| 1. |
- Hu, Francis Jingxin, 1986-, et al.
(författare)
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Combination of phage and Gram-positive bacterial display of human antibody repertoires enables isolation of functional high affinity binders
- 2018
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Ingår i: New Biotechnology. - : Elsevier. - 1871-6784 .- 1876-4347. ; 45, s. 80-88
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Tidskriftsartikel (refereegranskat)abstract
- Surface display couples genotype with a surface exposed phenotype and thereby allows screening of gene-encoded protein libraries for desired characteristics. Of the various display systems available, phage display is by far the most popular, mainly thanks to its ability to harbour large size libraries. Here, we describe the first use of a Gram-positive bacterial host for display of a library of human antibody genes which, when combined with phage display, provides ease of use for screening, sorting and ranking by flow cytometry. We demonstrate the utility of this method by identifying low nanomolar affinity scFv fragments towards human epidermal growth factor receptor 2 (HER2). The ranking and performance of the scFv isolated by flow sorting in surface-immobilised form was retained when expressed as soluble scFv and analysed by biolayer interferometry, as well as after expression as full-length antibodies in mammalian cells. We also demonstrate the possibility of using Gram-positive bacterial display to directly improve the affinity of the identified binders via an affinity maturation step using random mutagenesis and flow sorting. This combined approach has the potential for a more complete scan of the antibody repertoire and for affinity maturation of human antibody formats.
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| 2. |
- Hu, Francis Jingxin, 1986-, et al.
(författare)
-
Phage and Gram-positive bacterial display of human antibody repertoires enables isolation of functional high affinity binders
-
Ingår i: New Biotechnology. - 1871-6784 .- 1876-4347.
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Surface display couples genotype with a surface exposed phenotype and thereby allows for screening of gene-encoded protein libraries for desired characteristics. Of the various display systems, phage display is by far the most popular, mainly thanks to its ability to harbor large library sizes. Here, we describe the first use of a grampositive host for display of a library of human antibody genes. The method allows for swift generation of binders by combining phage and gram-positive display, for its ease of use for screening, sorting and ranking by flow cytometry. We demonstrate the utility of this method by identifying specific low nanomolar scFv towards human HER2. The ranking and performance of the scFv isolated by flow sorting in surface immobilized form was retained when expressed as soluble scFv and analyzed by biolayer interferometry as well as after expression as full-length antibodies in mammalian cells. We also show the possibility to use gram-positive display to directly improve the affinity of the identified binders via an affinity maturation step using random mutagenesis and flow sorting. We believe this combined approach has the potential for a more complete scan of the antibody repertoire and for swift affinity maturation of human antibody formats.
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| 3. |
- Hu, Francis Jingxin, 1986-, et al.
(författare)
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SAMURAI (Solid-phase Assisted Mutagenesis by Uracil Restricted Ablation In vitro) for Antibody Affinity Maturation and Paratope Mapping
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Mutagenesis libraries are essential for combinatorial protein engineering. Despite improve- ments in gene synthesis and directed mutagenesis, current methodologies still have limitations regarding the synthesis of intact antibody scFv genes and simultaneous diversification of all six CDRs. Here, we de- scribe the generation of mutagenesis libraries for antibody affinity maturation, using a cell-free solid-phase technique for annealing of single-strand mutagenic oligonucleotides. This procedure consists of PCR-based incorporation of uracil into a wild-type template, bead-based capture, and elution of single-strand DNA, and in vitro uracil excision enzyme based degradation of the template DNA. Our approach enabled rapid (8 hours) mutagenesis and automated cloning of 50 position specific alanine mutants for mapping of a scFv antibody paratope. We further exemplify our method by generating affinity maturation libraries with di- versity introduced in critical, nonessential, or all CDR positions randomly. Assessment with Illumina deep sequencing showed >99% functional diversity in two libraries and the ability to diversify all CDR positions simultaneously. Selections of the libraries with bacterial display and deep sequencing evaluation of the selection output showed that diversity introduced in non-essential positions allowed quicker enrichment of improved binders compared to the other two diversification strategies.
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| 4. |
- Hu, Francis Jingxin, 1986-, et al.
(författare)
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SAMURAI (Solid-phase Assisted Mutagenesis by Uracil Restriction for Accurate Integration) for antibody affinity maturation and paratope mapping
- 2019
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Ingår i: Nucleic Acids Research. - : OXFORD UNIV PRESS. - 0305-1048 .- 1362-4962. ; 47:6
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Tidskriftsartikel (refereegranskat)abstract
- Mutagenesis libraries are essential for combinatorial protein engineering. Despite improvements in gene synthesis and directed mutagenesis, current methodologies still have limitations regarding the synthesis of complete antibody single-chain variable fragment (scFv) genes and simultaneous diversification of all six CDRs. Here, we describe the generation of mutagenesis libraries for antibody affinity maturation using a cell-free solid-phase technique for annealing of single-strand mutagenic oligonucleotides. The procedure consists of PCR-based incorporation of uracil into a wild-type template, bead-based capture, elution of single-strand DNA, and in vitro uracil excision enzyme based degradation of the template DNA. Our approach enabled rapid (8 hours) mutagenesis and automated cloning of 50 position-specific alanine mutants for mapping of a scFv antibody paratope. We further exemplify our method by generating affinity maturation libraries with diversity introduced in critical, nonessential, or all CDR positions randomly. Assessment with Illumina deep sequencing showed less than 1% wild-type in two libraries and the ability to diversify all CDR positions simultaneously. Selections of the libraries with bacterial display and deep sequencing evaluation of the selection output showed that diversity introduced in non-essential positions allowed for a more effective enrichment of improved binders compared to the other two diversification strategies.
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| 5. |
- Hu, Francis Jingxin, 1986-, et al.
(författare)
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SPUX - A Solid Phase Uracil Excision Method for Antibody Affinity Maturation and Paratope Mapping
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Mutagenesis libraries are the heart of combinatorial protein engineering where proteins such as antibodies are evolved for improved functionality. Despite recent improvements in gene synthesis and selection methodologies, current methods still fail to provide practical means for synthesis of complete antibody scFv and screening of theoretical diversities, hence forcing the user to focused diversity screening and assembly of shorter oligos to avoid synthesis errors and maximize library functionality. Here we demonstrate a way to generate highly functional tailored mutagenesis libraries for efficient antibody affinity maturation using a rapid cell-free solid phase cloning method with single strand diversity oligonucleotides. For this we are utilizing a combination of a high-fidelity polymerase for PCR-based incorporation of Uracil into a wild-type template, bead-based solid-phase technology for elution of single strand DNA, oligonucleotide annealing, extension and automation, and an uracil excision enzyme cocktail for in vitro degradation of template DNA to minimize background. Our method allowed for fast (8 hours) mutagenesis and automated cloning of a complete set of 50 position specific alanine-mutations for mapping of the paratope of a scFv antibody in a single robot run. We further exemplify our method by generating and stratifying a set of antibody scFv affinity maturation libraries with targeted diversity into critical or nonessential paratope positions, as well as by a complete randomization in all positions. The libraries were subjected to bacterial surface display selections and output was followed by Illumina deep sequencing and binding analysis by SPR. The functional quality of our libraries were high, with a yield of >99% functional diversity in the case for two of our libraries. We were further able to target all positions in all loops with diversity, and we could show the ability to target all six loops with diversity at the same time. The comparison of different library focus showed us that scFv libraries with diversity targeted to non-essential enhancing paratope positions more quickly rendered enrichment of improved binders compared to random diversity or paratope-targeted libraries. Surprisingly several of the improved binders from the random library had beneficial mutations in the same positions targeted by the smaller focused non-essential enhancing residue focused library indicating a possible benefit of focusing diversity to these spots. We believe our method for construction of libraries with site directed mutagenesis to be a viable way for generation of functional and diverse genetic libraries, particularly suitable for affinity maturation and paratope mapping of antibodies.
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| 6. |
- Hu, Francis Jingxin, 1986-
(författare)
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Utilizing Solid Phase Cloning, Surface Display And Epitope Information for Antibody Generation and Characterization
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibodies have become indispensable tools in diagnostics, research and as therapeutics. There are several strategies to generate monoclonal antibodies (mAbs) in order to avoid the drawbacks of polyclonal antibodies (pAbs) for therapeutic use. Moreover, the growing interest in precision medicine requires a well-characterized target and antibody to predict the responsiveness of a treatment. This thesis describes the use of epitope information and display technologies to generate and characterize antibodies. In Paper I, we evaluated if the epitope information of a well-characterized pAb could be used to generate mAbs with retained binding characteristics. In Paper II, the epitope on the complement protein C5 towards Eculizumab was mapped with surface display, the results of which explained the non-responsiveness of Eculizumab treatment among a patient group due to a mutated C5 gene. With this in mind, we showed efficacy in treatment of the mutated C5 variants using a drug binding to another site on C5, suggesting that our approach can be used to guide treatment in precision medicine. In Paper III, a Gram-positive bacterial display platform was evaluated to complement existing platforms for selection of human scFv libraries. When combined with phage display, a thorough library screening and isolation of nano-molar binders was possible. In Paper IV, a solid phase method for directed mutagenesis was developed to generate functional affinity maturation libraries by simultaneous targeting of all six CDRs. The method was also used to create numerous individual mutants to map the paratope of the parent scFv. The paratope information was used to create directed libraries and deep sequencing of the affinity maturation libraries confirmed the viability of the combination approach. Taken together, precise epitope/paratope information together with display technologies have the potential to generate attractive therapeutic antibodies and direct treatment in precision medicine.
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| 7. |
- Volk, Anna-Luisa, et al.
(författare)
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Epitope mapping of antibodies using bacterial cell surface display of gene fragment libraries
- 2018
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Ingår i: Epitope Mapping Protocols. - New York, NY : Humana Press. ; , s. 141-157
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Bokkapitel (refereegranskat)abstract
- The unique property of specific high affinity binding to more or less any target of interest has made antibodies tremendously useful in numerous applications. Hence, knowledge of the precise binding site (epitope) of antibodies on the target protein is one of the most important features for understanding its performance and determining its reliability in immunoassays. Here, we describe an updated protocol for high-resolution method for mapping epitopes of antibodies based on bacterial surface expression of antigen fragments followed by antibody-based flow cytometric analysis. Epitopes are determined by DNA sequencing of the sorted antibody-binding cells followed by sequence alignment back to the antigen sequence. The method described here has been useful for the mapping of both monoclonal and polyclonal antibodies with varying sizes of epitopes.
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