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2021 ◽  
Vol 22 (15) ◽  
pp. 8288
Nadezhda Todorova ◽  
Miroslav Rangelov ◽  
Vanya Bogoeva ◽  
Vishnya Stoyanova ◽  
Anna Yordanova ◽  

We addressed the issue of C1q autoantigenicity by studying the structural features of the autoepitopes recognized by the polyclonal anti-C1q antibodies present in Lupus Nephritis (LN) sera. We used six fractions of anti-C1q as antigens and selected anti-idiotypic scFv antibodies from the phage library “Griffin.1”. The monoclonal scFv A1 was the most potent inhibitor of the recognition of C1q and its fragments ghA, ghB and ghC, comprising the globular domain gC1q, by the lupus autoantibodies. It was sequenced and in silico folded by molecular dynamics into a 3D structure. The generated 3D model of A1 elucidated CDR similarity to the apical region of gC1q, thus mapping indirectly for the first time a globular autoepitope of C1q. The VH CDR2 of A1 mimicked the ghA sequence GSEAD suggested as a cross-epitope between anti-DNA and anti-C1q antibodies. Other potential inhibitors of the recognition of C1q by the LN autoantibodies among the selected recombinant antibodies were the monoclonal scFv F6, F9 and A12.

2021 ◽  
Vol 21 (1) ◽  
Zahra Shadman ◽  
Safar Farajnia ◽  
Mohammad Pazhang ◽  
Mohammadreza Tohidkia ◽  
Leila Rahbarnia ◽  

Abstract Background Pseudomonas aeruginosa is the leading cause of nosocomial infections, especially in people with a compromised immune system. Targeting virulence factors by neutralizing antibodies is a novel paradigm for the treatment of antibiotic-resistant pseudomonas infections. In this respect, exotoxin A is one of the most potent virulence factors in P. aeruginosa. The present study was carried out to identify a novel human scFv antibody against the P. aeruginosa exotoxin A domain I (ExoA-DI) from a human scFv phage library. Methods The recombinant ExoA-DI of P. aeruginosa was expressed in E. coli, purified by Ni-NTA column, and used for screening of human antibody phage library. A novel screening procedure was conducted to prevent the elimination of rare specific clones. The phage clone with high reactivity was evaluated by ELISA and western blot. Results Based on the results of polyclonal phage ELISA, the fifth round of biopanning leads to the isolation of several ExoA-DI reactive clones. One positive clone with high affinity was selected by monoclonal phage ELISA and used for antibody expression. The purified scFv showed high reactivity with the recombinant domain I and full-length native exotoxin A. Conclusions The purified anti-exotoxin A scFv displayed high specificity against exotoxin A. The human scFv identified in this study could be the groundwork for developing a novel therapeutic agent to control P. aeruginosa infections.

2021 ◽  
Guangxu Xing ◽  
Yunshang Zhang ◽  
Fangyu Wang ◽  
Liuding Wen ◽  
Gaiping Zhang

Abstract A recombinant anti-enrofloxacin single-chain antibody (scFv) was produced for the detection of enrofloxacin. An immunized mouse phage display scFv library with a capacity of 2.35×109 CFU/mL was constructed and used for anti-enrofloxacin scFv screening. After four rounds of bio-panning, 10 positives were isolated and identified successfully. The highest positive scFv was expressed in E. coli BL21. Then, its recognition mechanisms were studied using the molecular docking method. The result showed the amino acid residues Leu121 were the key residues for the binding of ScFv to ENR. Based on the results of virtual mutation, the ScFv antibody was evolved by directional mutagenesis of contact amino acid residue Leu121 to Asn. After the expression and purification, an indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) based on the parental and mutant ScFv were established for enrofloxacin respectively. The IC50 value of the assay established with the ScFv mutant was 1.63 ng/mL, while the parental ScFv was 21.08 ng/mL, this result showed highly increased affinity with up to 12.9-folds improved sensitivity. The mean recovery for ENR ranged from 71.80% to 117.35% with 10.46% relative standard deviation between the intra-assay and the inter-assay. The results indicate that we have obtained a highly sensitive anti-ENR scFv by the phage library construction and directional evolution, and the scFv-based IC-ELISA is suitable for the detection of ENR residue in animal derived edible tissues and milk.

2021 ◽  
Andrew Yee ◽  
Manhong Dai ◽  
Stacy E. Croteau ◽  
Jordan A. Shavit ◽  
Steven W. Pipe ◽  

SummaryBackgroundCorrection of von Willebrand factor (VWF) deficiency with replacement products containing VWF can lead to the development of anti-VWF alloantibodies (i.e., VWF inhibitors) in patients with severe von Willebrand disease (VWD).ObjectiveLocate inhibitor-reactive regions within VWF using phage display.MethodsWe screened a phage library displaying random, overlapping fragments covering the full length VWF protein sequence for binding to a commercial anti-VWF antibody or to immunoglobulins from three type 3 VWD patients who developed VWF inhibitors in response to treatment with plasma-derived VWF. Immunoreactive phage clones were identified and quantified by next generation DNA sequencing (NGS).ResultsNGS markedly increased the number of phage analyzed for locating immunoreactive regions within VWF following a single round of selection and identified regions not recognized in previous reports using standard phage display methods. Extending this approach to characterize VWF inhibitors from three type 3 VWD patients (including two siblings homozygous for the same VWF gene deletion) revealed patterns of immunoreactivity distinct from the commercial antibody and between unrelated patients, though with notable areas of overlap. Alloantibody reactivity against the VWF propeptide is consistent with incomplete removal of the propeptide from plasma-derived VWF replacement products.ConclusionThese results demonstrate the utility of phage display and NGS to characterize diverse anti-VWF antibody reactivities.

2021 ◽  
Vol 37 ◽  
pp. 127835
Masahiro Hashimoto ◽  
Takayuki Miki ◽  
Iou Ven Chang ◽  
Hiroshi Tsutsumi ◽  
Hisakazu Mihara

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1225
Jiawen Cao ◽  
Tiantian Fan ◽  
Yanlian Li ◽  
Zhiyan Du ◽  
Lin Chen ◽  

WD40 is a ubiquitous domain presented in at least 361 human proteins and acts as scaffold to form protein complexes. Among them, WDR5 protein is an important mediator in several protein complexes to exert its functions in histone modification and chromatin remodeling. Therefore, it was considered as a promising epigenetic target involving in anti-cancer drug development. In view of the protein–protein interaction nature of WDR5, we initialized a campaign to discover new peptide-mimic inhibitors of WDR5. In current study, we utilized the phage display technique and screened with a disulfide-based cyclic peptide phage library. Five rounds of biopanning were performed and isolated clones were sequenced. By analyzing the sequences, total five peptides were synthesized for binding assay. The four peptides are shown to have the moderate binding affinity. Finally, the detailed binding interactions were revealed by solving a WDR5-peptide cocrystal structure.

2021 ◽  
Vol 12 ◽  
Nannan Wu ◽  
Tongyu Zhu

Nosocomial infections (NIs) are hospital-acquired infections which pose a high healthcare burden worldwide. The impact of NIs is further aggravated by the global spread of antimicrobial resistance (AMR). Conventional treatment and disinfection agents are often insufficient to catch up with the increasing AMR and tolerance of the pathogenic bacteria. This has resulted in a need for alternative approaches and raised new interest in therapeutic bacteriophages (phages). In contrast to the limited clinical options available against AMR bacteria, the extreme abundance and biodiversity of phages in nature provides an opportunity to establish an ever-expanding phage library that collectively provides sustained broad-spectrum and poly microbial coverage. Given the specificity of phage-host interactions, phage susceptibility testing can serve as a rapid and cost-effective method for bacterial subtyping. The library can also provide a database for routine monitoring of nosocomial infections as a prelude to preparing ready-to-use phages for patient treatment and environmental sterilization. Despite the remaining obstacles for clinical application of phages, the establishment of phage libraries, pre-stocked phage vials prepared to good manufacturing practice (GMP) standards, and pre-optimized phage screening technology will facilitate efforts to make phages available as modern medicine. This may provide the breakthrough needed to demonstrate the great potential in nosocomial infection management.

2021 ◽  
Vol 12 (1) ◽  
Daniel R. Monaco ◽  
Brandon M. Sie ◽  
Thomas R. Nirschl ◽  
Audrey C. Knight ◽  
Hugh A. Sampson ◽  

AbstractAllergic reactions occur when IgE molecules become crosslinked by antigens such as food proteins. Here we create the ‘AllerScan’ programmable phage display system to characterize the binding specificities of anti-allergen IgG and IgE antibodies in serum against thousands of allergenic proteins from hundreds of organisms at peptide resolution. Using AllerScan, we identify robust anti-wheat IgE reactivities in wheat allergic individuals but not in wheat-sensitized individuals. Meanwhile, a key wheat epitope in alpha purothionin elicits dominant IgE responses among allergic patients, and frequent IgG responses among sensitized and non-allergic patients. A double-blind, placebo-controlled trial shows that alpha purothionin reactivity, among others, is strongly modulated by oral immunotherapy in tolerized individuals. AllerScan may thus serve as a high-throughput platform for unbiased analysis of anti-allergen antibody specificities.

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