Neutralizing anti-diphtheria toxin scFv produced by phage display

BACKGROUND

Diphtheria can be prevented by vaccination, but some epidemics occur in several places, and diphtheria's threat is considerable. Administration of diphtheria antitoxin (DAT) produced from hyperimmunized animals is the most common treatment. Recombinant human antibody fragments such as single-chain variable fragments (scFv) produced by phage display library may introduce an interesting approach to overcome the limitations of the traditional antibody therapy. In the present study, B cells of immunized volunteers were used to construct a human single-chain fragment (HuscFv) library.

MATERIALS AND METHODS

The library was constructed with the maximum combination of heavy and light chains. As an antigen, Diphtheria toxoid (DTd) was used in four-round phage bio-panning to select phage clones that display DTd bound HuscFv from the library. After panning, individual scFv clones were selected. Clones that were able to detect DTd in an initial screening assay were transferred to Escherichia coli HB2151 to express the scFvs and purification was followed by Ni metal ion affinity chromatography. Toxin neutralization test was performed on Vero cells. The reactivity of the soluble scFv with diphtheria toxin were done and affinity calculation based on Beatty method was calculated.

RESULTS

The size of the constructed scFv library was calculated to be 1.3 × 106 members. Following four rounds of selection, 40 antibody clones were isolated which showed positive reactivity with DTd in an ELISA assay. Five clones were able to neutralize DTd in Vero cell assay. These neutralizing clones were used for soluble expression and purification of scFv fragments. Some of these soluble scFv fragments show neutralizing activity ranging from 0.6 to 1.2 µg against twofold cytotoxic dose of diphtheria toxin. The affinity constant of the selected scFv antibody was determined almost 107 M-1.

CONCLUSION

This study describes the prosperous construction and isolation of scFv from the immune library, which specifically neutralizes diphtheria toxin. The HuscFv produced in this study can be a potential candidate to substitute the animal antibody for treating diphtheria and detecting toxins.

Development of Recombinant Antibody by Yeast Surface Display Technology

Recombinant antibodies have emerged as powerful tools in various fields, including therapeutics, diagnostics, and research applications. The selection of high-affinity antibodies with desired specificity is a crucial step in the development of recombinant antibody-based products. In recent years, yeast surface display technology has gained significant attention as a robust and versatile platform for antibody selection. This graphical review provides an overview of the yeast surface display technology and its applications in recombinant antibody selection. We discuss the key components involved in the construction of yeast surface display libraries, including the antibody gene libraries, yeast host strains, and display vectors. Furthermore, we highlight the strategies employed for affinity maturation and optimization of recombinant antibodies using yeast surface display. Finally, we discuss the advantages and limitations of this technology compared to other antibody selection methods. Overall, yeast surface display technology offers a powerful and efficient approach for the selection of recombinant antibodies, enabling the rapid generation of high-affinity antibodies for various applications.

Targeting cerebral diseases with enhanced delivery of therapeutic proteins across the blood-brain barrier

INTRODUCTION

Cerebral diseases have been threatening public physical and psychological health in the recent years. With the existence of the blood-brain barrier (BBB), it is particularly hard for therapeutic proteins like peptides, enzymes, antibodies, etc. to enter the central nervous system (CNS) and function in diagnosis and treatment in cerebral diseases. Fortunately, the past decade has witnessed some emerging strategies of delivering macromolecular therapeutic proteins across the BBB.

AREAS COVERED

Based on the structure, functions, and substances transport mechanisms, various enhanced delivery strategies of therapeutic proteins were reviewed, categorized by molecule-mediated delivery strategies, carrier-mediated delivery strategies, and other delivery strategies.

EXPERT OPINION

As for molecule-mediated delivery strategies, development of genetic engineering technology, optimization of protein expression and purification techniques, and mature of quality control systems all help to realize large-scale production of recombinant antibodies, making it possible to apply to the clinical practice. In terms of carrier-mediated delivery strategies and others, although nano-carriers/adeno-associated virus (AAV) are also promising candidates for delivering therapeutic proteins or genes across the BBB, some issues still remain to be further investigated, including safety concerns related to applied materials, large-scale production costs, quality control standards, combination therapies with auxiliary delivery strategies like focused ultrasound, etc.

Application of Baculovirus Expression Vector system (BEV) for COVID-19 diagnostics and therapeutics: a review

BACKGROUND

The baculovirus expression vector system has been developed for expressing a wide range of proteins, including enzymes, glycoproteins, recombinant viruses, and vaccines. The availability of the SARS-CoV-2 genome sequence has enabled the synthesis of SARS-CoV2 proteins in a baculovirus-insect cell platform for various applications. The most cloned SARS-CoV-2 protein is the spike protein, which plays a critical role in SARS-CoV-2 infection. It is available in its whole length or as subunits like S1 or the receptor-binding domain (RBD). Non-structural proteins (Nsps), another recombinant SARS-CoV-2 protein generated by the baculovirus expression vector system (BEV), are used in the identification of new medications or the repurposing of existing therapies for the treatment of COVID-19. Non-SARS-CoV-2 proteins generated by BEV for SARS-CoV-2 diagnosis or treatment include moloney murine leukemia virus reverse transcriptase (MMLVRT), angiotensin converting enzyme 2 (ACE2), therapeutic proteins, and recombinant antibodies. The recombinant proteins were modified to boost the yield or to stabilize the protein.

CONCLUSION

This review covers the wide application of the recombinant protein produced using the baculovirus expression technology for COVID-19 research. A lot of improvements have been made to produce functional proteins with high yields. However, there is still room for improvement and there are parts of this field of research that have not been investigated yet.

Phage display-derived immunorecognition elements LSPR nanobiosensor for peptide hormone glycine-extended gastrin 17 detection

The current study intended to evaluate two types of biorecognition element (BRE), namely recombinant antibody fragments and M13 bacteriophage-displayed antibody fragments, where protein L and electrostatic interactions were used to respectively conjugated antibodies and bacteriophages on AuNPs. The functionalization process was examined by DLS to monitor the changes in the size and zeta potential. The formation of the BRE-G17-Gly immunological complexes was manifested by aggregation (confirmed by FE-SEM) and color change from red to dark blue visible to the naked eye. Local refractive index variations of functionalized AuNPs were monitored by a UV - vis spectrophotometer, showing increasing size and decreasing zeta potential in all stages. The calibration plot was developed in the concentration range 1-5 µg/mL and the limit of detection (LOD) was 1 µg/mL. The LSRP nanobiosensor in combination with the phage-based BRE was an affordable and simple approach, as it was able to eliminate the time-consuming and costly step of extracting antibodies. Contrary to the traditional immunoassays, this method does not require additional amplification, e.g., enzymatic, to read the result. The proposed LSPR nanobiosensor model can be adapted to detect a wide range of pathogens, viruses, and biomarkers in the shortest possible time.

Expression and purification of a novel single-chain diabody (scDb-hERG1/β1) from Pichia pastoris transformants

In the last decades, protein engineering has developed particularly in biotechnology and pharmaceutical field. In particular, the engineered antibody subclass has arisen. The single chain diabody format (scDb), conjugating small size with antigen specificity, offers versatility representing a gold standard for a variety of applications, spacing from research to diagnostics and therapy. Along with such advantages, comes the challenge of optimizing their production, improving expression systems, purification procedures and stability. All such parameters are detrimental for protein production in general and above all for recombinant antibody expression, which has to be fine-tuned, choosing a proper protein-expression host and adjusting expression protocols accordingly. In the present paper, we present data regarding the production and purification of a single chain diabody directed against the macromolecular complex hERG1/β1 integrin. We focus on the expression of clones deriving from the transformation of Pichia pastoris yeast cells. In particular, we compare two different clones arose from two separate transformation processes, demonstrating that both are suitable for proper protein expression. Moreover, we have set up an expression protocol and compared the yields obtained using two purification machines: Akta Pure and Akta Start, with a positive outcome.

Single-cell approaches to investigate B cells and antibodies in autoimmune neurological disorders

Autoimmune neurological disorders, including neuromyelitis optica spectrum disorder, anti-N-methyl-D-aspartate receptor encephalitis, anti-MOG antibody-associated disorders, and myasthenia gravis, are clearly defined by the presence of autoantibodies against neurological antigens. Although these autoantibodies have been heavily studied for their biological activities, given the heterogeneity of polyclonal patient samples, the characteristics of a single antibody cannot be definitively assigned. This review details the findings of polyclonal serum and CSF studies and then explores the advances made by single-cell technologies to the field of antibody-mediated neurological disorders. High-resolution single-cell methods have revealed abnormalities in the tolerance mechanisms of several disorders and provided further insight into the B cells responsible for autoantibody production. Ultimately, several factors, including epitope specificity and binding affinity, finely regulate the pathogenic potential of an autoantibody, and a deeper appreciation of these factors may progress the development of targeted immunotherapies for patients.

Nanobodies: The "Magic Bullets" in therapeutics, drug delivery and diagnostics

Antibodies represent a well-established class of clinical diagnostics for medical applications as well as essential research and biotechnological tools. Although both polyclonal and monoclonal antibodies are indispensable reagents in basic research and diagnostics but both of them have their limitations. Hence, there is urgent need to develop strategies aimed at production of alternative scaffolds and recombinant antibodies of smaller dimensions that could be easily produced, selected and manipulated. Unlike conventional antibodies, members of Camelidae and sharks produce antibodies composed only of heavy chains with small size, high solubility, thermal stability, refolding capacity and good tissue penetration in vivo. The discovery of these naturally occurring antibodies having only heavy-chain in Camelidae family and their further development into small recombinant nanobodies represents an attractive alternative in drug delivery, diagnostics and imaging. Nanobody derivatives are soluble, stable, versatile, have unique refolding capacities, reduced aggregation tendencies and high-target binding capabilities. They can be genetically customized to target enzymes, transmembrane proteins or molecular interactions. Their ability to recognize recessed antigenic sites has been attributed to their smaller size and the ability of the extended CDR3 loop to quickly penetrate into such epitopes. With the advent of molecular engineering and phage display technology, they can be of potential use in molecular imaging, drug delivery and therapeutics for several major diseases. In this review we present the recent advances in nanobodies for modulating immune functions, for targeting cancers, viruses, toxins and microbes as well as their utility as diagnostic and biosensor tools.

Hydrophobic interaction chromatography as polishing step enables obtaining ultra-pure recombinant antibodies

Hydrophobic interaction chromatography is a versatile method to polish antibodies. Here, we present a polishing procedure in order to obtain an ultra-pure preparation of antitumor necrosis factor (TNF) alpha IgG1. Hydrophobic interaction chromatography (HIC) was used with Toyopearl® Phenyl 650M adsorbent in the presence of ammonium sulfate. Adsorption isotherms, breakthrough curves and chromatographic runs were carried out. The eluted antibody was recovered with 99.9 % purity and 96.2 % yield. In the main peak, aggregates, host cell proteins (HCP) and DNA content were below the limit of detection of the analytical methods used. Thus, the method proposed here shows potential to be employed in a downstream process when an ultra-pure antibody preparation is required.

A recombinant antibody toolbox for Dictyostelium discoideum

Objective

The amoeba Dictyostelium discoideum has been a valuable model organism to study numerous facets of eukaryotic cell biology, such as cell motility, cell adhesion, macropinocytosis and phagocytosis, host–pathogen interactions and multicellular development. However, the relative small size of the Dictyostelium community hampers the production and distribution of reagents and tools, such as antibodies, by commercial vendors.

Results

For the past 5 years, our laboratory has worked to promote an increased use of recombinant antibodies (rAbs) by academic laboratories. Here we report our efforts to ensure that Dictyostelium researchers have access to rAbs. Using hybridoma sequencing and phage display techniques, we generated a panel of recombinant antibodies against D. discoideum antigens, providing a useful and reliable set of reagents for labelling and characterization of proteins and subcellular compartments in D. discoideum, accessible to the entire Dictyostelium community.

Engineering Antibodies with C-Terminal Sortase-Mediated Modification for Targeted Nanomedicine

The current advances in nanoengineered materials coupled with the precise targeting capability of recombinant antibodies can create nanoscale diagnostics and therapeutics which show enhanced accumulation and extended retention at a target tissue. Smaller antibodies such as single-chain variable fragments (scFv) preserve the selective and strong binding of their parent antibody to their antigen with the benefits of low immunogenicity, more efficient tissue penetration and easy introduction of functional residues suitable for site-specific conjugation. This is of high importance as nonspecific antibody modification often involves attachment to free cysteine or lysine amino acids which may reside in the active site, leading to reduced antigen binding.In this chapter, we outline a facile and versatile chemoenzymatic approach for production of targeted nanocarrier scFv conjugates using the bacterial trans-peptidase Sortase A (Srt A). Srt A efficiently mediates sequence-specific peptide ligation under mild conditions and has few undesirable side reactions. We first describe the production, purification and characterization of Srt A enzyme and a scFv construct which targets activated platelets, called scFv_{anti-GPIIb/IIIa}. Following this, our protocol illustrates the chemoenzymatic modification of the antibody at the C-terminus with an orthogonal click chemistry linker. This avoids any random attachment to the biologically active antigen binding site of the antibody. Finally, we describe the modification of a nanoparticle surface with scFv attachment via two methods: (1) direct Sortase-mediated conjugation; or (2) a two-step system which consists of scFv Sortase-mediated conjugation followed by strain promoted azide-alkyne cycloaddition. Finally, methodology is described to assess the successful assembly of targeted particles.

Rapid purification of billions of circulating CD19+ B cells directly from leukophoresis samples

The study of the biology and function of B cells, or the dissection and in vitro creation of enormous recombinant antibody repertoires, requires the isolation of large numbers of pure CD19+ B cells. The StraightFrom^® Leukopak CD19 MicroBead Kit was recently introduced as a fast and robust kit to isolate human CD19+ B cells. This uses paramagnetic microbeads conjugated to high-affinity anti-CD19 monoclonal antibodies to bind B cells in leukapheresis (Leukopak) samples. The overall purity of the isolated cells, together with the characterization of the different CD19+ subclasses, was assessed by flow cytometry using a recombinant (REAffinity) antibody panel, revealing that the method allowed the recovery of over 93% of CD19+ B cells without any pre-purification step. This enables the relatively straightforward purification of all the circulating CD19+ B cells in a single donor.

Construction of Chicken Antibody Libraries

Recombinant antibody libraries based on chicken immunoglobulin genes are potentially valuable sources of phage displayed scFvs for use in veterinary diagnostics and research. The libraries described in this chapter are based on chicken variable heavy and light chain immunoglobulin genes joined by a short flexible linker cloned in the phagemid vector pHEN1. The resulting phagemids produce either scFvs displayed on the surface of the fusion phage subsequent to co-infection with helper phage, or soluble scFvs following IPTG induction. This chapter provides detailed and proven methods for the construction of such libraries.

Phage Display and Selections on Cells

Antibody identification by phage display on protein or peptide targets is well established and many protocols are available. But there are many targets that cannot be expressed recombinantly or, like peptides, do not reflect correct folding of the protein. Most of these targets are cell surface receptors. Here, we describe a protocol for a panning strategy on cells to obtain specific binders to cell surface receptors. A depletion step is included to prevent enrichment of antibodies that bind to unwanted targets. Each step of the protocol is explained and variations of this protocol are given.

Recombinant Antibodies to Arm Cytotoxic Lymphocytes in Cancer Immunotherapy

Immunotherapy has the potential to support and expand the body's own armamentarium of immune effector functions, which have been circumvented during malignant transformation and establishment of cancer and is presently considered to be the most promising treatment option for cancer patients. Recombinant antibody technologies have led to a multitude of novel antibody formats, which are in clinical development and hold great promise for future therapies. Among these formats, bispecific antibodies are extremely versatile due to their high efficacy to recruit and activate anti-tumoral immune effector cells, their excellent safety profile, and the opportunity for use in combination with cellular therapies. This review article summarizes the latest developments in cancer immunotherapy using immuno-engagers for recruiting T cells and NK cells to the tumor site. In addition to antibody formats, malignant cell targets, and immune cell targets, opportunities for combination therapies, including check point inhibitors, cytokines and adoptive transfer of immune cells, will be summarized and discussed.

Albumin-binding domain from Streptococcus zooepidemicus protein Zag as a novel strategy to improve the half-life of therapeutic proteins

Recombinant antibody fragments belong to the promising class of biopharmaceuticals with high potential for future therapeutic applications. However, due to their small size they are rapidly cleared from circulation. Binding to serum proteins can be an effective approach to improve pharmacokinetic properties of short half-life molecules. Herein, we have investigated the Zag albumin-binding domain (ABD) derived from Streptococcus zooepidemicus as a novel strategy to improve the pharmacokinetic properties of therapeutic molecules. To validate our approach, the Zag ABD was fused with an anti-TNFα single-domain antibody (sdAb). Our results demonstrated that the sdAb-Zag fusion protein was highly expressed and specifically recognizes human, rat and mouse serum albumins with affinities in the nanomolar range. Moreover, data also demonstrated that the sdAb activity against the therapeutic target (TNFα) was not affected when fused with Zag ABD. Importantly, the Zag ABD increased the sdAb half-life ∼39-fold (47min for sdAb versus 31h for sdAb-Zag). These findings demonstrate that the Zag ABD fusion is a promising approach to increase the half-life of small recombinant antibodies molecules without affecting their therapeutic efficacy. Moreover, the present study strongly suggests that the Zag ABD fusion strategy can be potentially used as a universal method to improve the pharmokinetics properties of many others therapeutics proteins and peptides in order to improve their dosing schedule and clinical effects.

Insights into the chicken IgY with emphasis on the generation and applications of chicken recombinant monoclonal antibodies

The advantages of chicken (Gallus gallus domesticus) antibodies as immunodiagnostic and immunotherapeutic biomolecules has only been recently recognized. Even so, chicken antibodies remain less-well characterized than their mammalian counterparts. This review aims at providing a current overview of the structure, function, development and generation of chicken antibodies. Additionally, brief but comprehensive insights into current knowledge pertaining to the immunogenetic framework and diversity-generation of the chicken immunoglobulin repertoire which have contributed to the establishment of recombinant chicken mAb-generating methods are discussed. Focus is provided on the current methods used to generate antibodies from chickens with added emphasis on the generation of recombinant chicken mAbs and its derivative formats. The advantages and limitations of established protocols for the generation of chicken mAbs are highlighted. The various applications of recombinant chicken mAbs and its derivative formats in immunodiagnostics and immunotherapy are further detailed.

Purification of Antibodies Using Affinity Chromatography

Affinity chromatography permits the isolation of a target analyte from a complex mixture and can be utilized to purify proteins, carbohydrates, drugs, haptens, or any analyte of interest once an affinity pair is available. It involves the exploitation of specific interactions between a binding affinity pair, such as those between an antibody and its associated antigen, or between any ligand and its associated binding receptor/protein. With the discovery of protein A in 1970, and, subsequently protein G and L, immuno-affinity chromatography has grown in popularity and is now the standard methodology for the purification of antibodies which may be implemented for a selection of different applications such as immunodiagnostics. This chapter is designed to inform the researcher about the basic techniques involved in the affinity chromatography-based purification of monoclonal, polyclonal, and recombinant antibodies. Examples are provided for the use of protein A and G. In addition, tables are provided that allow the reader to select the most appropriate protein for use in the isolation of their antibody.

Plasma protein profiling in a stage defined pancreatic cancer cohort - Implications for early diagnosis

Pancreatic ductal adenocarcinoma (PDAC) is a disease where detection preceding clinical symptoms significantly increases the life expectancy of patients. In this study, a recombinant antibody microarray platform was used to analyze 213 Chinese plasma samples from PDAC patients and normal control (NC) individuals. The cohort was stratified according to disease stage, i.e. resectable disease (stage I/II), locally advanced (stage III) and metastatic disease (stage IV). Support vector machine analysis showed that all PDAC stages could be discriminated from controls and that the accuracy increased with disease progression, from stage I to IV. Patients with stage I/II PDAC could be discriminated from NC with high accuracy based on a plasma protein signature, indicating a possibility for early diagnosis and increased detection rate of surgically resectable tumors.

Selection of Recombinant Human Antibodies

Since the development of therapeutic antibodies the demand of recombinant human antibodies is steadily increasing. Traditionally, therapeutic antibodies were generated by immunization of rat or mice, the generation of hybridoma clones, cloning of the antibody genes and subsequent humanization and engineering of the lead candidates. In the last few years, techniques were developed that use transgenic animals with a human antibody gene repertoire. Here, modern recombinant DNA technologies can be combined with well established immunization and hybridoma technologies to generate already affinity maturated human antibodies. An alternative are in vitro technologies which enabled the generation of fully human antibodies from antibody gene libraries that even exceed the human antibody repertoire. Specific antibodies can be isolated from these libraries in a very short time and therefore reduce the development time of an antibody drug at a very early stage.In this review, we describe different technologies that are currently used for the in vitro and in vivo generation of human antibodies.

Lentiviral Vectors for the Engineering of Implantable Cells Secreting Recombinant Antibodies

The implantation of genetically modified cells is considered for the chronic delivery of therapeutic recombinant proteins in vivo. In the context of gene therapy, the genetic engineering of cells faces two main challenges. First, it is critical to generate expandable cell sources, which can maintain stable high productivity of the recombinant protein of interest over time, both in culture and after transplantation. In addition, gene transfer techniques need to be developed to engineer cells synthetizing complex polypeptides, such as recombinant monoclonal antibodies, to broaden the range of potential therapeutic applications. Here, we provide a workflow for the use of lentiviral vectors as a flexible tool to generate antibody-producing cells. In particular, lentiviral vectors can be used to genetically engineer the cell types compatible with encapsulation devices protecting the implanted cells from the host immune system. Detailed methods are provided for the design and production of lentiviral vectors, optimization of cell transduction, as well as for the quantification and quality control of the produced recombinant antibody.

Identification of an unstable 4-hydroxynoneal modification on the 20S proteasome subunit α7 by recombinant antibody technology

Numerous cellular functions rely on an active proteasome allowing degradation of damaged or misfolded proteins. Therefore changes in the proteasomal activity have important physiological consequences. During oxidative stress the production of free radicals can result in the formation of 4-hydroxynonenal (HNE) following lipid peroxidiation. The HNE moiety is highly reactive and via a nucleophilic attack readily forms covalent links to cysteine, histidine and lysine side chains. However, as the chemical properties of these amino acids differ, so does the kinetics of the reactions. While covalent linkage through Michael addition is well established, reversible and unstable associations have only been indicated in a few cases. In the present study we have identified an unstable HNE adduct on the α7 subunit of the 20S proteasome using phage display of recombinant antibodies. This recombinant antibody fragment recognized HNE modified proteasomes in vitro and showed that this epitope was easily HNE modified, yet unstable, and influenced by experimental procedures. Hence unstable HNE-adducts could be overlooked as a regulatory mechanism of proteasomal activity and a participating factor in the decreased proteasomal activity associated with oxidative stress.

Modern affinity reagents: Recombinant antibodies and aptamers

Affinity reagents are essential tools in both basic and applied research; however, there is a growing concern about the reproducibility of animal-derived monoclonal antibodies. The need for higher quality affinity reagents has prompted the development of methods that provide scientific, economic, and time-saving advantages and do not require the use of animals. This review describes two types of affinity reagents, recombinant antibodies and aptamers, which are non-animal technologies that can replace the use of animal-derived monoclonal antibodies. Recombinant antibodies are protein-based reagents, while aptamers are nucleic-acid-based. In light of the scientific advantages of these technologies, this review also discusses ways to gain momentum in the use of modern affinity reagents, including an update to the 1999 National Academy of Sciences monoclonal antibody production report and federal incentives for recombinant antibody and aptamer efforts. In the long-term, these efforts have the potential to improve the overall quality and decrease the cost of scientific research.

Antigen-specific immunomodulation for type 1 diabetes by novel recombinant antibodies directed against diabetes-associates auto-reactive T cell epitope

The trimolecular complex composed of autoreactive T-cell receptor, MHC class II, and an autoantigenic peptide plays a central role in the activation of pathogenic Islet-specific CD4+ T cells in type 1 diabetes (T1D). We isolated and characterized novel antibodies against autoreactive T-cell epitopes associated with T1D. Our antibodies mimic the specificity of the T-cell receptor (TCR), while binding MHC class II/peptide complexes in an autoantigen peptide specific, MHC-restricted manner. The isolated TCR-like antibodies were directed against the minimal T-cell epitope GAD-555-567 in the context of the HLA-DR4-diabetic-associated molecule. A representative high-affinity TCR-like antibody clone (G3H8) enabled the detection of intra- and extra-cellular DR4/GAD-555-567 complexes in antigen presenting cells. I561M single mutation at the central position (P5) of the GAD-555-567 peptide abolished the binding of G3H8 to the DR4/GAD complex, demonstrating its high fine TCR-like specificity. The G3H8 TCR-like antibody significantly inhibited GAD-555-567 specific, DR4 restricted T-cell response in vitro and in vivo in HLA-DR4 transgenic mice. Our findings constitute a proof-of-concept for the utility of TCR-like antibodies as antigen-specific immunomodulation agents for regulating pathogenic T-cells and suggest that TCR-like antibodies targeting autoreactive MHC class II epitopes are valuable research tools that enable studies related to antigen presentation as well as novel therapeutic agents that may be used to modulate autoimmune disorders such as T1D.

AXM mutagenesis: an efficient means for the production of libraries for directed evolution of proteins

Affinity maturation is an important part of the recombinant antibody development process. There are several well-established approaches for generating libraries of mutated antibody genes for affinity maturation, but these approaches are generally too laborious or expensive to allow high-throughput, parallel processing of multiple antibodies. Here, we describe a scalable approach that enables the generation of libraries with greater than 10(8) clones from a single Escherichia coli transformation. In our method, a mutated DNA fragment is produced using PCR conditions that promote nucleotide misincorporation into newly synthesized DNA. In the PCR reaction, one of the primers contains at least three phosphorothioate linkages at its 5' end, and treatment of the PCR product with a 5' to 3' exonuclease is used to preferentially remove the strand synthesized with the non-modified primer, resulting in a single-stranded DNA fragment. This fragment then serves as a megaprimer to prime DNA synthesis on a uracilated, circular, single-stranded template in a Kunkel-like mutagenesis reaction that biases nucleotide base-changes between the megaprimer and uracilated DNA sequence in favor of the in vitro synthesized megaprimer. This method eliminates the inefficient subcloning steps that are normally required for the construction of affinity maturation libraries from randomly mutagenized antibody genes.