR), whereas linear B-cell epitopes are predominantly located in the HVR.

Science.gov (United States)

Abbott, Jeffrey R; Palmer, Guy H; Howard, Chris J; Hope, Jayne C; Brown, Wendy C

2004-12-01

Organisms in the genus Anaplasma express an immunodominant major surface protein 2 (MSP2), composed of a central hypervariable region (HVR) flanked by highly conserved regions. Throughout Anaplasma marginale infection, recombination results in the sequential appearance of novel MSP2 variants and subsequent control of rickettsemia by the immune response, leading to persistent infection. To determine whether immune evasion and selection for variant organisms is associated with a predominant response against HVR epitopes, T-cell and linear B-cell epitopes were localized by measuring peripheral blood gamma interferon-secreting cells, proliferation, and antibody binding to 27 overlapping peptides spanning MSP2 in 16 cattle. Similar numbers of MSP2-specific CD4(+) T-cell epitopes eliciting responses of similar magnitude were found in conserved and hypervariable regions. T-cell epitope clusters recognized by the majority of animals were identified in the HVR (amino acids [aa] 171 to 229) and conserved regions (aa 101 to 170 and 272 to 361). In contrast, linear B-cell epitopes were concentrated in the HVR, residing within hydrophilic sequences. The pattern of recognition of epitope clusters by T cells and of HVR epitopes by B cells is consistent with the influence of protein structure on epitope recognition.

Targeting IgG in Arthritis: Disease Pathways and Therapeutic Avenues

Directory of Open Access Journals (Sweden)

Kutty Selva Nandakumar

2018-02-01

Full Text Available Rheumatoid arthritis (RA is a polygenic and multifactorial syndrome. Many complex immunological and genetic interactions are involved in the final outcome of the clinical disease. Autoantibodies (rheumatoid factors, anti-citrullinated peptide/protein antibodies are present in RA patients’ sera for a long time before the onset of clinical disease. Prior to arthritis onset, in the autoantibody response, epitope spreading, avidity maturation, and changes towards a pro-inflammatory Fc glycosylation phenotype occurs. Genetic association of epitope specific autoantibody responses and the induction of inflammation dependent and independent changes in the cartilage by pathogenic autoantibodies emphasize the crucial contribution of antibody-initiated inflammation in RA development. Targeting IgG by glyco-engineering, bacterial enzymes to specifically cleave IgG/alter N-linked Fc-glycans at Asn 297 or blocking the downstream effector pathways offers new avenues to develop novel therapeutics for arthritis treatment.

Native Mass Spectrometry, Ion mobility, and Collision-Induced Unfolding Categorize Malaria Antigen/Antibody Binding

Science.gov (United States)

Huang, Yining; Salinas, Nichole D.; Chen, Edwin; Tolia, Niraj H.; Gross, Michael L.

2017-09-01

Plasmodium vivax Duffy Binding Protein (PvDBP) is a promising vaccine candidate for P. vivax malaria. Recently, we reported the epitopes on PvDBP region II (PvDBP-II) for three inhibitory monoclonal antibodies (2D10, 2H2, and 2C6). In this communication, we describe the combination of native mass spectrometry and ion mobility (IM) with collision induced unfolding (CIU) to study the conformation and stabilities of three malarial antigen-antibody complexes. These complexes, when collisionally activated, undergo conformational changes that depend on the location of the epitope. CIU patterns for PvDBP-II in complex with antibody 2D10 and 2H2 are highly similar, indicating comparable binding topology and stability. A different CIU fingerprint is observed for PvDBP-II/2C6, indicating that 2C6 binds to PvDBP-II on an epitope different from 2D10 and 2H2. This work supports the use of CIU as a means of classifying antigen-antibody complexes by their epitope maps in a high throughput screening workflow. [Figure not available: see fulltext.

Pep-3D-Search: a method for B-cell epitope prediction based on mimotope analysis.

Science.gov (United States)

Huang, Yan Xin; Bao, Yong Li; Guo, Shu Yan; Wang, Yan; Zhou, Chun Guang; Li, Yu Xin

2008-12-16

The prediction of conformational B-cell epitopes is one of the most important goals in immunoinformatics. The solution to this problem, even if approximate, would help in designing experiments to precisely map the residues of interaction between an antigen and an antibody. Consequently, this area of research has received considerable attention from immunologists, structural biologists and computational biologists. Phage-displayed random peptide libraries are powerful tools used to obtain mimotopes that are selected by binding to a given monoclonal antibody (mAb) in a similar way to the native epitope. These mimotopes can be considered as functional epitope mimics. Mimotope analysis based methods can predict not only linear but also conformational epitopes and this has been the focus of much research in recent years. Though some algorithms based on mimotope analysis have been proposed, the precise localization of the interaction site mimicked by the mimotopes is still a challenging task. In this study, we propose a method for B-cell epitope prediction based on mimotope analysis called Pep-3D-Search. Given the 3D structure of an antigen and a set of mimotopes (or a motif sequence derived from the set of mimotopes), Pep-3D-Search can be used in two modes: mimotope or motif. To evaluate the performance of Pep-3D-Search to predict epitopes from a set of mimotopes, 10 epitopes defined by crystallography were compared with the predicted results from a Pep-3D-Search: the average Matthews correlation coefficient (MCC), sensitivity and precision were 0.1758, 0.3642 and 0.6948. Compared with other available prediction algorithms, Pep-3D-Search showed comparable MCC, specificity and precision, and could provide novel, rational results. To verify the capability of Pep-3D-Search to align a motif sequence to a 3D structure for predicting epitopes, 6 test cases were used. The predictive performance of Pep-3D-Search was demonstrated to be superior to that of other similar programs

Chemoradiotherapy of cancer using boronated monoclonal antibodies. Progress report, December 1, 1982-November 30, 1983

International Nuclear Information System (INIS)

Soloway, A.H.

1984-01-01

The feasibility was established of using antibodies for the delivery of 10 B. Problems faced included 1) preservation of antibody activity following boronation, 2) antigenic receptor site density of the target cells, and 3) delivery of a critical number of 10 B atoms per cell. The linkage of a heavily boronated polymeric species to antibody by means of a single functional group allow for the delivery of a large number 10 B atoms per antibody molecule without a significant reduction in affinity. Both the polyclonally derived anti-thymocyte globulin (ATG) and the monoclonal anti-colorectal carcinoma antibody (17-1A) recognize antigens that are expressed with a density of approximately 10 6 epitopes per cell. The major concept that we advance is that just as effective cancer chemotherapy is based on the use of a combination of drugs, similarly a combination of compounds could be employed to deliver the requisite amount of 10 B to tumor target cells. This could include compounds such as Na 2 B 12 H 11 Sh together with boronated antibodies directed against tumor associated antigens. (DT)

Combined roles of human IgG subclass, alternative complement pathway activation, and epitope density in the bactericidal activity of antibodies to meningococcal factor h binding protein.

Science.gov (United States)

Giuntini, Serena; Reason, Donald C; Granoff, Dan M

2012-01-01

Meningococcal vaccines containing factor H binding protein (fHbp) are in clinical development. fHbp binds human fH, which enables the meningococcus to resist complement-mediated bacteriolysis. Previously, we found that chimeric human IgG1 mouse anti-fHbp monoclonal antibodies (MAbs) had human complement-mediated bactericidal activity only if the MAb inhibited fH binding. Since IgG subclasses differ in their ability to activate complement, we investigated the role of human IgG subclasses on antibody functional activity. We constructed chimeric MAbs in which three different murine fHbp-specific binding domains were each paired with human IgG1, IgG2, or IgG3. Against a wild-type group B isolate, all three IgG3 MAbs, irrespective of their ability to inhibit fH binding, had bactericidal activity that was >5-fold higher than the respective IgG1 MAbs, while the IgG2 MAbs had the least activity. Against a mutant with increased fHbp expression, the anti-fHbp MAbs elicited greater C4b deposition (classical pathway) and greater bactericidal activity than against the wild-type strain, and the IgG1 MAbs had similar or greater activity than the respective IgG3 MAbs. The bactericidal activity against both wild-type and mutant strains also was dependent, in part, on activation of the alternative complement pathway. Thus, at lower epitope density in the wild-type strain, the IgG3 anti-fHbp MAbs had the greatest bactericidal activity. At a higher epitope density in the mutant, the IgG1 MAbs had similar or greater bactericidal activity than the IgG3 MAbs, and the activity was less dependent on the inhibition of fH binding than at a lower epitope density.

Laminin binding protein, 34/67 laminin receptor, carries stage-specific embryonic antigen-4 epitope defined by monoclonal antibody Raft.2

International Nuclear Information System (INIS)

Katagiri, Yohko U.; Kiyokawa, Nobutaka; Nakamura, Kyoko; Takenouchi, Hisami; Taguchi, Tomoko; Okita, Hajime; Umezawa, Akihiro; Fujimoto, Junichiro

2005-01-01

We previously produced monoclonal antibodies against the detergent-insoluble microdomain, i.e., the raft microdomain, of the human renal cancer cell line ACHN. Raft.2, one of these monoclonal antibodies, recognizes sialosyl globopentaosylceramide, which has the stage-specific embryonic antigen (SSEA)-4 epitope. Although the mouse embryonal carcinoma (EC) cell line F9 does not express SSEA-4, some F9 cells stained with Raft.2. Western analysis and matrix-assisted laser desorption ionization-time of flight mass spectrometry identified the Raft.2 binding molecule as laminin binding protein (LBP), i.e., 34/67 laminin receptor. Weak acid treatment or digestion with Clostridium perfringens sialidase reduced Raft.2 binding to LBP on nitrocellulose sheets and [ 14 C]galactose was incorporated into LBP, indicating LBP to have a sialylated carbohydrate moiety. Subcellular localization analysis by sucrose density-gradient centrifugation and examination by confocal microscopy revealed LBP to be localized on the outer surface of the plasma membrane. An SSEA-4-positive human EC cell line, NCR-G3 cells, also expressed Raft.2-binding LBP

Developmental Localization and Methylesterification of Pectin Epitopes during Somatic Embryogenesis of Banana (Musa spp. AAA)

Science.gov (United States)

Xu, Chunxiang; Zhao, Lu; Pan, Xiao; Šamaj, Jozef

2011-01-01

Background The plant cell walls play an important role in somatic embryogenesis and plant development. Pectins are major chemical components of primary cell walls while homogalacturonan (HG) is the most abundant pectin polysaccharide. Developmental regulation of HG methyl-esterification degree is important for cell adhesion, division and expansion, and in general for proper organ and plant development. Methodology/Principal Findings Developmental localization of pectic homogalacturonan (HG) epitopes and the (1→4)-β-D-galactan epitope of rhamnogalacturonan I (RG-I) and degree of pectin methyl-esterification (DM) were studied during somatic embryogenesis of banana (Musa spp. AAA). Histological analysis documented all major developmental stages including embryogenic cells (ECs), pre-globular, globular, pear-shaped and cotyledonary somatic embryos. Histochemical staining of extracellularly secreted pectins with ruthenium red showed the most intense staining at the surface of pre-globular, globular and pear-shaped somatic embryos. Biochemical analysis revealed developmental regulation of galacturonic acid content and DM in diverse embryogenic stages. Immunodots and immunolabeling on tissue sections revealed developmental regulation of highly methyl-esterified HG epitopes recognized by JIM7 and LM20 antibodies during somatic embryogenesis. Cell walls of pre-globular/globular and late-stage embryos contained both low methyl-esterified HG epitopes as well as partially and highly methyl-esterified ones. Extracellular matrix which covered surface of early developing embryos contained pectin epitopes recognized by 2F4, LM18, JIM5, JIM7 and LM5 antibodies. De-esterification of cell wall pectins by NaOH caused a decrease or an elimination of immunolabeling in the case of highly methyl-esterified HG epitopes. However, immunolabeling of some low methyl-esterified epitopes appeared stronger after this base treatment. Conclusions/Significance These data suggest that both low

IgE and allergen-specific immunotherapy-induced IgG4 recognize similar epitopes of Bet v 1, the major allergen of birch pollen.

Science.gov (United States)

Groh, N; von Loetzen, C S; Subbarayal, B; Möbs, C; Vogel, L; Hoffmann, A; Fötisch, K; Koutsouridou, A; Randow, S; Völker, E; Seutter von Loetzen, A; Rösch, P; Vieths, S; Pfützner, W; Bohle, B; Schiller, D

2017-05-01

Allergen-specific immunotherapy (AIT) with birch pollen generates Bet v 1-specific immunoglobulin (Ig)G 4 which blocks IgE-mediated hypersensitivity mechanisms. Whether IgG 4 specific for Bet v 1a competes with IgE for identical epitopes or whether novel epitope specificities of IgG 4 antibodies are developed is under debate. We sought to analyze the epitope specificities of IgE and IgG 4 antibodies from sera of patients who received AIT. 15 sera of patients (13/15 received AIT) with Bet v 1a-specific IgE and IgG 4 were analyzed. The structural arrangements of recombinant (r)Bet v 1a and rBet v 1a _11x , modified in five potential epitopes, were analyzed by circular dichroism and nuclear magnetic resonance spectroscopy. IgE binding to Bet v 1 was assessed by ELISA and mediator release assays. Competitive binding of monoclonal antibodies specific for Bet v 1a and serum IgE/IgG 4 to rBet v 1a and serum antibody binding to a non-allergenic Bet v 1-type model protein presenting an individual epitope for IgE was analyzed in ELISA and western blot. rBet v 1a _11x had a Bet v 1a - similar secondary and tertiary structure. Monomeric dispersion of rBet v 1a _11x was concentration and buffer-dependent. Up to 1500-fold increase in the EC 50 for IgE-mediated mediator release induced by rBet v 1a _11x was determined. The reduction of IgE and IgG 4 binding to rBet v 1a _11x was comparable in 67% (10/15) of sera. Bet v 1a-specific monoclonal antibodies inhibited binding of serum IgE and IgG 4 to 66.1% and 64.9%, respectively. Serum IgE and IgG 4 bound specifically to an individual epitope presented by our model protein in 33% (5/15) of sera. Patients receiving AIT develop Bet v 1a-specific IgG 4 which competes with IgE for partly identical or largely overlapping epitopes. The similarities of epitopes for IgE and IgG 4 might stimulate the development of epitope-specific diagnostics and therapeutics. © 2016 John Wiley & Sons Ltd.

A novel polyclonal antibody against human cytomegalovirus ...

African Journals Online (AJOL)

Future research should be directed to epitope screening of synthetic HMCV peptides, which could help to understand HCMV infection and virus-neutralising antibodies more fully and to prepare HCMV vaccines and antiviral drugs. Key words: Human cytomegalovirus, AD169 strain, Towne strains, polyclonal antibody.

Identification and characterization of a virus-specific continuous B-cell epitope on the PrM/M protein of Japanese Encephalitis Virus: potential application in the detection of antibodies to distinguish Japanese Encephalitis Virus infection from West Nile Virus and Dengue Virus infections

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Liu Wen-Xin

2010-09-01

Full Text Available Abstract Background Differential diagnose of Japanese encephalitis virus (JEV infection from other flavivirus especially West Nile virus (WNV and Dengue virus (DV infection was greatly hindered for the serological cross-reactive. Virus specific epitopes could benefit for developing JEV specific antibodies detection methods. To identify the JEV specific epitopes, we fully mapped and characterized the continuous B-cell epitope of the PrM/M protein of JEV. Results To map the epitopes on the PrM/M protein, we designed a set of 20 partially overlapping fragments spanning the whole PrM, fused them with GST, and expressed them in an expression vector. Linear epitope M14 (105VNKKEAWLDSTKATRY120 was detected by enzyme-linked immunosorbent assay (ELISA. By removing amino acid residues individually from the carboxy and amino terminal of peptide M14, we confirmed that the minimal unit of the linear epitope of PrM/M was M14-13 (108KEAWLDSTKAT118. This epitope was highly conserved across different JEV strains. Moreover, this epitope did not cross-react with WNV-positive and DENV-positive sera. Conclusion Epitope M14-13 was a JEV specific lineal B-cell epitpe. The results may provide a useful basis for the development of epitope-based virus specific diagnostic clinical techniques.

Identification of anti-CD98 antibody mimotopes for inducing antibodies with antitumor activity by mimotope immunization.

Science.gov (United States)

Saito, Misa; Kondo, Masahiro; Ohshima, Motohiro; Deguchi, Kazuki; Hayashi, Hideki; Inoue, Kazuyuki; Tsuji, Daiki; Masuko, Takashi; Itoh, Kunihiko

2014-04-01

A mimotope is an antibody-epitope-mimicking peptide retrieved from a phage display random peptide library. Immunization with antitumor antibody-derived mimotopes is promising for inducing antitumor immunity in hosts. In this study, we isolated linear and constrained mimotopes from HBJ127, a tumor-suppressing anti-CD98 heavy chain mAb, and determined their abilities for induction of antitumor activity equal to that of the parent antibody. We detected elevated levels of antipeptide responses, but failed to detect reactivity against native CD98-expressing HeLa cells in sera of immunized mice. Phage display panning and selection of mimotope-immunized mouse spleen-derived antibody Fab library showed that HeLa cell-reactive Fabs were successfully retrieved from the library. This finding indicates that native antigen-reactive Fab clones represented an undetectable minor population in mimotope-induced antibody repertoire. Functional and structural analysis of retrieved Fab clones revealed that they were almost identical to the parent antibody. From these results, we confirmed that mimotope immunization was promising for retrieving antitumor antibodies equivalent to the parent antibody, although the co-administration of adjuvant compounds such as T-cell epitope peptides and Toll-like receptor 4 agonist peptides is likely to be necessary for inducing stronger antitumor immunity than mimotope injection alone. © 2014 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association.

A novel HPV 16 L1-based chimeric virus-like particle containing E6 and E7 seroreactive epitopes permits highly specific detection of antibodies in patients with CIN 1 and HPV-16 infection

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Santiago-Osorio Edelmiro

2011-02-01

Full Text Available Abstract Background The presence of IgG antibodies to HPV-16 L1-virus like particles (VLPs in serum has been reported as a result of persistent exposure to the virus and as a marker of disease progression. However, detection of VLP-specific antibodies in sera does not always indicate a malignant lesion as positive results may also be due to a nonmalignant viral infection. Furthermore, malignant lesions are associated with an increased antibody titer for E6 and E7 proteins. The aim of this study was to develop an ELISA using a novel chimeric virus-like particle (cVLP encoding an L1 protein fused with a string of HPV-16 E6 and E7 seroreactive epitopes to its C-terminus to be used for detection of HPV-16 specific antibodies in patients with cervical intraepithelial lesion grade 1 (CIN 1. Results The sera of 30 patients with CIN 1 who also tested positive for HPV-16 DNA and of 30 age-matched normal donors negative for HPV infection were tested for the presence of IgG antibodies specific for either VLP-L1 (HPV-16 L1, gVLP (derived from Gardasil, or cVLP by ELISA. The cVLP-reactive sera yielded two distinct groups of results: (H reactivity levels that presented very strong cVLP-specific titers, and (L reactivity levels with significantly lower titers similar to those obtained with VLP-L1 and gVLP antigens. Additionally, the sera that presented the higher cVLP titers closely matched those that had significantly stronger reactivity to E6 and E7 epitopes. Interestingly, the samples with the highest titers corresponded to patients with the higher numbers of sexual partners and pregnancies. On the other hand only 4 out of the 12 sera that harbored antibodies with VLP neutralizing ability corresponded to the group with high cVLP antibody titers. Conclusion We report for the first time that chimeric particles containing HPV-16 L1 protein fused with E6 and E7 seroreactive epitopes enable much better detection of IgG antibodies in the sera of CIN 1 patients

Humoral immune responses of dengue fever patients using epitope-specific serotype-2 virus-like particle antigens.

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Wayne D Crill

Full Text Available Dengue virus (DENV is a serious mosquito-borne pathogen causing significant global disease burden, either as classic dengue fever (DF or in its most severe manifestation dengue hemorrhagic fever (DHF. Nearly half of the world's population is at risk of dengue disease and there are estimated to be millions of infections annually; a situation which will continue to worsen with increasing expansion of the mosquito vectors and epidemic DF/DHF. Currently there are no available licensed vaccines or antivirals for dengue, although significant effort has been directed toward the development of safe and efficacious dengue vaccines for over 30 years. Promising vaccine candidates are in development and testing phases, but a better understanding of immune responses to DENV infection and vaccination is needed. Humoral immune responses to DENV infection are complex and may exacerbate pathogenicity, yet are essential for immune protection. In this report, we develop DENV-2 envelope (E protein epitope-specific antigens and measure immunoglobulin responses to three distinct epitopes in DENV-2 infected human serum samples. Immunoglobulin responses to DENV-2 infection exhibited significant levels of individual variation. Antibody populations targeting broadly cross-reactive epitopes centered on the fusion peptide in structural domain II were large, highly variable, and greater in primary than in secondary DENV-2 infected sera. E protein domain III cross-reactive immunoglobulin populations were similarly variable and much larger in IgM than in IgG. DENV-2 specific domain III IgG formed a very small proportion of the antibody response yet was significantly correlated with DENV-2 neutralization, suggesting that the highly protective IgG recognizing this epitope in murine studies plays a role in humans as well. This report begins to tease apart complex humoral immune responses to DENV infection and is thus important for improving our understanding of dengue disease

Maximizing in vivo target clearance by design of pH-dependent target binding antibodies with altered affinity to FcRn.

Science.gov (United States)

Yang, Danlin; Giragossian, Craig; Castellano, Steven; Lasaro, Marcio; Xiao, Haiguang; Saraf, Himanshu; Hess Kenny, Cynthia; Rybina, Irina; Huang, Zhong-Fu; Ahlberg, Jennifer; Bigwarfe, Tammy; Myzithras, Maria; Waltz, Erica; Roberts, Simon; Kroe-Barrett, Rachel; Singh, Sanjaya

2017-10-01

Antibodies with pH-dependent binding to both target antigens and neonatal Fc receptor (FcRn) provide an alternative tool to conventional neutralizing antibodies, particularly for therapies where reduction in antigen level is challenging due to high target burden. However, the requirements for optimal binding kinetic framework and extent of pH dependence for these antibodies to maximize target clearance from circulation are not well understood. We have identified a series of naturally-occurring high affinity antibodies with pH-dependent target binding properties. By in vivo studies in cynomolgus monkeys, we show that pH-dependent binding to the target alone is not sufficient for effective target removal from circulation, but requires Fc mutations that increase antibody binding to FcRn. Affinity-enhanced pH-dependent FcRn binding that is double-digit nM at pH 7.4 and single-digit nM at pH 6 achieved maximal target reduction when combined with similar target binding affinities in reverse pH directions. Sustained target clearance below the baseline level was achieved 3 weeks after single-dose administration at 1.5 mg/kg. Using the experimentally derived mechanistic model, we demonstrate the essential kinetic interplay between target turnover and antibody pH-dependent binding during the FcRn recycling, and identify the key components for achieving maximal target clearance. These results bridge the demand for improved patient dosing convenience with the "know-how" of therapeutic modality by design.

Clinical and Immunological Features of Opsoclonus-Myoclonus Syndrome in the Era of Neuronal Cell Surface Antibodies.

Science.gov (United States)

Armangué, Thaís; Sabater, Lidia; Torres-Vega, Estefanía; Martínez-Hernández, Eugenia; Ariño, Helena; Petit-Pedrol, Mar; Planagumà, Jesús; Bataller, Luis; Dalmau, Josep; Graus, Francesc

2016-04-01

Most studies on opsoclonus-myoclonus syndrome (OMS) in adults are based on small case series before the era of neuronal cell surface antibody discovery. To report the clinical and immunological features of idiopathic OMS (I-OMS) and paraneoplastic OMS (P-OMS), the occurrence of antibodies to cell surface antigens, and the discovery of a novel cell surface epitope. Retrospective cohort study and laboratory investigations of 114 adult patients with OMS at a center for autoimmune neurological disorders done between January 2013 and September 2015. Review of clinical records. Immunohistochemistry on rat brain and cultured neurons as well as cell-based assays were used to identify known autoantibodies. Immunoprecipitation and mass spectrometry were used to characterize novel antigens. Of the 114 patients (62 [54%] female; median age, 45 years; interquartile range, 32-60 years), 45 (39%) had P-OMS and 69 (61%) had I-OMS. In patients with P-OMS, the associated tumors included lung cancer (n = 19), breast cancer (n = 10), other cancers (n = 5), and ovarian teratoma (n = 8); 3 additional patients without detectable cancer were considered to have P-OMS because they had positive results for onconeuronal antibodies. Patients with I-OMS, compared with those who had P-OMS, were younger (median age, 38 [interquartile range, 31-50] vs 54 [interquartile range, 45-65] years; P OMS with lung cancer (21% vs 5% in patients with OMS without lung cancer; P = .02); however, a similar frequency of glycine receptor antibodies was found in patients with lung cancer without OMS (13 of 65 patients [20%]). A novel cell surface epitope, human natural killer 1 (HNK-1), was the target of the antibodies in 3 patients with lung cancer and P-OMS. Patients with I-OMS responded better to treatment and had fewer relapses than those with P-OMS. Older age and encephalopathy, significantly associated with P-OMS, are clinical clues suggesting an underlying tumor. Glycine receptor antibodies occur

Fluorometric titration approach for calibration of quantity of binding site of purified monoclonal antibody recognizing epitope/hapten nonfluorescent at 340 nm.

Science.gov (United States)

Yang, Xiaolan; Hu, Xiaolei; Xu, Bangtian; Wang, Xin; Qin, Jialin; He, Chenxiong; Xie, Yanling; Li, Yuanli; Liu, Lin; Liao, Fei

2014-06-17

A fluorometric titration approach was proposed for the calibration of the quantity of monoclonal antibody (mcAb) via the quench of fluorescence of tryptophan residues. It applied to purified mcAbs recognizing tryptophan-deficient epitopes, haptens nonfluorescent at 340 nm under the excitation at 280 nm, or fluorescent haptens bearing excitation valleys nearby 280 nm and excitation peaks nearby 340 nm to serve as Förster-resonance-energy-transfer (FRET) acceptors of tryptophan. Titration probes were epitopes/haptens themselves or conjugates of nonfluorescent haptens or tryptophan-deficient epitopes with FRET acceptors of tryptophan. Under the excitation at 280 nm, titration curves were recorded as fluorescence specific for the FRET acceptors or for mcAbs at 340 nm. To quantify the binding site of a mcAb, a universal model considering both static and dynamic quench by either type of probes was proposed for fitting to the titration curve. This was easy for fitting to fluorescence specific for the FRET acceptors but encountered nonconvergence for fitting to fluorescence of mcAbs at 340 nm. As a solution, (a) the maximum of the absolute values of first-order derivatives of a titration curve as fluorescence at 340 nm was estimated from the best-fit model for a probe level of zero, and (b) molar quantity of the binding site of the mcAb was estimated via consecutive fitting to the same titration curve by utilizing such a maximum as an approximate of the slope for linear response of fluorescence at 340 nm to quantities of the mcAb. This fluorometric titration approach was proved effective with one mcAb for six-histidine and another for penicillin G.

Expression and purification of chimeric peptide comprising EGFR B-cell epitope and measles virus fusion protein T-cell epitope in Escherichia coli.

Science.gov (United States)

Wu, Meizhi; Zhao, Lin; Zhu, Lei; Chen, Zhange; Li, Huangjin

2013-03-01

Chimeric peptide MVF-EGFR(237-267), comprising a B-cell epitope from the dimerization interface of human epidermal growth factor receptor (EGFR) and a promiscuous T-cell epitope from measles virus fusion protein (MVF), is a promising candidate antigen peptide for therapeutic vaccine. To establish a high-efficiency preparation process of this small peptide, the coding sequence was cloned into pET-21b and pET-32a respectively, to be expressed alone or in the form of fusion protein with thioredoxin (Trx) and His(6)-tag in Escherichia coli BL21 (DE3). The chimeric peptide failed to be expressed alone, but over-expressed in the fusion form, which presented as soluble protein and took up more than 30% of total proteins of host cells. The fusion protein was seriously degraded during the cell disruption, in which endogenous metalloproteinase played a key role. Degradation of target peptide was inhibited by combined application of EDTA in the cell disruption buffer and a step of Source 30Q anion exchange chromatography (AEC) before metal-chelating chromatography (MCAC) for purifying His(6)-tagged fusion protein. The chimeric peptide was recovered from the purified fusion protein by enterokinase digestion at a yield of 3.0 mg/L bacteria culture with a purity of more than 95%. Immunogenicity analysis showed that the recombinant chimeric peptide was able to arouse more than 1×10(4) titers of specific antibody in BALB/c mice. Present work laid a solid foundation for the development of therapeutic peptide vaccine targeting EGFR dimerization and provided a convenient and low-cost preparation method for small peptides. Copyright © 2012 Elsevier Inc. All rights reserved.

[Antibody therapy for Alzheimer's disease].

Science.gov (United States)

Tabira, Takeshi; Matsumoto, Shin-Ei; Jin, Haifeng

2011-11-01

In order to avoid Abeta-induced autoimmune encephalitis, several monoclonal and polyclonal antibodies are in clinical trials. These are bapineuzumab, solanezumab, ponezumab, gantenerumab, BAN2401, gammaguard and octagam. Since each antibody has a different antigen epitope of Abeta, anti-amyloid activities are different. It is unknown which antibody is effective for Alzheimer disease, and we must wait for the result of clinical trials. Some patients who developed tissue amyloid plaque immuno-reactive (TAPIR) antibody showed slower decline after AN-1792 vaccination. We developed TAPIR-like monoclonal antibody, which was found to react with Abeta oligomers preferentially.

[Chemical modification of allergen leading to changes in its epitopic activity].

Science.gov (United States)

Babakhin, A A; Gushchin, I S; Andreev, S M; Petrukhina, A I; Viler, A V; Stokinger, B; Nolte, G; Dubuske, L M; Khaitov, R M; Petrpv, R V

1999-01-01

Modification of a model allergen ovalbumin (OA) with succinylation led to a decrease of its allergenicity measured by passive cutaneous anaphylaxis reaction, RAST inhibition assay and basophil histamine release. Modified OA stimulated OA-specific T-cell hybrid 3DO-548 to produce IL-2 at the same level as in case of non-modified OA. Modified OA did not induce anti-OA IgE, but did induce anti-OA IgG antibodies. This approach to chemical modification of allergen-selective blockade of B-cell epitopes while not affecting T-cell epitopes suggests new opportunities in creation of safe and effective allergovaccines.

Mapping of epitopes for autoantibodies to the Type 1 diabetes autoantigen IA-2 by peptide phage display and molecular modelling: Overlap of antibody and T-cell determinants

DEFF Research Database (Denmark)

A. Dromey, James; Weenink, Sarah M.; Peters, Günther H.J.

2004-01-01

IA-2 is a major target of autoimmunity in type 1 diabetes. IA-2 responsive T cells recognize determinants within regions represented by amino acids 787–817 and 841–869 of the molecule. Epitopes for IA-2 autoantibodies are largely conformational and not well defined. In this study, we used peptide......, and aromatic residues and amino acids contributing to the epitope investigated using site-directed mutagenesis. Mutation of each of amino acids Asn858, Glu836, and Trp799 reduced 96/3 Ab binding by >45%. Mutations of these residues also inhibited binding of serum autoantibodies from IA-2 Ab-positive type 1...... phage display and homology modeling to characterize the epitope of a monoclonal IA-2 Ab (96/3) from a human type 1 diabetic patient. This Ab competes for IA-2 binding with Abs from the majority of patients with type 1 diabetes and therefore binds a region close to common autoantibody epitopes. Alignment...

Recognition of Porphyromonas gingivalis gingipain epitopes by natural IgM binding to malondialdehyde modified low-density lipoprotein.

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S Pauliina Turunen

Full Text Available OBJECTIVE: Increased risk for atherosclerosis is associated with infectious diseases including periodontitis. Natural IgM antibodies recognize pathogen-associated molecular patterns on bacteria, and oxidized lipid and protein epitopes on low-density lipoprotein (LDL and apoptotic cells. We aimed to identify epitopes on periodontal pathogen Porphyromonas gingivalis recognized by natural IgM binding to malondialdehyde (MDA modified LDL. METHODS AND RESULTS: Mouse monoclonal IgM (MDmAb specific for MDA-LDL recognized epitopes on P. gingivalis on flow cytometry and chemiluminescence immunoassays. Immunization of C57BL/6 mice with P. gingivalis induced IgM, but not IgG, immune response to MDA-LDL and apoptotic cells. Immunization of LDLR(-/- mice with P. gingivalis induced IgM, but not IgG, immune response to MDA-LDL and diminished aortic lipid deposition. On Western blot MDmAb bound to P. gingivalis fragments identified as arginine-specific gingipain (Rgp by mass spectrometry. Recombinant domains of Rgp produced in E. coli were devoid of phosphocholine epitopes but contained epitopes recognized by MDmAb and human serum IgM. Serum IgM levels to P. gingivalis were associated with anti-MDA-LDL levels in humans. CONCLUSION: Gingipain of P. gingivalis is recognized by natural IgM and shares molecular identity with epitopes on MDA-LDL. These findings suggest a role for natural antibodies in the pathogenesis of two related inflammatory diseases, atherosclerosis and periodontitis.

Multiple linear B-cell epitopes of classical swine fever virus glycoprotein E2 expressed in E.coli as multiple epitope vaccine induces a protective immune response

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Wei Jian-Chao

2011-07-01

Full Text Available Abstract Classical swine fever is a highly contagious disease of swine caused by classical swine fever virus, an OIE list A pathogen. Epitope-based vaccines is one of the current focuses in the development of new vaccines against classical swine fever virus (CSFV. Two B-cell linear epitopes rE2-ba from the E2 glycoprotein of CSFV, rE2-a (CFRREKPFPHRMDCVTTTVENED, aa844-865 and rE2-b (CKEDYRYAISSTNEIGLLGAGGLT, aa693-716, were constructed and heterologously expressed in Escherichia coli as multiple epitope vaccine. Fifteen 6-week-old specified-pathogen-free (SPF piglets were intramuscularly immunized with epitopes twice at 2-week intervals. All epitope-vaccinated pigs could mount an anamnestic response after booster vaccination with neutralizing antibody titers ranging from 1:16 to 1:256. At this time, the pigs were subjected to challenge infection with a dose of 1 × 106 TCID50 virulent CSFV strain. After challenge infection, all of the rE2-ba-immunized pigs were alive and without symptoms or signs of CSF. In contrast, the control pigs continuously exhibited signs of CSF and had to be euthanized because of severe clinical symptoms at 5 days post challenge infection. The data from in vivo experiments shown that the multiple epitope rE2-ba shown a greater protection (similar to that of HCLV vaccine than that of mono-epitope peptide(rE2-a or rE2-b. Therefore, The results demonstrated that this multiple epitope peptide expressed in a prokaryotic system can be used as a potential DIVA (differentiating infected from vaccinated animals vaccine. The E.coli-expressed E2 multiple B-cell linear epitopes retains correct immunogenicity and is able to induce a protective immune response against CSFV infection.

Synthetic Long Peptide Influenza Vaccine Containing Conserved T and B Cell Epitopes Reduces Viral Load in Lungs of Mice and Ferrets.

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S K Rosendahl Huber

Full Text Available Currently licensed influenza vaccines mainly induce antibodies against highly variable epitopes. Due to antigenic drift, protection is subtype or strain-specific and regular vaccine updates are required. In case of antigenic shifts, which have caused several pandemics in the past, completely new vaccines need to be developed. We set out to develop a vaccine that provides protection against a broad range of influenza viruses. Therefore, highly conserved parts of the influenza A virus (IAV were selected of which we constructed antibody and T cell inducing peptide-based vaccines. The B epitope vaccine consists of the highly conserved HA2 fusion peptide and M2e peptide coupled to a CD4 helper epitope. The T epitope vaccine comprises 25 overlapping synthetic long peptides of 26-34 amino acids, thereby avoiding restriction for a certain MHC haplotype. These peptides are derived from nucleoprotein (NP, polymerase basic protein 1 (PB1 and matrix protein 1 (M1. C57BL/6 mice, BALB/c mice, and ferrets were vaccinated with the B epitopes, 25 SLP or a combination of both. Vaccine-specific antibodies were detected in sera of mice and ferrets and vaccine-specific cellular responses were measured in mice. Following challenge, both mice and ferrets showed a reduction of virus titers in the lungs in response to vaccination. Summarizing, a peptide-based vaccine directed against conserved parts of influenza virus containing B and T cell epitopes shows promising results for further development. Such a vaccine may reduce disease burden and virus transmission during pandemic outbreaks.

Structural and Antigenic Definition of Hepatitis C Virus E2 Glycoprotein Epitopes Targeted by Monoclonal Antibodies

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Giuseppe Sautto

2013-01-01

Full Text Available Hepatitis C virus (HCV is the major cause of chronic liver disease as well as the major indication for liver transplantation worldwide. Current standard of care is not completely effective, not administrable in grafted patients, and burdened by several side effects. This incomplete effectiveness is mainly due to the high propensity of the virus to continually mutate under the selective pressure exerted by the host immune response as well as currently administered antiviral drugs. The E2 envelope surface glycoprotein of HCV (HCV/E2 is the main target of the host humoral immune response and for this reason one of the major variable viral proteins. However, broadly cross-neutralizing monoclonal antibodies (mAbs directed against HCV/E2 represent a promising tool for the study of virus-host interplay as well as for the development of effective prophylactic and therapeutic approaches. In the last few years many anti-HCV/E2 mAbs have been evaluated in preclinical and clinical trials as possible candidate antivirals, particularly for administration in pre- and post-transplant settings. In this review we summarize the antigenic and structural characteristics of HCV/E2 determined through the use of anti-HCV/E2 mAbs, which, given the absence of a crystal structure of this glycoprotein, represent currently the best tool available.

Dengue virus specific IgY provides protection following lethal dengue virus challenge and is neutralizing in the absence of inducing antibody dependent enhancement.

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Fink, Ashley L; Williams, Katherine L; Harris, Eva; Alvine, Travis D; Henderson, Thomas; Schiltz, James; Nilles, Matthew L; Bradley, David S

2017-07-01

Dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) are severe disease manifestations that can occur following sequential infection with different dengue virus serotypes (DENV1-4). At present, there are no licensed therapies to treat DENV-induced disease. DHF and DSS are thought to be mediated by serotype cross-reactive antibodies that facilitate antibody-dependent enhancement (ADE) by binding to viral antigens and then Fcγ receptors (FcγR) on target myeloid cells. Using genetically engineered DENV-specific antibodies, it has been shown that the interaction between the Fc portion of serotype cross-reactive antibodies and FcγR is required to induce ADE. Additionally, it was demonstrated that these antibodies were as neutralizing as their non-modified variants, were incapable of inducing ADE, and were therapeutic following a lethal, antibody-enhanced infection. Therefore, we hypothesized that avian IgY, which do not interact with mammalian FcγR, would provide a novel therapy for DENV-induced disease. We demonstrate here that goose-derived anti-DENV2 IgY neutralized DENV2 and did not induce ADE in vitro. Anti-DENV2 IgY was also protective in vivo when administered 24 hours following a lethal DENV2 infection. We were also able to demonstrate via epitope mapping that both full-length and alternatively spliced anti-DENV2 IgY recognized different epitopes, including epitopes that have not been previously identified. These observations provide evidence for the potential therapeutic applications of goose-derived anti-DENV2 IgY.

Dengue virus specific IgY provides protection following lethal dengue virus challenge and is neutralizing in the absence of inducing antibody dependent enhancement.

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Ashley L Fink

2017-07-01

Full Text Available Dengue hemorrhagic fever (DHF and dengue shock syndrome (DSS are severe disease manifestations that can occur following sequential infection with different dengue virus serotypes (DENV1-4. At present, there are no licensed therapies to treat DENV-induced disease. DHF and DSS are thought to be mediated by serotype cross-reactive antibodies that facilitate antibody-dependent enhancement (ADE by binding to viral antigens and then Fcγ receptors (FcγR on target myeloid cells. Using genetically engineered DENV-specific antibodies, it has been shown that the interaction between the Fc portion of serotype cross-reactive antibodies and FcγR is required to induce ADE. Additionally, it was demonstrated that these antibodies were as neutralizing as their non-modified variants, were incapable of inducing ADE, and were therapeutic following a lethal, antibody-enhanced infection. Therefore, we hypothesized that avian IgY, which do not interact with mammalian FcγR, would provide a novel therapy for DENV-induced disease. We demonstrate here that goose-derived anti-DENV2 IgY neutralized DENV2 and did not induce ADE in vitro. Anti-DENV2 IgY was also protective in vivo when administered 24 hours following a lethal DENV2 infection. We were also able to demonstrate via epitope mapping that both full-length and alternatively spliced anti-DENV2 IgY recognized different epitopes, including epitopes that have not been previously identified. These observations provide evidence for the potential therapeutic applications of goose-derived anti-DENV2 IgY.

A single simple procedure for dewaxing, hydration and heat-induced epitope retrieval (HIER for immunohistochemistry in formalin fixed paraffin-embedded tissue

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I.M.S. Paulsen

2015-11-01

Full Text Available Heat-induced epitope retrieval (HIER is widely used for immunohistochemistry on formalin fixed paraffin-embedded tissue and includes temperatures well above the melting point of paraffin. We therefore tested whether traditional xylene-based removal of paraffin is required on sections from paraffin-embedded tissue, when HIER is performed by vigorous boiling in 10 mM Tris/0.5 mM EGTA-buffer (pH=9. Immunohistochemical results using HIER with or without prior dewaxing in xylene were evaluated using 7 primary antibodies targeting proteins located in the cytosol, intracellular vesicles and plasma membrane. No effect of omitting prior dewaxing was observed on staining pattern. Semiquantitative analysis did not show HIER to influence the intensity of labelling consistently. Consequently, quantification of immune labelling intensity using fluorescent secondary antibodies was performed at 5 dilutions of primary antibody with and without prior dewaxing in xylene. No effect of omitting prior dewaxing on signal intensity was detectable indicating similar immunoreactivity in dewaxed and non-dewaxed sections. The intensity of staining the nucleus with the DNA-stain ToPro3 was similarly unaffected by omission of dewaxing in xylene. In conclusion, the HIER procedure described and tested can be used as a single procedure enabling dewaxing, hydration and epitope retrieval for immunohistochemistry in formalin fixed paraffin-embedded tissue.

Development of Monoclonal Antibodies Recognizing Linear Epitope: Illustration by Three Bacillus thuringiensis Crystal Proteins of Genetically Modified Cotton, Maize, and Tobacco.

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Cao, Zhen; Zhang, Wei; Ning, Xiangxue; Wang, Baomin; Liu, Yunjun; Li, Qing X

2017-11-22

Bacillus thuringiensis Cry1Ac, Cry1Ia1, and Cry1Ie are δ-endotoxin insecticidal proteins widely implemented in genetically modified organisms (GMO), such as cotton, maize, and potato. Western blot assay integrates electrophoresis separation power and antibody high specificity for monitoring specific exogenous proteins expressed in GMO. Procedures for evoking monoclonal antibody (mAb) for Western blot were poorly documented. In the present study, Cry1Ac partially denatured at 100 °C for 5 min was used as an immunogen to develop mAbs selectively recognizing a linear epitope of Cry1Ac for Western blot. mAb 5E9C6 and 3E6E2 selected with sandwich ELISA strongly recognized the heat semidenatured Cry1Ac. Particularly, 3E6E2 recognized both E. coli and cotton seed expressed Cry1Ac in Western blot. Such strategy of using partially denatured proteins as immunogens and using sandwich ELISA for mAb screening was also successfully demonstrated with production of mAbs against Cry1Ie for Western blot assay in maize.

Design, construction and evaluation of multi-epitope antigens for diagnosis of Lyme disease.

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Schreterova, Eva; Bhide, Mangesh; Potocnakova, Lenka; Borszekova Pulzova, Lucia

2017-12-23

Introduction and objective. Lyme disease (LD) is the most common vector-borne disease in the temperate zone of the Northern Hemisphere. Diagnosis of LD is mainly based on clinical symptoms supported with serology (detection of anti-Borrelia antibodies) and is often misdiagnosed in areas of endemicity. In this study, the chimeric proteins (A/C-2, A/C-4 and A/C-7.1) consisting of B-cell epitopes of outer surface proteins OspA and OspC from Borrelia genospecies prevalent in Eastern Slovakia, were designed, over-expressed in E. coli, and used to detect specific anti-Borrelia antibodies in serologically characterized sera from patients with Lyme-like symptoms to evaluate their diagnostic potential. Results showed that chimeras vary in their immuno-reactivity when tested with human sera. Compared with the results obtained from a two-tier test, the application of recombinant multi-epitope chimeric proteins as diagnosis antigens, produced fair agreement in the case of A/C-2 (0.20<κ<0.40) and good agreement (0.60<κ<0.80) when A/C-7.1 was used as capture antigen. Chimera A/C-4 were excluded from further study due to loss of reactivity with OspA-specific antibodies. The combination of specific B-cell epitopes from OspA and OspC proteins may improve the diagnostic accuracy of serologic assays, but further studies are required to address this hypothesis.

Dynamics behind affinity maturation of an anti-HCMV antibody family influencing antigen binding

KAUST Repository

Di Palma, Francesco; Tramontano, Anna

2017-01-01

The investigation of antibody affinity maturation and its effects on antigen binding is important with respect to understanding the regulation of the immune response. To shed light on this crucial process, we analyzed two Igs neutralizing the human cytomegalovirus: the primary germline antibody M2J1 and its related mature antibody 8F9. Both antibodies target the AD-2S1 epitope of the gB envelope protein and are considered to establish similar interactions with the cognate antigen. We used molecular dynamics simulations to understand the effect of mutations on the antibody–antigen interactions. The results provide a qualitative explanation for the increased 8F9 peptide affinity compared with that of M2J1. The emerging atomistic-detailed description of these complexes reveals the molecular effects of the somatic hypermutations occurring during affinity maturation.

Dynamics behind affinity maturation of an anti-HCMV antibody family influencing antigen binding

KAUST Repository

Di Palma, Francesco

2017-08-03

The investigation of antibody affinity maturation and its effects on antigen binding is important with respect to understanding the regulation of the immune response. To shed light on this crucial process, we analyzed two Igs neutralizing the human cytomegalovirus: the primary germline antibody M2J1 and its related mature antibody 8F9. Both antibodies target the AD-2S1 epitope of the gB envelope protein and are considered to establish similar interactions with the cognate antigen. We used molecular dynamics simulations to understand the effect of mutations on the antibody–antigen interactions. The results provide a qualitative explanation for the increased 8F9 peptide affinity compared with that of M2J1. The emerging atomistic-detailed description of these complexes reveals the molecular effects of the somatic hypermutations occurring during affinity maturation.

Development of a Blocking ELISA Using a Monoclonal Antibody to a Dominant Epitope in Non-Structural Protein 3A of Foot-and-Mouth Disease Virus, as a Matching Test for a Negative-Marker Vaccine.

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Yuanfang Fu

Full Text Available Foot-and-mouth disease (FMD is a devastating animal disease. Strategies for differentiation of infected from vaccinated animals (DIVA remain very important for controlling disease. Development of an epitope-deleted marker vaccine and accompanying diagnostic method will improve the efficiency of DIVA. Here, a monoclonal antibody (Mab was found to recognize a conserved "AEKNPLE" epitope spanning amino acids 109-115 of non-structural protein (NSP 3A of foot-and-mouth disease virus (FMDV; O/Tibet/CHA/99 strain, which could be deleted by a reverse-genetic procedure. In addition, a blocking ELISA was developed based on this Mab against NSP 3A, which could serve as a matching test for a negative-marker vaccine. The criterion of this blocking ELISA was determined by detecting panels of sera from different origins. The serum samples with a percentage inhibition (PI equal or greater than 50% were considered to be from infected animals, and those with <50% PI were considered to be from non-infected animals. This test showed similar performance when compared with other 2 blocking ELISAs based on an anti-NSP 3B Mab. This is the first report of the DIVA test for an NSP antibody based on an Mab against the conserved and predominant "AEKNPLE" epitope in NSP 3A of FMDV.

Antibody-Induced Internalization of the Human Respiratory Syncytial Virus Fusion Protein.

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Leemans, A; De Schryver, M; Van der Gucht, W; Heykers, A; Pintelon, I; Hotard, A L; Moore, M L; Melero, J A; McLellan, J S; Graham, B S; Broadbent, L; Power, U F; Caljon, G; Cos, P; Maes, L; Delputte, P

2017-07-15

Respiratory syncytial virus (RSV) infections remain a major cause of respiratory disease and hospitalizations among infants. Infection recurs frequently and establishes a weak and short-lived immunity. To date, RSV immunoprophylaxis and vaccine research is mainly focused on the RSV fusion (F) protein, but a vaccine remains elusive. The RSV F protein is a highly conserved surface glycoprotein and is the main target of neutralizing antibodies induced by natural infection. Here, we analyzed an internalization process of antigen-antibody complexes after binding of RSV-specific antibodies to RSV antigens expressed on the surface of infected cells. The RSV F protein and attachment (G) protein were found to be internalized in both infected and transfected cells after the addition of either RSV-specific polyclonal antibodies (PAbs) or RSV glycoprotein-specific monoclonal antibodies (MAbs), as determined by indirect immunofluorescence staining and flow-cytometric analysis. Internalization experiments with different cell lines, well-differentiated primary bronchial epithelial cells (WD-PBECs), and RSV isolates suggest that antibody internalization can be considered a general feature of RSV. More specifically for RSV F, the mechanism of internalization was shown to be clathrin dependent. All RSV F-targeted MAbs tested, regardless of their epitopes, induced internalization of RSV F. No differences could be observed between the different MAbs, indicating that RSV F internalization was epitope independent. Since this process can be either antiviral, by affecting virus assembly and production, or beneficial for the virus, by limiting the efficacy of antibodies and effector mechanism, further research is required to determine the extent to which this occurs in vivo and how this might impact RSV replication. IMPORTANCE Current research into the development of new immunoprophylaxis and vaccines is mainly focused on the RSV F protein since, among others, RSV F-specific antibodies are

Inhibition of EBV-mediated membrane fusion by anti-gHgL antibodies

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Sathiyamoorthy, Karthik; Jiang, Jiansen; Möhl, Britta S.; Chen, Jia; Zhou, Z. Hong; Longnecker, Richard; Jardetzky, Theodore S. (UCLA); (Stanford-MED); (NWU)

2017-09-22

Herpesvirus entry into cells requires the coordinated action of multiple virus envelope glycoproteins, including gH, gL, and gB. For EBV, the gp42 protein assembles into complexes with gHgL heterodimers and binds HLA class II to activate gB-mediated membrane fusion with B cells. EBV tropism is dictated by gp42 levels in the virion, as it inhibits entry into epithelial cells while promoting entry into B cells. The gHgL and gB proteins are targets of neutralizing antibodies and potential candidates for subunit vaccine development, but our understanding of their neutralizing epitopes and the mechanisms of inhibition remain relatively unexplored. Here we studied the structures and mechanisms of two anti-gHgL antibodies, CL40 and CL59, that block membrane fusion with both B cells and epithelial cells. We determined the structures of the CL40 and CL59 complexes with gHgL using X-ray crystallography and EM to identify their epitope locations. CL59 binds to the C-terminal domain IV of gH, while CL40 binds to a site occupied by the gp42 receptor binding domain. CL40 binding to gHgL/gp42 complexes is not blocked by gp42 and does not interfere with gp42 binding to HLA class II, indicating that its ability to block membrane fusion with B cells represents a defect in gB activation. These data indicate that anti-gHgL neutralizing antibodies can block gHgL-mediated activation of gB through different surface epitopes and mechanisms.

An assessment on epitope prediction methods for protozoa genomes

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Resende Daniela M

2012-11-01

Full Text Available Abstract Background Epitope prediction using computational methods represents one of the most promising approaches to vaccine development. Reduction of time, cost, and the availability of completely sequenced genomes are key points and highly motivating regarding the use of reverse vaccinology. Parasites of genus Leishmania are widely spread and they are the etiologic agents of leishmaniasis. Currently, there is no efficient vaccine against this pathogen and the drug treatment is highly toxic. The lack of sufficiently large datasets of experimentally validated parasites epitopes represents a serious limitation, especially for trypanomatids genomes. In this work we highlight the predictive performances of several algorithms that were evaluated through the development of a MySQL database built with the purpose of: a evaluating individual algorithms prediction performances and their combination for CD8+ T cell epitopes, B-cell epitopes and subcellular localization by means of AUC (Area Under Curve performance and a threshold dependent method that employs a confusion matrix; b integrating data from experimentally validated and in silico predicted epitopes; and c integrating the subcellular localization predictions and experimental data. NetCTL, NetMHC, BepiPred, BCPred12, and AAP12 algorithms were used for in silico epitope prediction and WoLF PSORT, Sigcleave and TargetP for in silico subcellular localization prediction against trypanosomatid genomes. Results A database-driven epitope prediction method was developed with built-in functions that were capable of: a removing experimental data redundancy; b parsing algorithms predictions and storage experimental validated and predict data; and c evaluating algorithm performances. Results show that a better performance is achieved when the combined prediction is considered. This is particularly true for B cell epitope predictors, where the combined prediction of AAP12 and BCPred12 reached an AUC value

Identification of two novel rabbit hemorrhagic disease virus (RHDV) B cell epitopes and evaluation of its immunoprotection against RHDV.

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DeSheng, Kong; HuaiRan, Liu; JiaSen, Liu; Zuo, Yu; Qian, Jiang; DongChun, Guo; XiaoLiang, Hu; FengJie, Wang; QianQian, Huang; LianDong, Qu

2015-07-01

The VP60 protein of rabbit hemorrhagic disease virus (RHDV) is a structural protein with important roles in viral replication and assembly. In this study, we immunized BALB/c mice with the RHDV-TP strain. Six monoclonal antibodies (mAbs) were selected and characterized by enzyme-linked immunosorbent assay, Western blotting, and indirectly immunofluorescence analysis (IFA). All six mAbs (AD4, AG10, BC9, BE8, BH3, and DE2) had positive reactions with recombinant VP60 as analyzed by IFA, but only two (AG10 and DE2) reacted with denatured RHDV by Western blotting. Fifty-four partially overlapping fragments of the VP60 gene were expressed with His or Glutathione S-transferase (GST) tags to identify the epitopes recognized by AG10 and DE2. These two epitopes were located at the C-terminal of VP60 and were longer (64 and 53 amino acids, respectively) than normal B cell epitopes. However, both AG10 and DE2 also interacted with RHDV2 VP60 expressed in insect cells. Amino acid alignments of the AG10 and DE2 epitope regions between RHDV and RHDV2 VP60 indicated several mutations, suggesting that the epitopes recognized by the mAbs AG10 and DE2 were discontinuous. Epitope immunogenicity was evaluated by inoculating specific pathogen-free rabbits with saline, purified DE2 epitope, or RHDV inactive vaccine. Rabbits immunized with the DE2 epitope developed high levels of RHDV-specific antibodies but no cellular immune response and died after challenge with RHDV-HYD isolate. Despite their lack of neutralizing activity, these mAb reagents and epitopes may have useful clinical applications and will be valuable tools in further studies of the structure and function of the RHDV VP60 protein.

Characterization of a monoclonal antibody with specificity for holo-transcobalamin

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Fedosov Sergey N

2006-01-01

Full Text Available Abstract Background Holotranscobalamin, cobalamin-saturated transcobalamin, is the minor fraction of circulating cobalamin (vitamin B12, which is available for cellular uptake and hence is physiologically relevant. Currently, no method allows simple, direct quantification of holotranscobalamin. We now report on the identification and characterization of a monoclonal antibody with a unique specificity for holotranscobalamin. Methods The specificity and affinity of the monoclonal antibodies were determined using surface plasmon resonance and recombinant transcobalamin as well as by immobilizing the antibodies on magnetic microspheres and using native transcobalamin in serum. The epitope of the holotranscobalamin specific antibody was identified using phage display and comparison to a de novo generated three-dimensional model of transcobalamin using the program Rosetta. A direct assay for holotrnscobalamin in the ELISA format was developed using the specific antibody and compared to the commercial assay HoloTC RIA. Results An antibody exhibiting >100-fold specificity for holotranscobalamin over apotranscobalamin was identified. The affinity but not the specificity varied inversely with ionic strength and pH, indicating importance of electrostatic interactions. The epitope was discontinuous and epitope mapping of the antibody by phage display identified two similar motifs with no direct sequence similarity to transcobalamin. A comparison of the motifs with a de novo generated three-dimensional model of transcobalamin identified two structures in the N-terminal part of transcobalamin that resembled the motif. Using this antibody an ELISA based prototype assay was developed and compared to the only available commercial assay for measuring holotranscobalamin, HoloTC RIA. Conclusion The identified antibody possesses a unique specificity for holotranscobalamin and can be used to develop a direct assay for the quantification of holotranscobalamin.

Specific recognition of the C-terminal end of A beta 42 by a high affinity monoclonal antibody

DEFF Research Database (Denmark)

Axelsen, Trine Veje; Holm, Arne; Birkelund, Svend

2009-01-01

The neurotoxic peptide A beta(42) is derived from the amyloid precursor protein by proteolytic cleavage and is deposited in the brain of patients suffering from Alzheimer's disease (AD). In this study we generate a high affinity monoclonal antibody that targets the C-terminal end of A beta(42......) with high specificity. By this is meant that the paratope of the antibody must enclose the C-terminal end of A beta(42) including the carboxy-group of amino acid 42, and not just recognize a linear epitope in the C-terminal part of A beta. This has been accomplished by using a unique antigen construct made...... by the Ligand Presenting Assembly technology (LPA technology). This strategy results in dimeric presentation of the free C-terminal end of A beta(42). The generated Mab A beta1.1 is indeed specific for the C-terminal end of A beta(42) to which it binds with high affinity. Mab A beta1.1 recognizes the epitope...

IgE-Binding Epitope Mapping and Tissue Localization of the Major American Cockroach Allergen Per a 2.

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Lee, Mey Fann; Chang, Chia Wei; Song, Pei Pong; Hwang, Guang Yuh; Lin, Shyh Jye; Chen, Yi Hsing

2015-07-01

Cockroaches are the second leading allergen in Taiwan. Sensitization to Per a 2, the major American cockroach allergen, correlates with clinical severity among patients with airway allergy, but there is limited information on IgE epitopes and tissue localization of Per a 2. This study aimed to identify Per a 2 linear IgE-binding epitopes and its distribution in the body of a cockroach. The cDNA of Per a 2 was used as a template and combined with oligonucleotide primers specific to the target areas with appropriate restriction enzyme sites. Eleven overlapping fragments of Per a 2 covering the whole allergen molecule, except 20 residues of signal peptide, were generated by PCR. Mature Per a 2 and overlapping deletion mutants were affinity-purified and assayed for IgE reactivity by immunoblotting. Three synthetic peptides comprising the B cell epitopes were evaluated by direct binding ELISA. Rabbit anti-Per a 2 antibody was used for immunohistochemistry. Human linear IgE-binding epitopes of Per a 2 were located at the amino acid sequences 57-86, 200-211, and 299-309. There was positive IgE binding to 10 tested Per a 2-allergic sera in 3 synthetic peptides, but none in the controls. Immunostaining revealed that Per a 2 was localized partly in the mouth and midgut of the cockroach, with the most intense staining observed in the hindgut, suggesting that the Per a 2 allergen might be excreted through the feces. Information on the IgE-binding epitope of Per a 2 may be used for designing more specific diagnostic and therapeutic approaches to cockroach allergy.

Identification of critical residues of linear B cell epitope on Goodpasture autoantigen.

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Xiao-yu Jia

Full Text Available The autoantigen of anti-glomerular basement membrane (GBM disease has been identified as the non-collagenous domain 1 of α3 chain of type IV collagen, α3(IVNC1. Our previous study revealed a peptide on α3(IVNC1 as a major linear epitope for B cells and potentially nephrogenic, designated as P14 (α3129-150. This peptide has also been proven to be the epitope of auto-reactive T cells in anti-GBM patients. This study was aimed to further characterize the critical motif of P14.16 patients with anti-GBM disease and positive anti-P14 antibodies were enrolled. A set of truncated and alanine substituted peptides derived from P14 were synthesized. Circulating antibodies against the peptides were detected by enzyme linked immunosorbent assay (ELISA.We found that all sera with anti-P14 antibodies reacted with the 13-mer sequence in the C-terminus of P14 (P14c exclusively. The level of antibodies against P14 was highly correlated with the level of antibodies against P14c (r=0.970, P<0.001. P14c was the core immunogenic region and the amino acid sequence (ISLWKGFSFIMFT was highly hydrophobic. Each amino acid residue in P14c was sequentially replaced by alanine. Three residues of glycine142, phenylalanine143, and phenylalanine145 were identified crucial for antibody binding based on the remarkable decline (P<0.001 of antibody reaction after each residue replacement.We defined GFxF (α3142, 143,145 as the critical motif of P14. It may provide some clues for understanding the etiology of anti-GBM disease.

Mimotopes selected by biopanning with high-titer HIV-neutralizing antibodies in plasma from Chinese slow progressors

Directory of Open Access Journals (Sweden)

Xiaoli Zhang

Full Text Available OBJECTIVE: One approach to identifying HIV-1 vaccine candidates is to dissect the natural antiviral immune response in treatment-naïve individuals infected for over ten years, considered slow progressor patients (SPs. It is suspected that SP plasma has strongly neutralizing antibodies (NAb targeting specific HIV viral epitopes. METHODS: NAbs levels of 11 HIV-1-infected SPs were detected by PBMC-based neutralization assays. To investigate SP NAb epitope, this study used a biopanning approach to obtain mimotopes of HIV-1 that were recognized by SP plasma NAbs. IgG was purified from hightiter NAb SP plasma, and used as the ligand for three rounds of biopanning to select HIV-specific mimotopes from a phage-displayed random peptide library. Double-antibody sandwich ELISA, competitive inhibition assays, and peptide sequence analysis were used to evaluate the characteristics of phage-borne mimotopes. RESULTS: SPs had significantly more plasma neutralizing activity than typical progressors (TPs (p = 0.04. P2 and P9 plasma, which have highest-titer HIV-NAb, were selected as ligands for biopanning. After three rounds of biopanning, 48 phage clones were obtained, of which 22 clones were consistent with requirement, binding with HIV-1 positive plasma and unbinding with HIV-1 negative plasma. Compared with linear HIV-1 protein sequence and HIV-1 protein structure files, only 12 clones were possible linear mimotopes of NAbs. In addition, the C40 clone located in gp41 CHR was found to be a neutralizing epitope, which could inhibit pooled HIV-1 positive plasma reaction. CONCLUSION: Biopanning of serum IgG can yield mimotopes of HIV-1-related antigen epitopes. This methodology provides a basis for exploration into HIV-1-related antigen-antibody interactions and furthers NAb immunotherapy and vaccine design.

Antibody informatics for drug discovery

DEFF Research Database (Denmark)

Shirai, Hiroki; Prades, Catherine; Vita, Randi

2014-01-01

to the antibody science in every project in antibody drug discovery. Recent experimental technologies allow for the rapid generation of large-scale data on antibody sequences, affinity, potency, structures, and biological functions; this should accelerate drug discovery research. Therefore, a robust bioinformatic...... infrastructure for these large data sets has become necessary. In this article, we first identify and discuss the typical obstacles faced during the antibody drug discovery process. We then summarize the current status of three sub-fields of antibody informatics as follows: (i) recent progress in technologies...... for antibody rational design using computational approaches to affinity and stability improvement, as well as ab-initio and homology-based antibody modeling; (ii) resources for antibody sequences, structures, and immune epitopes and open drug discovery resources for development of antibody drugs; and (iii...

Identification of murine T-cell epitopes in Ebola virus nucleoprotein

International Nuclear Information System (INIS)

Simmons, Graham; Lee, Anee; Rennekamp, Andrew J.; Fan Xin; Bates, Paul; Shen Hao

2004-01-01