抗体已成为最有希望的癌症、传染性和炎症疾病的治疗手段之一。 传统产生抗体的方法旷日费时。 在SIAIS抗体筛选平台，我们开发了高质量，非高库容的合成人类抗体库，用于生物药物发现。各种形式的高库容合成抗体库展示于M13噬菌体系统上，可进行针对多种靶点蛋白的高通量筛选并产生对应的抗体先导药物。 抗体筛选平台旨在建立学术界与工业界的合作关系，为高质量的药物开发提供抗体资源。
SAC由来自多伦多大学和上海科技大学的着名抗体科学家Sachdev S. Sidhu教授领衔。已建立了一支经验丰富的抗体科学家团队，专注于先导抗体筛选和功能验证。 我们使用先进的人类合成抗体技术开发抗体药物。 并与SIAIS的高通量筛选，蛋白质，影像，分析和生物医学大数据平台积极合作。 SIAIS高度优化的抗体技术和支持使SAC拥有领先的抗体开发能力。
1.Libraries of synthetic antibodies:
A major advance in oncology over the last decade has been the emergence of monoclonal antibodies as effective therapeutics. Our lab has been involved in developing the latest frontier in antibody therapeutics: synthetic antibody libraries with man-made antigen-binding sites.
|[Fig1 – hybridoma vs. synthetic abs]: Construction of antibody libraries from natural or synthetic diversity. (a) Antibody libraries from natural repertoires are derived by harvesting VH and VL genes from naive B cells. B-cell maturation (1) involves the rearrangement of germline antibody genes in pro-B cells to produce naive B cells that contain diverse, functional antibody genes61. The gene encoding the heavy chain is formed first by the joining of three diversity elements (VH, D and JH), which together encode the variable domain, and a constant element (Cμ), which encodes the constant region of immunoglobulin M (IgM). Subsequently, the gene encoding a κ (shown) or λ light chain is formed by the joining of two diversity elements (Vκ and Jκ, or Vλ and Jλ for λ light chains) that encode the variable domain and a constant segment (Cκ or Cλ) that encodes the constant domain. Gene segments that encode leader sequences (L) direct secretion of both chains. For library construction, mRNA from naive B cells is reverse transcribed to produce cDNA (2). VH and VL repertoires are amplified from the cDNA using PCR (3), and these are combined in a phage-display vector (4) to produce phage-displayed antibody repertoires (5). (b) For the construction of synthetic antibody repertoires, insights from structural and functional analyses of functional antibodies (1) are used to design synthetic oligonucleotides (2) that introduce chemically and spatially defined diversity into the CDR loops (3). The synthetic CDR repertoires are incorporated into defined VH and VL framework genes in phage-display vectors (4) to produce phage-displayed antibody repertoires (5).|
|2. Alternative antibody frameworks:|
Synthetic antibody technology gives the freedom to explore other frameworks for their ability to bind antigens. The full-length antibody framework consists of a constant region (Fc) and a variable region (Fab).
|[Fig2 – structure of IgG and domains]: Crystal structure of a full-length antibody (IgG), a heterotetramer of two heavy chains (yellow) and two light chains (blue). The antigen-binding site (red) is formed by six hypervariable loops (three each from the light and heavy chain) or CDRs. The antigen-binding unit (Fab) can be reduced further to an Fv, consisting of a VL and VH monomer where the two variable domains are linked, producing a stable scFv. The simplest antigen-binding unit is the VH domain, found in natural camelid antibodies. For synthetic antibody library construction, diversity is introduced into the CDR loops, and the remaining regions of the variable domains serve as a framework to maintain the structure of the antigen-binding site.|
|3. Generation of synthetic antibodies by high throughput phage display selections:|
To produce synthetic antibodies, our antibody libraries are displayed on phage screened against a desired target antigen in an in vitro setting. Thus, this technology allows for rapid affinity maturation and specificity optimization of the selected antibodies.
|[Fig3-High throughput flowchart]: Flow chart summary of the high-throughput Fab generation process|
|4. Modulation of cell signaling with synthetic antibodies, and antibodies as potential therapeutics and reagents for biological research:|
Some of the best targets for antibodies are cell surface receptors involved in signal transduction pathways. Several of these pathways are deregulated in cancer and other diseases, and have been the target of chemical drugs for a number of years.
|FIG4-Immunofluorescence staining with Fab-YSv1 (red) performed on A673 cells expressing murine VEGFGFP (green). VEGF-GFP and Fab-YSv1 staining co-localize in the extracellular space formed between cell-to-cell contacts (merge, yellow). The Fab-YSv1 staining was completely abolished bypre-incubation of the antibody with excess recombinant hVEGF (C VEGF panels). The scale bar represents 20 mm. (d) Immunoprecipitations performed on media collected from metabolically labeled A673 cells. Fab-YSv1 and monoclonal antibody A4.6.1 show comparable specificity, as evidenced by identical patterns of bands for precipitated hVEGF isoforms. Anti-GFP polyclonal antibody was used as a negative control|