Phage display technology refers to a high-throughput in vitro screening technology for extracting required peptides/ proteins from colonies with mass mutants. Due to its high efficiency, practicability and convenience, it has been widely applied in pharmaceutical research and development, as well as target protein screening for active ingredients of traditional Chinese medicines. Target protein is the binding site of drug molecules in vivo, and good targets are the basis of excellent pharmaceuticals. This article summarizes the advance in studies on the phage display technology and its application in targeted protein screening for active ingredients of Chinese materia medica.
Binding Sites ; Cell Surface Display Techniques ; methods ; Drugs, Chinese Herbal ; chemistry ; Mass Screening ; methods ; Plant Extracts ; chemistry ; Proteins ; chemistry

OBJECTIVETo construct dengue virus-specific full-length fully human antibody libraries using mammalian cell surface display technique.

METHODSTotal RNA was extracted from peripheral blood mononuclear cells (PBMCs) from convalescent patients with dengue fever. The reservoirs of the light chain and heavy chain variable regions (LCκ and VH) of the antibody genes were amplified by RT-PCR and inserted into the vector pDGB-HC-TM separately to construct the light chain and heavy chain libraries. The library DNAs were transfected into CHO cells and the expression of full-length fully human antibodies on the surface of CHO cells was analyzed by flow cytometry.

RESULTSUsing 1.2 µg of the total RNA isolated from the PBMCs as the template, the LCκ and VH were amplified and the full-length fully human antibody mammalian display libraries were constructed. The kappa light chain gene library had a size of 1.45×10(4) and the heavy chain gene library had a size of 1.8×10(5). Sequence analysis showed that 8 out of the 10 light chain clones and 7 out of the 10 heavy chain clones randomly picked up from the constructed libraries contained correct open reading frames. FACS analysis demonstrated that all the 15 clones with correct open reading frames expressed full-length antibodies, which could be detected on CHO cell surfaces. After co-transfection of the heavy chain and light chain gene libraries into CHO cells, the expression of full-length antibodies on CHO cell surfaces could be detected by FACS analysis with an expressible diversity of the antibody library reaching 1.46×10(9) [(1.45×10(4)×80%)×(1.8×10(5)×70%)].

CONCLUSIONUsing 1.2 µg of total RNA as template, the LCκ and VH full-length fully human antibody libraries against dengue virus have been successfully constructed with an expressible diversity of 10(9).

Animals ; Antibodies, Viral ; CHO Cells ; Cell Surface Display Techniques ; Cricetinae ; Cricetulus ; Dengue Virus ; immunology ; Gene Library ; Genetic Vectors ; Humans ; Immunoglobulin Heavy Chains ; immunology ; Transfection

OBJECTIVETo construct full-length human bladder cancer-specific antibody libraries for efficient display of full-length antibodies on the surface of mammalian cells.

METHODSThe total RNA was isolated from peripheral blood mononuclear cells from patients with bladder cancer. The repertoires of IgG1 heavy chain variable region (VH) and Kappa light chain were amplified by RT-PCR using specific primers. The antibody genes were inserted into the vector pDGB-HC-TM to construct the bladder-cancer-specific antibody libraries of heavy chains and light chains. Ten clones from each library were randomly picked for gene sequencing and transient transfection into FCHO cells to analyze antibody display on mammalian cell surface by flow cytometry after staining with corresponding fluorescent labeled antibodies.

RESULTSThe libraries of bladder-cancer-specific antibody heavy chain (IgG1) and light chain (LCk) were successfully constructed. Seven out of the 10 clones randomly selected from the heavy chain library and 9 out of the 10 clones from the light chain library showed correct open reading frame, coding for 7 unique VH and 9 unique LCk. The combinatory library size reached 3.32×10(11).

CONCLUSIONWe have successfully constructed a full-length human bladder-cancer-specific antibody library with a combinatory diversity of 3.32×10(11) based on mammalian display technology, which can be used for screening monoclonal antibodies against bladder-cancer-associated antigens.

Amino Acid Sequence ; Animals ; Antibodies ; genetics ; Cell Surface Display Techniques ; Gene Library ; Humans ; Immunoglobulin Heavy Chains ; genetics ; Immunoglobulin kappa-Chains ; genetics ; Peptide Library ; Urinary Bladder Neoplasms ; genetics ; immunology

Acetylcholinesterase (AChE) plays a key role in the pesticide determination. However, the extraction of AChE from natural materials has the disadvantages of low yield, complex purification and poor stability. Therefore, the preparation of recombinant AChE with high performance becomes the hot topic of researchers in recent years. In this article we summarize the progress in the expression of recombinant AChE and the improvement of its analytical characteristic. Finally, we point out that the directed evolution strategy combined with surface display technology is the future trend on improving recombinant AChE activity.
Acetylcholinesterase ; biosynthesis ; chemistry ; genetics ; Baculoviridae ; genetics ; metabolism ; Cell Surface Display Techniques ; Cholinesterase Inhibitors ; analysis ; Evolution, Molecular ; Genetic Vectors ; genetics ; Pesticide Residues ; analysis ; Pichia ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics

We developed a new method for soluble expression of phage-displayed scFv antibody specific for zebrafish vitellogenin. The scFv antibody F5 could bind zebrafish vitellogenin specifically in phage-displayed form but not soluble form. The gene of scFv antibody F5 was cloned into vector pET 32a and transferred into Escherichia coli ori DE3. With inducible expression, soluble scFv antibody 32a-F5 was obtained successfully and could also specifically bind to zebrafish vitellogenin. The insoluble expression of phage-displayed scFv antibody was a common problem in the practical use of phage display. This study offered a feasible way to express soluble scFv antibodies with biological activity.
Amino Acid Sequence ; Animals ; Antibody Specificity ; Base Sequence ; Cell Surface Display Techniques ; Escherichia coli ; genetics ; metabolism ; Molecular Sequence Data ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Single-Chain Antibodies ; biosynthesis ; genetics ; immunology ; Solubility ; Vitellogenins ; immunology ; Zebrafish ; immunology ; metabolism

In this study, we are to produce the single chain variable fragment (scFv) antibodies against surface protein of hepatitis B virus (HBV) using antibody phage display technique. Balb/c mice were immunized with preS1 and cDNAs of heavy and light chains of splenic B cells from immunized mice were prepared using RT-PCR. Two cDNAs were linked with (64S) linker DNA under recombination PCR to produce single chain Fv DNA. After digestion of scFv DNA with Sp 1 and Not 1, the digested DNA was ligated into pCANTAB 5E and electroporated into E. coli XL1-Blue to prepare scFv-library. The size of library was 1 * 10' pfu/ml. Phage antibodies (phabs) against preS1 were rescued with M13K07 helper phages, and preS1-binders were selected through 3 times of panning using 96 well microtitre plates. Phage antibody clones were assayed directly for the ability to bind preS1 by ELISA. And then 7 phage antibody clones had high ELISA signals against preS1. Phabs from preS1-specific pMsc-17 had the strongest ELISA signal to preS1. Phabs from pMsc-17 were used for Western blot to preS1 and the results revealed that it was specific to preS1. To prepare the soluble scFv antibody, phabs from pMsc-17 were transfected into non-suppressor E. coli HB2151, and grown under 1 mM IPTG. Soluble scFv antibody was mainly accumulated in the periplasmic space, but small amount of antibody was secreted into culture media.
Animals ; Antibodies ; B-Lymphocytes ; Bacteriophages* ; Blotting, Western ; Cell Surface Display Techniques ; Clone Cells ; Culture Media ; Digestion ; DNA ; DNA, Complementary ; Enzyme-Linked Immunosorbent Assay ; Hepatitis B virus* ; Hepatitis B* ; Hepatitis* ; Isopropyl Thiogalactoside ; Mice* ; Periplasm ; Polymerase Chain Reaction ; Recombination, Genetic ; Single-Chain Antibodies*

BACKGROUND: To develop a novel treatment strategy for hepatitis B virus infection, a major cause of liver chirosis and cancer, we aimed to make human monoclonal antibodies inhibiting RNase H activity of P protein playing in important role in HBV replication. In this regard, phage display technology was employed and demonstrated as an efficient cloning method for human monoclonal antibody. So this study analysed the usability of human monoclonal antibody as protein based gene therapy. METHODS: RNase H of HBV was expressed as fusion protein with maltose binding protein and purified with amylose resin column. Single chain Fv (scFv) phage antibody library was constructed by PCR cloning using total RNAs of PBMC from 50 healthy volunteers. Binders to RNase H were selected with BIAcore 2000 from the constructed library, and purified as soluble antibody fragment. The affinity and sequences of selected antibody fragments were analyzed with BIAcore and ABI automatic sequencer, respectively. And finally RNase H activity inhibiting assay was carried out. RESULTS: Recombinant RNase H expressed in E. coli exhibited an proper enzyme activity. Naive library of 4.46 X 10(9) cfu was screened by BIAcore 2000. Two clones, RN41 and RN56, showed affinity of 4.5 X 10(-7) M and 1.9 X 10(-7) M, respectively. But RNase H inhibiting activity of RN41 was higher than that of RN56. CONCLUSION: We cloned human monoclonal antibodies inhibiting RNase H activity of P protein of HBV. These antibodies can be expected to be a good candidate for protein-based antiviral therapy by preventing a replication of HBV if they can be expressed intracellularly in HBV-infected hepatocytes.
Amylose ; Antibodies ; Antibodies, Monoclonal ; Bacteriophages* ; Cell Surface Display Techniques* ; Clone Cells ; Cloning, Organism ; Genetic Therapy ; Healthy Volunteers ; Hepatitis B virus* ; Hepatitis B* ; Hepatitis* ; Hepatocytes ; Humans* ; Immunoglobulin Fragments ; Liver ; Maltose-Binding Proteins ; Polymerase Chain Reaction ; Ribonuclease H* ; Ribonucleases* ; RNA ; Single-Chain Antibodies

OBJECTIVETo construct a rheumatoid arthritis-specific full-length fully human mammalian display antibody libraries.

METHODSPeripheral blood lymphocytes were isolated from patients with rheumatoid arthritis. The repertoires of kappa light chain (LCκ) and heavy chain variable region (VH) of the antibodies were amplified by RT-PCR. The amplified LCκ and VH genes were inserted into the vector pDGB-HC-TM separately, and the ligated libraries were transformed into competent E.coli TOPO-10 strain to construct the rheumatoid arthritis-specific antibody heavy and light chain libraries. 293T cells were co-transfected with the libraries and the full-length fully human antibody expressed on the surface of 293T cells were analyzed by flow cytometry.

RESULTSThe libraries of rheumatoid arthritis-specific antibody LCκ and heavy chain (IgG1) were constructed. The expression of full-length fully human antibody on the surface of 293T cells was confirmed by flow cytometry. With the rates of correct LCκ and heavy chain sequence insertion reaching 80% and 60%, respectively, as shown by DNA sequence analysis of the randomly selected clones, the libraries showed an expressible combinatory diversity of 6.13×10(10).

CONCLUSIONThe constructed libraries provide a useful platform for screening rheumatoid arthritis-specific antibodies.

Amino Acid Sequence ; Animals ; Antibodies ; genetics ; immunology ; Antibody Specificity ; Arthritis, Rheumatoid ; immunology ; Cell Surface Display Techniques ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; HEK293 Cells ; Humans ; Immunoglobulin G ; biosynthesis ; genetics ; Immunoglobulin Heavy Chains ; biosynthesis ; genetics ; Immunoglobulin kappa-Chains ; biosynthesis ; genetics ; Lymphocytes ; immunology ; metabolism ; Molecular Sequence Data ; Peptide Library ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Transfection