AIM:To identify the scFv antibody fragments specific for hepatocellular carcinoma by biopanning from a large human naive scFv phage display library. METHODS: A large human naive scFv phage library was used to search f...AIM:To identify the scFv antibody fragments specific for hepatocellular carcinoma by biopanning from a large human naive scFv phage display library. METHODS: A large human naive scFv phage library was used to search for the specific targets by biopanning with the hepatocellular carcinoma cell line HepG2 for the positive-selecting and the normal liver cell line L02 for the counter-selecting. After three rounds of biopanning, individual scFv phages binding selectively to HepG2 cells were picked out. PCR was carried out for identification of the clones containing scFv gene sequence. The specific scFv phages were selected by ELISA and flow cytometry. DMA sequences of positive clones were analyzed by using Applied Biosystem Automated DNA sequencers 3 730. The expression proteins of the specific scFv antibody fragments in F.coli HB2151 were purified by the affinity chromatography and detected by SDS-PAGE, Western blot and ELISA. The biological effect of the soluble antibody fragments on the HepG2 cells was investigated by observing the cell proliferation. RESULTS: Two different positive clones were obtained and the functional variable sequences were identified. Their DNA sequences of the scFv antibody fragments were submitted to GenBank (accession nos: AY686498 and AY686499). The soluble scFv antibody fragments were successfully expressed in E.coli HB2151. The relative molecular mass of the expression products was about 36 ku, according to its predicted M, value. The two soluble scFv antibody fragments also had specific binding activity and obvious growth inhibition properties to HepG2 cells. CONCLUSION: The phage library biopanning permits identification of specific antibody fragments for hepatocellular carcinoma and affords experiment evidence for its immunotherapy study.展开更多
To construct ScFv and Fab from murine anti gastric cancer monoclonal antibody(mAb)3H11. Methods.At first,3H11 ScFv and Fab were constructed with V genes PCR amplified by degenerate primers for FR1.The bacterial expres...To construct ScFv and Fab from murine anti gastric cancer monoclonal antibody(mAb)3H11. Methods.At first,3H11 ScFv and Fab were constructed with V genes PCR amplified by degenerate primers for FR1.The bacterial expressed 3H11 Ab fragments showed no antigen binding activity.Then,phage antibody library and random mutated library were constructed from 3H11 hybridoma cells and panning selection was performed.Again the identification of positive clone was failed.Finally the N terminal sequences of V regions were resumed to 3H11 original sequences by site directed mutagenesis via PCR. Results.Binding activity to gastric cancer cells was detected only from N terminal sequence corrected 3H11 ScFv and Fab,though the expression of the Ab fragments was not affected.Correction of either VL or VH N terminal sequences could partially resume the antigen binding activity. Conclusion.Sequence changes of V region N terminal introduced by PCR may seriously affect antigen binding without affecting the expression of antibody.展开更多
Zinc transporter 8 （ZnT8） is a major autoantigen and a predictive marker in type 1 diabetes （T1D）. To investigate ZnT8-specific antibodies, a phage display library from TID was constructed and single-chain antibod...Zinc transporter 8 （ZnT8） is a major autoantigen and a predictive marker in type 1 diabetes （T1D）. To investigate ZnT8-specific antibodies, a phage display library from TID was constructed and single-chain antibodies against ZnT8 were screened and identified. Human T1D single-chain variable fragment （scFv） phage display library consists of approximately 1 ~ l0s clones. After four rounds of bio-panning, seven unique clones were positive by phage ELISA. Among them, C27 and C22, which demonstrated the highest affinity to ZnT8, were expressed in Escherichia coli Topl0F＇ and then purified by affin- ity chromatography. C27 and C22 specifically bound ZnT8 N/C fusion protein and ZnT8 C terminal dimer with one Arg325Trp mutation. The specificity to human islet cells of these scFvs were further confirmed by immunohistochemistry. In conclusion, we have successfully constructed a T1D phage display antibody library and identified two ZnT8-specific scFv clones, C27 and C22. These ZnT8-specific scFvs are potential agents in immunodiagnostic and immunotherapy of T1D.展开更多
基金Supported by the Major State Basic Research Development Program of China, 973 Program, No. 2002CB513100
文摘AIM:To identify the scFv antibody fragments specific for hepatocellular carcinoma by biopanning from a large human naive scFv phage display library. METHODS: A large human naive scFv phage library was used to search for the specific targets by biopanning with the hepatocellular carcinoma cell line HepG2 for the positive-selecting and the normal liver cell line L02 for the counter-selecting. After three rounds of biopanning, individual scFv phages binding selectively to HepG2 cells were picked out. PCR was carried out for identification of the clones containing scFv gene sequence. The specific scFv phages were selected by ELISA and flow cytometry. DMA sequences of positive clones were analyzed by using Applied Biosystem Automated DNA sequencers 3 730. The expression proteins of the specific scFv antibody fragments in F.coli HB2151 were purified by the affinity chromatography and detected by SDS-PAGE, Western blot and ELISA. The biological effect of the soluble antibody fragments on the HepG2 cells was investigated by observing the cell proliferation. RESULTS: Two different positive clones were obtained and the functional variable sequences were identified. Their DNA sequences of the scFv antibody fragments were submitted to GenBank (accession nos: AY686498 and AY686499). The soluble scFv antibody fragments were successfully expressed in E.coli HB2151. The relative molecular mass of the expression products was about 36 ku, according to its predicted M, value. The two soluble scFv antibody fragments also had specific binding activity and obvious growth inhibition properties to HepG2 cells. CONCLUSION: The phage library biopanning permits identification of specific antibody fragments for hepatocellular carcinoma and affords experiment evidence for its immunotherapy study.
文摘To construct ScFv and Fab from murine anti gastric cancer monoclonal antibody(mAb)3H11. Methods.At first,3H11 ScFv and Fab were constructed with V genes PCR amplified by degenerate primers for FR1.The bacterial expressed 3H11 Ab fragments showed no antigen binding activity.Then,phage antibody library and random mutated library were constructed from 3H11 hybridoma cells and panning selection was performed.Again the identification of positive clone was failed.Finally the N terminal sequences of V regions were resumed to 3H11 original sequences by site directed mutagenesis via PCR. Results.Binding activity to gastric cancer cells was detected only from N terminal sequence corrected 3H11 ScFv and Fab,though the expression of the Ab fragments was not affected.Correction of either VL or VH N terminal sequences could partially resume the antigen binding activity. Conclusion.Sequence changes of V region N terminal introduced by PCR may seriously affect antigen binding without affecting the expression of antibody.
基金supported by National Natural Science Foundation of China (81070622, 81370939)Provincial Six Talent Foundation of Jiangsu (2010-022)+1 种基金Municipal Science and Technology Foundation of Nanjing (009010684)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD, JX10231801)
文摘Zinc transporter 8 （ZnT8） is a major autoantigen and a predictive marker in type 1 diabetes （T1D）. To investigate ZnT8-specific antibodies, a phage display library from TID was constructed and single-chain antibodies against ZnT8 were screened and identified. Human T1D single-chain variable fragment （scFv） phage display library consists of approximately 1 ~ l0s clones. After four rounds of bio-panning, seven unique clones were positive by phage ELISA. Among them, C27 and C22, which demonstrated the highest affinity to ZnT8, were expressed in Escherichia coli Topl0F＇ and then purified by affin- ity chromatography. C27 and C22 specifically bound ZnT8 N/C fusion protein and ZnT8 C terminal dimer with one Arg325Trp mutation. The specificity to human islet cells of these scFvs were further confirmed by immunohistochemistry. In conclusion, we have successfully constructed a T1D phage display antibody library and identified two ZnT8-specific scFv clones, C27 and C22. These ZnT8-specific scFvs are potential agents in immunodiagnostic and immunotherapy of T1D.
