Phage antibody library technology in tumor therapy: a review / 生物工程学报

Tumor is a serious threat to human health. At present, surgical resection, chemoradiotherapy, targeted therapy and immunotherapy are the main therapeutic strategies. Monoclonal antibody has gradually become an indispensable drug type in the clinical treatment of cancer due to its high efficiency and low toxicity. Phage antibody library technology (PALT) is a novel monoclonal antibody preparation technique. The recombinant immunoglobulin variable region of heavy chain (VH)/variable region of light chain (VL) gene is integrated into the phage vector, and the antibody is expressed on the phage surface in the form of fusion protein to obtain a diverse antibody library. Through the process of adsorption-elution-amplification, the antibody library can be screened to obtain the antibody molecule with specific binding antigen as well as its gene sequence. PALT has the advantages of short antibody production cycle, strong plasticity of antibody structure, large antibody yield, high diversity and direct production of humanized antibodies. It has been used in screening tumor markers and preparation of antibody drugs for breast cancer, gastric cancer, lung cancer and liver cancer. This article reviews the recent progress and the application of PALT in tumor therapy.

Screening and identification of human anti-C3d single chain antibodies / 国际药学研究杂志

Objective: To screen human single chain antibodies against human C3d from phage-displayed single-chain variable fragment(scFv)library, and analyze their binding activities. Methods: The phage display library was exposed to 3-round selections in immunotubes coated with recombinant C3d at a decreasing concentration range and progressively stringent washing conditions. The positive clones were identified by ELISA, followed with sequencing to determine the specific genes which were then cloned intoex-pression vectors. The single chain antibodies were expressed in the FreeStyleTM 293-F system and harvested by affinity purification. The binding activities with recombinant C3d were determined by using Bio-Layer Interferometry technology. Results: These experiments resulted in three novel single chain antibodies(that is, A1, A3 and B6)against C3d with high affinity ranging from 22.7 to 171 pmol/ L. Conclusion: The high affinity human single chain antibodies against human C3d were obtained.

An overview on application of phage display technique in immunological studies

Phage display is very strong technique in drug discovery and development. Phage display has many applications in improving the immunological studies. Development of mono-clonal antibody, peptides, peptidomimetics and epitope mapping are main application of phage display. Selection of monoclonal antibody or peptides that are displayed on the surface of the phages can be occurred through biopanning process. In biopanning process phage library is incubated with antigen and particular phages can be identified and iso-lated. Increasing the stringency in the biopanning rounds can be help to select phages with high affinity and specificity. Here, we describe an overview of phage display application with focusing on monoclonal antibody production and epitope mapping.

Selection and identification of human monoantibody TRAb Fab fragment / 天津医药

Objective To select and express a human thyrotrophin receptor antibody (TRAb) Fab fragment from phage antibody library constructed with phage display technology. Methods With immobilized antigen, the reconstructed humanized TRAb Fab library was enriched by five rounds panning (adsorption-elution-amplification). The TSAb Fab and TBAb Fab fragment were selected by coated fusion proteins of hTSHRn and hTSHRc. The positive clones were identified and selected by Phage-ELISA. TRAb positive clones were identified by PCR and double restriction enzyme digestion. The soluble TRAb (TSAb, TBAb) Fab fragments were expressed. TRAb (TSAb, TBAb) Fab fragments were identified by Western blotting assay. The DNA fragment was sequenced from the positive clones. Results Following five rounds of biopanning, TRAb (TSAb,TBAb) Fab phage antibody was screened. The enrichment effect reached to 77 times and 94 times. The soluble TRAb (TSAb,TBAb) Fab antibodies were expressed from positive clones and identified by phage ELISA. Western blotting analysis showed that the phage displaying Fab had significant binding activity with antigens. These sequence analysis showed that all of the heavy chain Fd gene and light chain gene were derived from human immunoglobulin variable region. The light chain variable region of the monoclonal 48 was homologous to the immunoglobulin light chain Vλ homology of 94.4%, and the heavy chain variable region of the monoclonal 48 was homologous to the immunoglobulin heavy Fd chain VH4 homology of 88.9%. The light chain variable region of the monoclonal 56 was homologous to the immunoglobulin light chain Vλ homology of 95.6%, and the heavy chain variable region of the monoclonal 56 was homologous to the immunoglobulin heavy Fd chain VH3 homology of 84.6%. Conclusion We have successfully selected TRAb (TSAb, TBAb) Fab fragment from a human phage display immune antibody library.

An overview on application of phage display technique in immunological studies

Phage display is very strong technique in drug discovery and development. Phage display has many applications in improving the immunological studies. Development of monoclonal antibody, peptides, peptidomimetics and epitope mapping are main application of phage display. Selection of monoclonal antibody or peptides that are displayed on the surface of the phages can be occurred through biopanning process. In biopanning process phage library is incubated with antigen and particular phages can be identified and isolated. Increasing the stringency in the biopanning rounds can be help to select phages with high affinity and specificity. Here, we describe an overview of phage display application with focusing on monoclonal antibody production and epitope mapping.

Construction and screening of human phage display antibody library against lung adenocarcinoma / 第二军医大学学报

Objective:To construct human single-chain variable fragment (ScFv) antibody library, and screen out antibodies against lung adenocarcinoma from the library. Methods: The total RNA was isolated from tumor adjacent lymph nodes of the lung adenocarcinoma patients and was used to amplify VH and VL genes by RT-PCR. VH and VL genes was joined with a DNA linker by SOE-PCR to form the ScFv. The gel purified ScFv gene repertoires were cloned into the phage vector pCANTAB5E to construct the primary phage library. Panning against lung adenocarcinoma cell line A549 was performed for four rounds and the phage library was identified. Results: A recombinant phage antibody library was successfully constructed. The fourth phage harvest yielded 115 times as much as that of the first one. During affinity screening, the antibody was enriched with the increase of panning rounds. Positive reactions to A549 were detected in 7 of 10 randomly selected clones, with a positive rate of 70%. Conclusion: A human phage-display antibody library has been successfully constructed. The selected ScFv fragment can specifically bind to human lung adenocarcinoma cell line A549.

Screening, expression and characterization of single chain Fv (scFv) against basic fibroblast growth factor / 中华微生物学和免疫学杂志

Objective To obtain the specific human scFv basic fibroblast growth factor(bFGF)using phage antibody library technology. Methods The library was panned with human recombinant bFGF for 4 rounds. The antigen binding activities of random clones were tested by ELISA in order to select specific antibodies, which were then examined by DNA sequence analysis. Results The positive clone selected from the 104 random clones was able to bind bFGF specifically, while not able to bind other growth factors,such as aFGF, VEGF(vascular endothelial growth factor). By competition ELISA assay we found one clone 44 could inhibit bFGF binding to FGFR1. Conclusion Seven specific human phage antibody against bFGF was obtained by phage display technique, one clone could inhibit bFGF binding to its high affinity receptor FGFR1.

Screening and identification of neutralizated single-chain antibody of anti-glomerular basement membrane antibody / 中华微生物学和免疫学杂志

Objective To screen a human single-chain variable fragments(scFv)against antiGBM antibody.Methods Using phage display technique,the phage antibody library was panned by antiglomerular basement membrane(GBM)antibody which was coated in a micro-titer plate,one clone was found to have high affinity to anti-GBM antibody.The DNA sequence of the positive clone was determined.Results Along with the increase of rounds anti-GBM antibody specific phage antibody was highly enriched and screening efficiency was increased 137 folds than the firest round.ELISA and competition inhibition assay showed that the scFv had a specific combination character with anti-GBM antibody.DNA sequencing confirmed that the whole gene of scFv was 750 bp,and in accordance with humanized single-chain variable region antibody sequence structure.Conclusion The results suggested that the scFv fragment to anti-GBM antibody could be successfully selected by recombinant phage antibody technique,which will laid an experimental foundation for further research of the therapy of Goodpasture syndrome.

Screening and primary identification of anti-CCR7 scFv from large phage library / 中国药理学通报

Aim To screen and identify anti-CCR7 single chain fragments variable(scFv)from lager phage library and to detect the scFv efficiency.Methods The insert ratio of ScFv antibodies library was identified by PCR.The products digested by Sfi I/Not I double enzyme.Panning against breast cancer cell and CCR7 were performed four and three rounds respectively.Positive clones were transformed to E.coli HB2151, and their dissolvability was assayed.The soluble scFv was purified by affinity chromatography, and its relative molecular mass was determined by Western blot.The ELISA assay was used to identify the immunocompetence of the antibody.Immunocytochemical staining and radioimmunoimaging were employed to determine the affinities of scFv binding with CCR7 in cell line and in nude mice.Results The insert ratio of ScFv gene was 90%(18/20), enzyme digest reaction showed the aim products on 1% agarose gel.ScFvs were obviously enriched after 7 round panning.Western blot result showed soluble scFv's molecular mass was about 34 KD.ELISA analysis showed dissolved antibody had high immunocompetence to MDA-MB-435 s cells.Immunocytochemical staining and radioimmunoimaging indicated that ScFvs were bound efficiently to MDA-MB-435 s cells which expressed CCR7.Conclusions ScFvs against CCR7 are successfully acquired by screening the phage antibody library.The soluble ScFvs have high affinity and specifical binding to human breast cancer cells.

Construction of human naive phage antibody library and primary screening of the gab antibodies against gp96 / 中国综合临床

Objective To construct a naive human Fab fragment phage display library,from which the anti-gp96 antibodies may be panned by the gp96 purified from the tissue of urothelial carcinoma in the urinary bladder and provide a basis to new therapy for the malignant tumors.Methods Peripheral blood lymphocytes were isolated from 800 ml of blood,which was obtained from four healthy blood donors.The heavy chain Fd and light chain cDNA synthesized from the total RNA of lympbocytes were amplified by PCR with variable regions 5' and 3' primers of heavy and light chain, and the amplification products were ligated into the phagemid vector pComb3, then the ligated sample was transformed into competent E.coli XL1-Blue by electroperation.The transformed cells were infected with VCSM13 helper phage to yield recombinant phage antibody Fabs.The phagemids abstracted from amplified E.coli were cut with endonucleases such as Sac Ⅰ,Xba Ⅰ,Xho Ⅰ and Spe Ⅰ, and both the phage antibody Fabs and phage-raids abstracted from amplified E.coil were amplified by PCR to monitor the insertion of the genes of light chain or heavy chain Fd fragment.The gp96 purified from the urothelial carcinoma tissue of the bladder by affinity chromatog-raphy on eoncanavalin-A sephnrose and DEAE-sephnrose ion exchange chromatography were utilized as antigens to process three rounds of panning to the original Fab antibody library.Results The quantity of total RNA and cDNA were qualified.By combination of light chain and heavy chain genes, an antibody library containing 6.6×106 clones was obtained, and both the cutting of enzymes and PCR showed that there were the genes of light chain or heavy chain Fd fragment in the phagemids.The gp96 protein was obtained from urothelial carcinoma tissue in the urinary bladder.After having been panned by gp96, the original antibody library gained enrichment by 68 times.Conclusion Utilizing the technology of phage surface display, specific antibody can be gained from the human naive Fab phage display library,which can be used for immunological therapy for tumors.

Selection and preliminary identification of human Fab fragement antibody against amylin from phage antibody library / 中国免疫学杂志

Objective:To obtain antibodies against amylin from a 'naive' human Fab fragment antibody phage diasplay library and to analyze the specificity of antigen binding activity.Methods:Panning and screening Fab antibody from the antibody library,the positive clones with well reactivity to amylin were selected after five times selection of 'adsorption-elution-enrichment'.Then the plasmid DNA which was extracted from the clones,was digested with Spe Ⅰ and Nhe Ⅰ to delete gⅢ (about 660 bp).The digested 47 000 bp DNA which was purified after separation of bands from agarose gel was ligated with T4-DNA ligase.The constructed expressing phagemids were transformed to the BL21(DE3)pLysS,soluble Fab was expressed in it by the induction of IPTG and its characteristics and specificity were determined by ELISA and Western blot.Results:Soluble Fab antibodies were expressed in E.coli.According with molecular weight of IgG Fab,protein band of about 47 kD was shown by SDS-PAGE.Western blot using the goat anti human IgG-HRP showed their binding activities.ELISA showed their specificity with amylin antigens and they did not react with bovine serum albumin.Conclusion:The high level expression and identification of the soluble human anti- amylin Fab fragment antibodies has been obtained successfully,which lays a solid foundation for further researching about the biological and pathological activities of amylin.

Construction of gene library of human-originated single-chain variable fragment antibody associated with lung adenocarcinoma / 重庆医科大学学报

Objective:To construct human single-chain variable fragment (scFv) antibodies gene library associated with lung adenocarcinoma. Methods:Total RNA was extracted from the lymphatic tissue near the lung adenocarcinoma.VH and VL fragments were amplified with RT-PCR,the purified VH and VL fragments were used to produce scFv fragment by splicing-overlap-extension PCR. The scFv gene was cloned in pCANTAB-5E Phasmid,then transferred to Ecoli TG1.The insertion ratio of antibody gene was identified with RT-PCR,the positive enzyme-cutting products were identified with 1.5% agarose gel electrophoresis. Results:Clear 28 S and 18 S strips were found in total RNA;The size of VH is about 370 bp,VL is about 350 bp.The size of scFv is about 750 bp.After transformation into Ecoli TG1,2.2?107 CFU/?g ampicillin resistant bacteria colonies grow after overnight culture,and the positive insert ratio was 83.3%. Conclusion:Human single-chain variable fragment(scFv) antibodies gene associated with lung adenocarcinoma was constructed successfully. It could provide bases to further screen the antibody library construction.

Preparation and Identification of Anti-lactoferrin Single Chain Fv Antibody / 医学研究杂志

Objective To prepare a specific anti-lactoferrin single chain variable fragment(ScFv).Methods Anti-lactoferrin clones were screened from a 'naive' phage antibody library against the immobilized lactoferrin antigen,then the clones were transformed to the E.coli HB2151 to give soluble expression of antibody fragments.The culture supernatant containing ScFv was purified by immobilized metal affinity chromatography,and then determined with SDS-PAGE and ELISA.Results The results demonstrated that ScFvs were specific;they did not react with transferrin,lysozyme and bovine serum albumin in ELISA.The SDS-PAGE showed that the ScFvs had high purity through affinity chromatography and the molecular weight of them was about 32 kD.Conclusions The successful generation of the ScFvs against lactoferrin provides a basis for further study and clinical applications for dry eye and other ocular diseases.

The Construction and Expression of Phage Display scFv Library from the Spleen Cells of Mice Immunized With B3HM Cells / 中国生物工程杂志

To construct a scFv library by phage display technique from the spleen cells of mice immunized with B3HM cells. Three mice were immunized with B3HM cells, and their spleen cells were harvested. The genes of VH and Vk were amplified by RT-PCR from the cDNA of the immunized spleen cells and a scFv-phage display antibody library was constructed. The capacity of library was measured,and the variety of the library was analyzed by digesting with restriction endonuclease BstNI.ScFv phage clones were randomly picked and identified phage-scFv clone by binding B3HM cells using immunofluorescein.A scFv library containing 5?106 individual clones which showed different patterns after digested with restriction endonuclease BstNI was produced. Individnal phage-scFv clone showed B3HM cells positive using immunofluorescein. A scFv library of anti-B3HM cell surface molecules has been constructed. It will be useful for finding out some novel genes of causing leukemia, and establishs the infarctate foundation of clarifying the pathogenesis of leukemiagenesis.

Application of two bacteria colony-PCR methods in the screening of phage antibody library / 医学研究生学报

Objective:To value the application of two bacteria colony-PCR methods in the screening of phage antibody library. Methods:Five positive monoclonal bacterium were respectively suspended in either deionized water or 0.1% Triton X-100, and then boiled to be used as template in PCR. . The DNAs products of PCR were extracted and digested by two enzymes, and then determined by electrophoresis. Results:The inserted genes were detected in all the 5 clones after PCR and enzyme digestion .Conclusion:Bacteria colony-PCR can be used in screening positive recombinant colonies. The bacteria colony-PCR method with bacteria colonies suspended in deionized water is valuable in large scale positive recombinant bacterium screening.

Screening and identification of phage antibodies against human lipopolysaccharide binding protein / 第三军医大学学报

Objective To obtain and identify monoclonal antibody against human lipopolysaccharide binding protein (LBP). Methods Three clones of antibody with better activity against human LBP were isolated after human antibody library screening by human LBP and 5 rounds of enrichment. After plasmid extracting, geneⅢ cutting, self-recircling and electric transforming, soluble Fab was expressed in E.coli. XL1-blue by the induction of IPTG and its characteristics were determined. Results The positive antibody was concentrated to 8.16?104 folds and the highest activity of the three clones was 106 . Conclusion Phage antibody against human LBP has been obtained successfully, which lays a solid foundation for researching its function.

Generation of antiidiotypic antibody to monoclonal antibody MGd1 directed against gastric carcinoma by phage antibody library technique / 第三军医大学学报

Objective To pave the way for developing recombinant antiidiotypic antibody(antiId)vaccine of gastric carcinoma by generating phagedisplayed antiId to monoclonal antibody MGd1 directed against the cancer. Methods Balb/c mice were immunized i.p. with MGd1 conjugated with KLH, and mRNA was isolated from the spleens of the immunized mice. VH and VL DNAs of the antibody were amplified separately by RTPCR and assembled into ScFv DNAs with a linker DNA by PCR. The ScFv DNAs were ligated into the phagemid vector pCANTAB5E and the ligated sample was transformed into competent E.coli TG1. The transformed cells were infected with M13KO7 helper phage to yield phage antibody ScFv library. After four rounds of panning to the library with MGd1, the MGd1positive clones were selected by ELISA from the enriched phages. The types of the antiId ScFv displayed on the selected phage clones were preliminary identified by competition ELISA. Results The VH,VL and ScFv DNAs were about 340 bp, 320 bp and 750 bp respectively. After four rounds of panning to the antibody library, 17 MGd1positive phage clones displayed antiId ScFv were selected from 40 enriched phage clones, among which 3 displayed ? or ? type antiId ScFv. Conclusion The successful generation of antiId ScFv to monoclonal antibody MGd1 by recombinant phage antibody library technology might lay a foundation for screening of novel candidate molecules for developing recombinant antiId vaccine of gastric carcinoma.

Screening and identification of human anti-HIF-1? scFv of lung adenocarcinoma / 第三军医大学学报

Objective To screen human anti-hypoxia-inducible factor (HIF)-1? scFv of lung adenocarcinoma from large phage antibody library and identify the positive clones. Methods Panning of large phage antibody library against lung adenocarcinoma cell line A549 and HIF-1? was conducted respectively to select specific antibodies. E. coli HB2151 was infected to induce the expression of soluble scFv. The binding activity and specificity were tested by ELISA and immunocytochemical assay. The expression and relative molecular weight of the soluble scFv was detected by SDS-PAGE and Western blot analysis. Results After panning,the target scFv was enriched,and ELISA results showed that positive reactions to HIF-1? were detected in 5 of 10 random clones with a positive ratio of 50%. Immunocytochemical analysis showed the specific affinity of the antibodies to A549 cells. The soluble human anti-HIF-1? scFv fragments of lung adenocarcinoma were expressed in E. coli HB2151 and then confirmed by SDS-PAGE. The result of Western blotting showed that the relative molecular weight of the soluble scFv was about 30?103. The binding activity and specificity were confirmed by ELISA. Conclusion Human anti-HIF-1? scFv of lung adenocarcinoma is successfully obtained with large phage antibody library technique.

Construction of and screening for phage antibody library of human lung adenocarcinoma / 第三军医大学学报

Objective To construct human single-chain antibody gene library associated with lung adenocarcinoma, and screen lung adenocarcinoma cell A549-specific antibody. Methods The lymphatic tissue near lung adenocarcinoma was used to construct human single-chain antibody gene library. The specific antibody to lung adenocarcinoma cell A549 was screened from the antibody library. Positive clone bacteria were transformed to E. coli HB2151, and their dissolvability was observed. The soluble scFv was purified by affinity chromatography and its relative molecular mass was determined by SDS-PAGE and Western blotting. The specificity of scFv to human lung adenocarcinoma cells was identified with ELISA. Results The phage antibody library of 4.6?107 was constructed successfully. Single-chain antibody of human lung adenocarcinoma was enriched. The ratio of yield was increased gradually, 181 times higher after 5 rounds of panning than after the first round of panning. SDS-PAGE and Western blotting results showed soluble scFv' molecular mass was about 30 000. ELISA showed dissolved antibody had high specificity to bind A549 cells, not MDA-MB-435. Conclusion The single-chain antibody gene library of human lung adenocarcinoma was constructed successfully, and specific antibodies to lung adenocarcinoma were screened, providing the basis for single-chain antibody radionuclide imaging and treatment.

Screening of anti-idiotypic antibody to monoclonal antibody MC3 directed against colorectal carcinoma by phage antibody library technology / 中国免疫学杂志

Objective:To generate phage displayed anti idiotypic antibody single chain variable fragments(anti Id ScFv)to monoclonal antibody MC3 directed against colorectal carcinoma.Methods:Balb/c mice were immunized i.p. with MC3(McAb against colorectal Carcinoma) conjugated with KLH,and mRNA was isolated from the spleens of the immunized mice.VH and VL DNAs of the antibody were amplified separately and assembled into ScFv DNAs with a linker DNA by PCR.The ScFv DNAs were ligated into the phagemid vector pCANTAB5E and the ligated sample was transformed into competent E.coli TG1.The transformed cells were infected with M13KO7 helper phage to yield phage antibody ScFv library.After four rounds of panning to the library with MC3,the MC3 positive clones were selected by ELISA from the preselected phages.Results:The VH,VL and ScFv DNAs were about 340,320 and 750 bp respectively.After four rounds of panning to the antibody library,15 MC3 positive phage clones displayed anti Id ScFv were selected from 50 enriched phage clones.Conclusion:The phage displayed anti Id ScFv to MC3 were successfully selected by phage antibody library technology,which might provide new putative candidate molecules for developing recombinant anti Id vaccine of colorectal carcinoma.