scholarly journals Focused peptide library screening as a route to a superior affinity ligand for antibody purification

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Krištof Bozovičar ◽  
Barbara Jenko Bizjan ◽  
Anže Meden ◽  
Jernej Kovač ◽  
Tomaž Bratkovič
Keyword(s):  
Binding Capacity ◽  
Protein A ◽  
Downstream Processing ◽  
Phage Display Library ◽  
Enrichment Ratio ◽  
Peptide Ligand ◽  
Staphylococcal Protein A ◽  
Dynamic Binding ◽  
Linear Peptide

AbstractAffinity chromatography is the linchpin of antibody downstream processing and typically relies on bacterial immunoglobulin (Ig)-binding proteins, epitomized by staphylococcal protein A-based ligands. However, such affinity ligands are fairly costly and suffer from chemical instability, leading to ligand denaturation and leaching from chromatographic support. Innovations in this area are aimed at developing robust and highly selective antibody ligands capable of withstanding harsh column sanitization conditions. We report the development and first-stage characterization of a selective short linear peptide ligand of the IgG Fc region capable of capturing all four IgG subclasses. The ligand was discovered through in vitro directed evolution. A focused phage-display library based on a previously identified peptide lead was subjected to a single-round screen against a pool of human IgG. The hits were identified with next-generation sequencing and ranked according to the enrichment ratio relative to their frequency in the pre-screened library. The top enriched peptide GSYWYNVWF displaying highest affinity for IgG was coupled to bromohydrin-activated agarose beads via a branched linker. The resulting affinity matrix was characterized with a dynamic binding capacity of approx. 43 mg/mL, on par with commercially employed protein A-based resin.

scholarly journals Optimization of Sequence, Display, and Mode of Operation of IgG-Binding Peptide Ligands to Develop Robust, High-Capacity Affinity Adsorbents That Afford High IgG Product Quality

2019 ◽  
Vol 20 (1) ◽  
pp. 161 ◽  
Author(s):  
Tuhidul Islam ◽  
Amith D. Naik ◽  
Yasuhiro Hashimoto ◽  
Stefano Menegatti ◽  
Ruben G. Carbonell
Keyword(s):  
Binding Capacity ◽  
Protein A ◽  
Chinese Hamster ◽  
High Capacity ◽  
Alkaline Solutions ◽  
Peptide Ligand ◽  
Dynamic Binding ◽  
Ligand Density ◽  
Host Cell Proteins ◽  
Igg Binding

This work presents the use of peptide ligand HWRGWV and its cognate sequences to develop affinity adsorbents that compete with Protein A in terms of binding capacity and quality of the eluted product. First, the peptide ligand was conjugated to crosslinked agarose resins (WorkBeads) at different densities and using different spacer arms. The optimization of ligand density and display resulted in values of static and dynamic binding capacity of 85 mg/mL and 65 mg/mL, respectively. A selected peptide-WorkBeads adsorbent was utilized for purifying Mabs from Chinese Hamster Ovary (CHO) cell culture supernatants. The peptide-WorkBeads adsorbent was found able to withstand sanitization with strong alkaline solutions (0.5 M NaOH). The purity of the eluted product was consistently higher than 95%, with logarithmic removal value (LRV) of 1.5 for host cell proteins (HCPs) and 4.0 for DNA. HCP clearance was significantly improved by adding a post-load washing step with either 0.1 M Tris HCl pH 9 or 1 M NaCl. The cognate peptide of HWRGWV, constructed by replacing arginine (R) with citrulline, further increased the HCP LRV to 2.15. The peptide-based adsorbent also showed a remarkable performance in terms of removal of Mab aggregates; unlike Protein A, in fact, HWRGWV was found to bind only monomeric IgG. Collectively, these results demonstrate the potential of peptide-based adsorbents as alternative to Protein A for the purification of therapeutic antibodies.

scholarly journals Engineering of novel Staphylococcal Protein A ligands to enable milder elution pH and high dynamic binding capacity

2014 ◽  
Vol 1362 ◽  
pp. 180-185 ◽  
Author(s):  
Timothy M. Pabst ◽  
Ronnie Palmgren ◽  
Annika Forss ◽  
Jelena Vasic ◽  
Mariko Fonseca ◽  
...  
Keyword(s):  
Binding Capacity ◽  
Protein A ◽  
Staphylococcal Protein A ◽  
Dynamic Binding ◽  
Staphylococcal Protein ◽  
Dynamic Binding Capacity ◽  
High Dynamic

scholarly journals An In Vitro Study of the Effect of Viburnum opulus Extracts on Key Processes in the Development of Staphylococcal Infections

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1758
Author(s):  
Urszula Wójcik-Bojek ◽  
Joanna Rywaniak ◽  
Przemysław Bernat ◽  
Anna Podsędek ◽  
Dominika Kajszczak ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Protein A ◽  
In Vitro Study ◽  
Alternative Methods ◽  
Staphylococcal Protein A ◽  
Viburnum Opulus ◽  
Staphylococcal Infections ◽  
Diet Supplements ◽  
Drug Resistant Strains

Staphylococcus aureus is still one of the leading causes of both hospital- and community-acquired infections. Due to the very high percentage of drug-resistant strains, the participation of drug-tolerant biofilms in pathological changes, and thus the limited number of effective antibiotics, there is an urgent need to search for alternative methods of prevention or treatment for S. aureus infections. In the present study, biochemically characterized (HPLC/UPLC–QTOF–MS) acetonic, ethanolic, and water extracts from fruits and bark of Viburnum opulus L. were tested in vitro as diet additives that potentially prevent staphylococcal infections. The impacts of V. opulus extracts on sortase A (SrtA) activity (Fluorimetric Assay), staphylococcal protein A (SpA) expression (FITC-labelled specific antibodies), the lipid composition of bacterial cell membranes (LC-MS/MS, GC/MS), and biofilm formation (LIVE/DEAD BacLight) were assessed. The cytotoxicity of V. opulus extracts to the human fibroblast line HFF-1 was also tested (MTT reduction). V. opulus extracts strongly inhibited SrtA activity and SpA expression, caused modifications of S. aureus cell membrane, limited biofilm formation by staphylococci, and were non-cytotoxic. Therefore, they have pro-health potential. Nevertheless, their usefulness as diet supplements that are beneficial for the prevention of staphylococcal infections should be confirmed in animal models in the future.

scholarly journals The Synergistic Effect of Nicotine and Staphylococcus aureus on Peri-Implant Infections

2021 ◽  
Vol 9 ◽  
Author(s):  
Yao Hu ◽  
Wen Zhou ◽  
Chengguang Zhu ◽  
Yujie Zhou ◽  
Qiang Guo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Synergistic Effects ◽  
Protein A ◽  
Treated Group ◽  
Combination Group ◽  
Staphylococcal Protein A ◽  
Receptor Activator ◽  
And Staphylococcus Aureus

Smoking is considered a key risk factor for implant survival; however, how it interacts with the pathogens in peri-implant infections is not clear. Here, we identified that nicotine, the key component of cigarette smoking, can interact with Staphylococcus aureus and synergistically induce peri-implant infections in a rat osteolysis model. The nicotine–S. aureus combination group increased the gross bone pathology, osteolysis, periosteal reactions, and bone resorption compared to the nicotine or S. aureus single treated group (p < 0.05). Nicotine did not promote the proliferation of S. aureus both in vitro and in vivo, but it can significantly upregulate the expression of staphylococcal protein A (SpA), a key virulence factor of S. aureus. The nicotine–S. aureus combination also synergistically activated the expression of RANKL (receptor activator of nuclear factor-kappa B ligand, p < 0.05) to promote the development of peri-implant infections. The synergistic effects between nicotine and S. aureus infection can be a new target to reduce the peri-implant infections.

scholarly journals Lymphocyte transformation induced by autologous cells. V. generation of immunologic memory and specificity during the autologous mixed lymphocyte reaction

1977 ◽  
Vol 146 (6) ◽  
pp. 1833-1838 ◽  
Author(s):  
ME Weksler ◽  
R Kozak
Keyword(s):  
T Lymphocytes ◽  
Lymphocyte Proliferation ◽  
Mixed Lymphocyte Reaction ◽  
Protein A ◽  
Lymphocyte Transformation ◽  
Cell Mediated Immunity ◽  
Staphylococcal Protein A ◽  
Autologous Mixed Lymphocyte Reaction ◽  
Proliferation In Vitro

Lymphocyte proliferation in vitro may follow antigen recognition and serve as a correlate of cell-mediated immunity. Lymphocyte proliferation can also be simulated by nonimmune mechanisms as, for example, following culture with plant lectin, lipopolysaccharides, or staphylococcal protein A (1). The autologous mixed lymphocyte reaction (MLR) refers to the proliferation of T lymphocytes cultured with autologous mon-T lymphocytes (2,3). The purpose of this study was to determine whether lymphocyte proliferation in the autologous MLR results from immune or nonimmune mechanisms. We have shown that the autologous MLR has two classical attributes of an immune phenomenon: memory and specificity.

Changes in Circulating Immune Complexes in Tumour Patient Serum after in Vitro or ex Vivo Affinity Chromatography of Blood Plasma or whole Blood over Immunoglobulinbinding Staphylococcal Protein A-Sepharose

1984 ◽  
Vol 7 (1) ◽  
pp. 23-26 ◽  
Author(s):  
L. Håkansson ◽  
J. Hed ◽  
L. Baldetorp ◽  
S. Eneström ◽  
S. Jonsson ◽  
...  
Keyword(s):  
Blood Plasma ◽  
Immune Complexes ◽  
Whole Blood ◽  
Ex Vivo ◽  
Protein A ◽  
Circulating Immune Complexes ◽  
Staphylococcal Protein A ◽  
Lower Affinity ◽  
Tumour Patient

Circulating immune complexes (CIC) were determined in tumour patient sera using three methods. One is based on PEG-precipitation, one on C1q-reactivity, and one on protein A-reactivity. About 25-30% of the sera were positive in at least one of the tests. Incubation of serum with protein A-Sepharose in vitro removed PEG-precipitable CIC from most sera, whereas C1q-reactive CICs had a much lower affinity to protein A. The protein A-reactive complexes showed considerable variation in their binding to protein A-Sepharose, and in some sera the amount of these CICs was actually increased. Similar changes in protein A-reactive CIC were also found during ex vivo treatment of tumour patients with immune adsorption. It is proposed that the binding of immune complexes to protein A can result in remodelling of protein A itself. Results from ultracentrifugation and fractionated PEG-precipitation support this hypothesis.

PRTX-100 Inhibits Platelet Phagocytosis In Vitro.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1081-1081 ◽  
Author(s):  
Chris Yatko ◽  
Christopher Herrem ◽  
Samia Siddiqui ◽  
Victor S. Sloan
Keyword(s):  
Mononuclear Cells ◽  
Therapeutic Option ◽  
Protein A ◽  
Flow Cytometric Analysis ◽  
Human Platelets ◽  
Staphylococcal Protein A ◽  
Human Monocytes ◽  
Peripheral Blood Mononuclear ◽  
Vitro Assay

Abstract Background: In idiopathic thrombocytopenic purpura (ITP), autoantibodies bind to platelets which are then phagocytosed by monocytes/macrophages and removed by the reticuloendothelial system. PRTX-100 (Staphylococcal protein A) is being investigated for the treatment of ITP. Objective: To assess the effect of PRTX-100 on phagocytosis of platelets in an in vitro assay. Methods: Human monocytes were isolated from whole blood peripheral blood mononuclear cells (PBMCs) by adherence and cultured for 6 days in RPMI + 5% human serum. 48 hours prior to phagocytosis assay, PRTX-100 was added at 250, 25, and 2.5ng/ml. Human platelets were labeled with a fluorescent (PerCP) lipophilic dye and opsonized with an antibody to MHC Class I (W632). 2×10−5 monocytes were co-cultured with 2×10−7 labeled platelets for 1 hour at 37 ° C. All conditions were performed in triplicate. After an hour, phycoerythrin (PE) labeled anti-CD61 antibody was added to assess surface bound platelets versus ingested platelets. Phagocytosis was determined by flow cytometric analysis. The monocyte population was gated upon by forward and side scatter properties, then verified by staining with CD14-FITC. Percent phagocytosis was calculated as the fraction of ingested platelets (PerCP +/CD61−) to the total PerCP population (PerCP +/CD61−) + ( PerCP+/CD61+) within the gated monocyte population. Results: PRTX-100 inhibits the phagocytosis of W632 opsonized platelets by human monocytes. Phagocytosis of W632 opsonized platelets was 40%, while phagocytosis in the presence of PRTX-100 at concentrations of 250, 25, and 2.5ng/ml was 18.3%, 23%, and 24.3%, respectively. Phagocytosis at 250ng/ml and 25ng/ml was significantly different from control phagocytosis with p values of 0.014 and 0.001 respectively by Student’s t test. Conclusions: PRTX-100 inhibits the phagocytosis of platelets by monocytes, the effector limb of ITP. Prevention of platelet phagocytosis is an important treatment goal in ITP. PRTX-100 has been shown to be generally safe and well-tolerated in a phase I study in healthy volunteers (J Clin Pharmacol, in press). PRTX -100 is a promising therapeutic option for ITP and deserves further study. Effect of PRTX-100 on In Vitro Phagocytosis of Opsonized Human Platelets Effect of PRTX-100 on In Vitro Phagocytosis of Opsonized Human Platelets

scholarly journals Staphylococcus aureus Protein A Promotes Immune Suppression

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Scott D. Kobayashi ◽  
Frank R. DeLeo
Keyword(s):  
Staphylococcus Aureus ◽  
B Cell ◽  
Immune Evasion ◽  
Bacterial Infections ◽  
Binding Capacity ◽  
Protein A ◽  
Strong Support ◽  
The United States ◽  
Content Type

ABSTRACTStaphylococcus aureusis a prominent cause of human infections worldwide and is notorious for its ability to acquire resistance to antibiotics. Methicillin-resistantS. aureus(MRSA), in particular, is endemic in hospitals and is the most frequent cause of community-associated bacterial infections in the United States. Inasmuch as treatment options for severe MRSA infections are limited, there is need for a vaccine that protects against such infections. However, recent efforts to generate a staphylococcal vaccine have met with little success in human clinical trials. These failures are somewhat puzzling, since the vaccine antigens tested promote opsonophagocytosisin vitroand confer protection in animal infection models. One possibility is that the pathogen inhibits (and/or fails to elicit) the development of protective immunity in humans. Indeed,S. aureusproduces numerous molecules that can potentially promote immune evasion, including protein A (SpA), an immunoglobulin (Ig)-binding protein present on the bacterial surface and freely secreted into the extracellular environment. SpA binds the Fc region of antibody and the Fab regions of the B-cell receptor, processes that are known to block opsonophagocytosis and cause B-cell deathin vitro. In a recent study, Falugi et al. [F. Falugi, H. K. Kim, D. M. Missiakas, and O. Schneewind, mBio 4(5):e00575-13, 2013] showed that vaccination withspamutantS. aureusstrains lacking antibody Fc- and/or Fab-binding capacity protects against subsequent challenge with the USA300 epidemic strain. The findings provide strong support for the idea that SpA promotesS. aureusimmune evasionin vivoand form the foundation for a new approach in our efforts to develop a vaccine that prevents severeS. aureusinfections.

scholarly journals Prevalence of fosfomycin resistance and gene mutations in clinical isolates of methicillin-resistant Staphylococcus aureus

2020 ◽  
Author(s):  
Yi-Chien Lee ◽  
Pao-Yu Chen ◽  
Jann-Tay Wang ◽  
Shan-Chwen Chang
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Agents ◽  
Genetic Relatedness ◽  
Protein A ◽  
Gene Mutations ◽  
Resistance Rate ◽  
Staphylococcal Protein A ◽  
Methicillin Resistant ◽  
Fosfomycin Resistance

Abstract Background: Fosfomycin exhibits excellent in vitro activity against multidrug-resistant pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Increasing fosfomycin resistance among clinical MRSA isolates was reported previously, but little is known about the genetic mechanisms of fosfomycin resistance.Methods: All MRSA isolates, collected in 2002 and 2012 by the Taiwan Surveillance of Antimicrobial Resistance (TSAR) program, were used in this study. Susceptibility to various antimicrobial agents, including fosfomycin, was determined by broth microdilution. Genetic determinants of fosfomycin resistance, including fosB carriage and murA, glpT and uhpT mutations, were investigated using PCR and sequencing of amplicons. Staphylococcal protein A (spa) typing was also performed to determine the genetic relatedness of MRSA isolates.Results: A total of 969 MRSA strains, 495 in the year 2002 and 474 in the year 2012, were analyzed. The overall in vitro susceptibility was 8.2% to erythromycin, 18.0% to clindamycin, 29.0% to tetracycline, 44.6% to ciprofloxacin, 57.5% to trimethoprim/sulfamethoxazole, 86.9% to rifampicin, 92.9% to fosfomycin and 100% to linezolid and vancomycin. A significant increase in the fosfomycin resistance rate was observed from 3.4% in 2002 to 11.0% in 2012. Of 68 fosfomycin-resistant MRSA isolates, 12 harbored the fosB gene, and expression of murA, uhpT, and glpT mutations was noted in 11, 59, and 66 isolates, respectively. Combination of mutations of uhpT and glpT genes (58 isolates) was the most prevalent resistant mechanism. The vast majority of the fosfomycin-resistant MRSA isolates belonged to spa type t002.Conclusions: An increased fosfomycin resistance rate of MRSA isolates was observed in our present study, mostly due to mutations in the glpT and uhpT genes. Clonal spread probably contributed to the increased fosfomycin resistance.

scholarly journals Towards a Recombinant Vaccine against Diphtheria Toxin

1998 ◽  
Vol 66 (2) ◽  
pp. 418-423 ◽  
Author(s):  
Karin Lobeck ◽  
Pascal Drevet ◽  
Michel Léonetti ◽  
Cécile Fromen-Romano ◽  
Frédéric Ducancel ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Diphtheria Toxin ◽  
Protein A ◽  
Vero Cells ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Surface Receptors ◽  
Linear Peptide ◽  
Recombinant Fragments

ABSTRACT Two recombinant fragments of diphtheria toxin (DT) were fused to an engineered tandem repeat of the immunoglobulin (Ig) binding domain of protein A, called ZZ. These fragments are (i) the receptor binding domain (DTR), which comprises amino acids 382 to 535 of DT, and (ii) a linear peptide (DT168–220) which comprises residues 168 to 220 of the loop between fragment A and fragment B of DT. The fusion proteins were produced in Escherichia coli and purified by affinity chromatography. In vitro experiments showed that the DTR domain is responsible for the capacity of ZZ-DTR to bind to Vero cells and is capable of inhibiting the cytotoxicity of DT for these cells. These findings suggest that DTR binds to the cell surface receptors of DT and hence adopts a conformation that is similar to that of the receptor binding domain of DT. We compared the capacities of ZZ-DTR, ZZ-DT168–220, and a chemically detoxified form of DT currently used for vaccination to elicit antibodies in rabbits. The toxoid was more immunogenic than ZZ-DT168–220, which in turn was more immunogenic than ZZ-DTR. However, ZZ-DT168–220 antiserum was poorly efficient at neutralizing DT cytotoxicity on Vero cells, whereas ZZ-DTR antiserum was only 15-fold less potent than anti-DT antisera.

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