B-type natriuretic peptide 분석을 위한 항 BNP scFv 항체의 대장균 세포질 내에서의 기능적 발현

맹보희(Bo Hee Maeng),남동현(Dong Hyun Nam),김용환(Yong Hwan Kim) 한국생물공학회 2009 KSBB Journal Vol.24 No.6

심장이상증상의 상태에서 분비되는 심장혈관호르몬인 BNP의 혈중 농도측정은 심장기능부전환자의 진단에 유용하게 이용 되고 있다. 혈청 또는 혈장에서의 BNP 농도측정은 샌드위치형태의 면역학적 검정법을 이용할 수 있으며, 이때에 항 BNP 항체를 BNP 탐지 인자로 사용할 수 있다. 특히, 탐지 인자로의 사용을 위해서는 항원항체 반응부분을 링커로 연결하여 전체 항체에 비해서 경제적이며 효율 면에서도 뛰어난 scFv의 사용이 용이하다고 판단하였고, 이에 scFv의 취약점인 대장균에서의 불용성 형태의 발현을 최소화 시키고 기능적 발현을 극대화하여 심장질환 진단용 센서의 센서 칩 항체로 사용할 수 있도록 항 BNP scFv 항체의 발현을 대장균 세포질 내에서 유도 하였다. 대장균 세포질내에서의 scFv 제작을 위하여 항 BNP scFv 항체 유전자를 pColdⅣ 벡터와 pET22b (+)벡터에 각각 클로닝한 후 발현 하였으며, 그 결과 대량 생산의 장점이 있는 강력한 T7 promoter를 지닌 pET22b (+) 벡터를 이용하여 낮은 온도에서 단백질의 발현을 느리게 유도할 때 적절한 단백질 접힘 현상이 일어나 기능적인 scFv의 발현이 극대화됨을 확인하였다. 또한 IPTG의 투여에 있어서 그 농도가 높아지면 빠른 단백질 유전자의 전사를 도와 발현율이 증가하지만 과도한 농도의 IPTG 투여는 세포내의 독성을 일으켜 단백질의 생산을 저해할 수 있다는 결론에 도달하였으며, 연구를 통하여 개발한 항 BNP scFv 항체가 오직 BNP 항원과의 결합특이성을 가진다는 사실도 확인 가능 하였다. B-type natriuretic peptide is a neurohormone secreted in the cardiac ventricles. BNP levels are elevated in patients with ventricular dysfunction. Therefore, the concentration of BNP is important factor to reflect diagnosis and prognosis for cardiovascular disease. In this respect, anti-BNP scFv is an urgent requirement for early diagnosis in the field of biosensor. Herein, the genetic codes of anti-BNP scFv were chemically synthesized and cloned into both pET22b (+) and pColdⅣ vector, respectively. The recombinant scFv was successfully expressed as a functional form in cytoplasm of E. coli and detected through Western blot and ELISA. The highest level of functional expression of anti-BNP scFv was achieved using pET22b (+) vector at 15℃ by addition of 0.1 mM IPTG. Additionally, being exposed to both BNP and ANP, anti-BNP scFv specifically captured only BNP. Therefore, anti-BNP scFv expressed in this study will be applied to measure the concentration of BNP as a diagnostic recognition molecule.

대장균의 alkaline phosphatase가 융합된 anti-DR4 single-chain Fv (ScFv) 항체의 개발

한승희,김진규,Han, Seung Hee,Kim, Jin-Kyoo 한국미생물학회 2016 미생물학회지 Vol.52 No.1

항체의 특이적 결합을 분석하는 효소면역분석법은 항원의 탐지를 위해 주로 horseradish peroxidase (HRP) 또는 alkaline phosphatase (AP) 등의 효소를 사용한다. 이때 효소를 주로 화학적으로 항체에 결합시켜 사용하게 되는데 이 과정이 복잡하며 불규칙하게 일어나서 항체 및 효소의 기능을 감소시키게 된다. 또한 대부분의 효소면역분석법에서는 주로 일차 항체의 항원결합을 탐지하기위해 이차 항체를 사용하는데, 즉 이차 항체에 결합한 효소의 기질발색에 의해 일차 항체의 항원결합을 탐지하므로 이차 항체가 요구 되어질 뿐만 아니라 이차 항체의 일차 항체에 대한 반응을 위한 부가적인 배양시간이 필요하다. 더욱 더 중요한 것은 이차 항체만의 비특이적 항원 결합 역시 제거되어져야 한다. 본 연구에서는 대장균의 genomic DNA로부터 PCR을 통해 alkaline phosphatase 유전자(Sadeghi et al., 2008)를 증폭 분리한 다음 이를 TRAIL (tumor necrosis factor ${\alpha}$ related apoptosis induced ligand) receptor인 death receptor 4 (DR4)에 특이적으로 결합하는 hAY4 single-chain Fv (ScFv)에 융합시킨 재조합 ScFv-AP 형태로 대장균에서 발현시켜 정제하였다. 정제된 hAY4 ScFv-AP는 SDS-PAGE에서 단량체(monomer) 분자량인 73.8 kDa을 나타내었다. 그러나 size-exclusion chromatography(SEC)에서는 147.6 kDa을 나타내는 결과를 통해 hAY4 ScFv-AP는 AP의 자연적인 비공유결합에 의해 이량체(dimeric form)형성이 유도되어짐을 확인하였다. 또한 ELISA, Western blot 그리고 immunocytochemistry에서 이차 항체 없이 일차 항체 hAY4 ScFv에 직접 융합된 AP의 기질발색에 의해 ScFv 일차 항체의 특이적 항원결합을 나타내었다. 요약하면 hAY4 ScFv와 대장균의 alkaline phosphatase 유전자를 융합시켜 대장균에서 수용성 형태로 성공적으로 정제하였으며 정제된 ScFv-AP 융합단백질은 ELISA, Western blot 및 immunocytochemistry에서 항원결합력을 나타냈으며 또한 구매에 따른 고비용, 부가적인 배양시간 및 비특이적 결합에 의한 오류 등의 문제점을 갖는 이차 항체를 사용하지 않고 직접적인 항원결합력을 나타내었다. Enzyme immunoassay to analyze specific binding activity of antibody to antigen uses horseradish peroxidase (HRP) or alkaline phosphatase (AP). Chemical methods are usually used for coupling of these enzymes to antibody, which is complicated and random cross-linking process. As results, it causes decreases or loss of functional activity of either antibody or enzyme. In addition, most enzyme assays use secondary antibody to detect antigen binding activity of primary antibody. Enzymes coupled to secondary antibody provide a binding signal by substrate-based color development, suggesting secondary antibody is required in enzyme immunoassay. Additional incubation time for binding of secondary antibody should also be necessary. More importantly, non-specific binding activity caused by secondary antibody should also be eliminated. In this study, we cloned AP isolated from Escherichia coli (E. coli) chromosome by PCR and fused to) hAY4 single-chain variable domain fragment (ScFv) specific to death receptor (DR4) which is a receptor for tumor necrosis factor ${\alpha}$ related apoptosis induced ligand (TRAIL). hAY4 ScFv-AP expressed in E. coli showed 73.8 kDa as a monomer in SDS-PAGE. However, this fusion protein shown in size-exclusion chromatography (SEC) exhibited 147.6 kDa as a dimer confirming that natural dimerization of AP by non-covalent association induced ScFv-AP dimerization. In several immunoassay such as ELISA, Western blot and immunocytochemistry, it showed antigen binding activity by color development of substrates catalyzed by AP directly fused to primary hAY4 ScFv without secondary antibody. In summary, hAY4 ScFv-AP fusion protein was successfully purified as a soluble dimeric form in E. coli and showed antigen binding activity in several immunoassays without addition of secondary antibody which sometimes causes time-consuming, expensive and non-specific false binding.

Antibody reformatting vector system (AbVec): a platform for converting single-chain variable fragment format to other ones using shared restriction enzyme sites

김동호,박수빈,이상호 한국구조생물학회 2019 Biodesign Vol.7 No.1

Single-chain antibody variable fragment (scFv) is widely used at screening stage. However, the scFv format often proves tobe inefficient in downstream stages such as crystallization and in vivo applications. Conversion of a scFv format to otherones such as a fragment antigen binding (Fab), a scFv-fragment crystallizable region (scFv-Fc), a scFv-constant heavychain (scFv-CH) and an immunoglobulin (IgG) formats can be cumbersome due to different sets of restriction enzyme sitesin multiple vectors. To facilitate antibody format conversion in laboratory settings, we developed a cloning platform, called“AbVec”, with the common restriction enzyme sites across various forms of vectors. In the AbVec platform, a scFv cloneselected from phage display is modularized into VH and VL regions and transferred to vectors for Fab, scFv-Fc, scFv-CH and IgG production using the same restriction enzyme sites. Using scFv F9, specifically recognizing a pneumococcalsecreted peptide, we demonstrated the AbVec platform yielded the expression vectors within a week. Different formats ofthe antibodies were successfully expressed and purified homogenously, supporting the usefulness of the AbVec platform. The AbVec platform will facilitate otherwise time-consuming conversion process in laboratory settings.

Therapeutic Strategy for the Prevention of Pseudorabies Virus Infection in C57BL/6 Mice by 3D8 scFv with Intrinsic Nuclease Activity

Lee, Gunsup,Cho, SeungChan,Hoang, Phuong Mai,Kim, Dongjun,Lee, Yongjun,Kil, Eui-Joon,Byun, Sung-June,Lee, Taek-Kyun,Kim, Dae-Hyun,Kim, Sunghan,Lee, Sukchan Korean Society for Molecular and Cellular Biology 2015 Molecules and cells Vol.38 No.9

3D8 single chain variable fragment (scFv) is a recombinant monoclonal antibody with nuclease activity that was originally isolated from autoimmune-prone MRL mice. In a previous study, we analyzed the nuclease activity of 3D8 scFv and determined that a HeLa cell line expressing 3D8 scFv conferred resistance to herpes simplex virus type 1 (HSV-1) and pseudorabies virus (PRV). In this study, we demonstrate that 3D8 scFv could be delivered to target tissues and cells where it exerted a therapeutic effect against PRV. PRV was inoculated via intramuscular injection, and 3D8 scFv was injected intraperitoneally. The observed therapeutic effect of 3D8 scFv against PRV was also supported by results from quantitative reverse transcription polymerase chain reaction, southern hybridization, and immunohistochemical assays. Intraperitoneal injection of 5 and $10{\mu}g$ 3D8 scFv resulted in no detectable toxicity. The survival rate in C57BL/6 mice was 9% after intramuscular injection of 10 $LD_{50}$ PRV. In contrast, the 3D8 scFv-injected C57BL/6 mice showed survival rates of 57% ($5{\mu}g$) and 47% ($10{\mu}g$). The results indicate that 3D8 scFv could be utilized as an effective antiviral agent in several animal models.

Therapeutic Strategy for the Prevention of Pseudorabies Virus Infection in C57BL/6 Mice by 3D8 scFv with Intrinsic Nuclease Activity

이건섭,조승찬,Phuong Mai Hoang,김동준,이용준,길의준,변성준,김택균,김대현,김성한,이석찬 한국분자세포생물학회 2015 Molecules and cells Vol.38 No.9

3D8 single chain variable fragment (scFv) is a recombinant monoclonal antibody with nuclease activity that was originally isolated from autoimmune-prone MRL mice. In a previous study, we analyzed the nuclease activity of 3D8 scFv and determined that a HeLa cell line expressing 3D8 scFv conferred resistance to herpes simplex virus type 1 (HSV- 1) and pseudorabies virus (PRV). In this study, we demonstrate that 3D8 scFv could be delivered to target tissues and cells where it exerted a therapeutic effect against PRV. PRV was inoculated via intramuscular injection, and 3D8 scFv was injected intraperitoneally. The observed therapeutic effect of 3D8 scFv against PRV was also supported by results from quantitative reverse transcription polymerase chain reaction, southern hybridization, and immunohistochemical assays. Intraperitoneal injection of 5 and 10 μg 3D8 scFv resulted in no detectable toxicity. The survival rate in C57BL/6 mice was 9% after intramuscular injection of 10 LD50 PRV. In contrast, the 3D8 scFv-injected C57BL/6 mice showed survival rates of 57% (5 μg) and 47% (10 μg). The results indicate that 3D8 scFv could be utilized as an effective antiviral agent in several animal models.

Generation of 1E8 Single Chain Fv-Fc Construct Against Human CD59

Hong, Jeong-Won,Cho, Woon-Dong,Hong, Kwon-Pyo,Kim, So-Seul,Son, Seung-Myoung,Yun, Seok-Joong,Lee, Ho-Chang,Yoon, Sang-Soon,Song, Hyung-Geun The Korean Association of Immunobiologists 2012 Immune Network Vol.12 No.1

Background: Therapeutic approaches using monoclonal antibodies (mAbs) against complement regulatory proteins (CRPs:i.e.,CD46,CD55 and CD59) have been reported for adjuvant cancer therapy. In this study, we generated a recombinant 1E8 single-chain anti-CD59 antibody (scFv-Fc) and tested anti-cancer effect.by using complement dependent cytotoxicity (CDC). Methods: We isolated mRNA from 1E8 hybridoma cells and amplified the variable regions of the heavy chain (VH) and light chain (VL) genes using reversetranscriptase polymerase chain reaction (RT-PCR). Using a linker, the amplified sequences for the heavy and light chains were each connected to the sequence for a single polypeptide chain that was designed to be expressed. The VL and VH fragments were cloned into the pOptiVEC-TOPO vector that contained the human CH2-CH3 fragment. Then, 293T cells were transfected with the 1E8 single-chain Fv-Fc (scFv-Fc) constructs. CD59 expression was evaluated in the prostate cancer cell lines using flow cytometry. The enhancement of CDC effect by mouse 1E8 and 1E8 scFv-Fc were evaluated using a cytotoxicity assay. Results: The scFv-Fc constructs were expressed by the transfected 293T cells and secreted into the culture medium. The immunoreactivity of the secreted scFv-Fc construct was similar to that of the mouse 1E8 for CCRF-CEM cells. The molecular masses of 1E8 scFv-Fc were about 120 kDa and 55 kDa under reducing and non-reducing conditions, respectively. The DNA sequence of 1E8 scFv-Fc was obtained and presented. CD59 was highly expressed by the prostate cancer cell line. The recombinant 1E8 scFv-Fc mAb revealed significantly enhanced CDC effect similar with mouse 1E8 for prostate cancer cells. Conclusion: A 1E8 scFv-Fc construct for adjuvant cancer therapy was developed.

Generation of 1E8 Single Chain Fv-Fc Construct Against Human CD59

홍정원,윤상순,조원동,홍권표,김솟을,손승명,윤석중,이호창,송형근 대한면역학회 2012 Immune Network Vol.12 No.1

Background: Therapeutic approaches using monoclonal antibodies (mAbs) against complement regulatory proteins (CRPs:i.e.,CD46,CD55 and CD59) have been reported for adjuvant cancer therapy. In this study, we generated a recombinant 1E8 single-chain anti-CD59 antibody (scFv-Fc)and tested anti-cancer effect.by using complement dependent cytotoxicity (CDC). Methods: We isolated mRNA from 1E8 hybridoma cells and amplified the variable regions of the heavy chain (VH) and light chain (VL) genes using reversetranscriptase polymerase chain reaction (RT-PCR). Using a linker, the amplified sequences for the heavy and light chains were each connected to the sequence for a single polypeptide chain that was designed to be expressed. The VL and VH fragments were cloned into the pOptiVEC-TOPO vector that contained the human CH2-CH3 fragment. Then, 293T cells were transfected with the 1E8 single-chain Fv-Fc (scFv-Fc) constructs. CD59 expression was evaluated in the prostate cancer cell lines using flow cytometry. The enhancement of CDC effect by mouse 1E8 and 1E8 scFv-Fc were evaluated using a cytotoxicity assay. Results: The scFv-Fc constructs were expressed by the transfected 293T cells and secreted into the culture medium. The immunoreactivity of the secreted scFv-Fc construct was similar to that of the mouse 1E8 for CCRF-CEM cells. The molecular masses of 1E8 scFv-Fc were about 120 kDa and 55 kDa under reducing and non-reducing conditions, respectively. The DNA sequence of 1E8 scFv-Fc was obtained and presented. CD59was highly expressed by the prostate cancer cell line. The recombinant 1E8 scFv-Fc mAb revealed significantly enhanced CDC effect similar with mouse 1E8 for prostate cancer cells. Conclusion: A 1E8 scFv-Fc construct for adjuvant cancer therapy was developed.

Ribosome Display를 이용한 항체선별 방법의 확립

이명신,권명희,김경민,박선,신호준,김형일,Lee, Myung-Shin,Kwon, Myung-Hee,Hwang Kim, Kyongmin,Park, Sun,Shin, Ho-Joon,Kim, Hyung-Il 대한면역학회 2003 Immune Network Vol.3 No.3

Background: Phage display is the most widely used technique among display methods to produce monoclonal antibody fragment with a specific binding activity. Having a large library for efficient antibody display/selection is quite laborious process to have more than $10^9$ members of transformants. To overcome these limitations, several in vitro selection approaches have been reported. Ribosome display that links phenotypes, proteins, directly to genotype, mRNA, is one of the in vitro display methods. Ribosome display can reach the size of scFv library up to $10^{14}$ molecules and it can be further diversified during PCR steps. To select the high affinity scFv from one pot library, we established ribosome display technique by modifying the previously reported eukaryotic translation system. Methods: To establish the antibody selection system by ribosome display, we used 3D8, anti-DNA antibody. A 3D8 scFv was synthesized in vitro by an in vitro transcription-translation system. The translated 3D8 scFv and the encoding 3D8 mRNA are connected to the ribosome. These scFv-ribosome-mRNA complexes were selected by binding to their specific antigens. The eluted mRNAs from the complexes are reverse transcribed and re-amplified by PCR. To apply this system, antibody library from immunized mouse with terminal protein (TP)-peptide of hepatitis B virus DNA polymerase TP domain was also used. This TP-peptide encompasses the 57~80 amino acid residues of TP. These mRNA/ribosome/scFv complexes by our system were panned three times against TP-peptide. The enrichment of antibody from library was determined by radioimmunoassay. Results: We specifically selected 3D8, anti-DNA antibody, against ssDNA as a model system. The selected 3D8 RNAs sequences from translation complexes were recovered by RT-PCR. By applying this model system, we enriched TP-peptide-specific scFv pools through three cycles of panning from immunized library. Conclusion: We show that our translating ribosome complexes are well maintained and we can enrich the TP-specific scFv pools. This system can be applied to select specific antibody from an antibody library.

Cell-free synthesis of scFv with enhanced solubility and disulfide bond formation

민승의,김동명 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

In this study we attempted to express the scFv antibodies that had been engineered to penetrate into the cells and give signal through split GFP complementation. Conventional cell-based gene expression methods often fail to produce sufficient amount of scFv. In contrast, cell-free protein synthesis system provides a high accessibility to the translational mechanism, thereby providing optimal environments to increase the productivity and solubility of scFv. scFv productivity was enhanced by adding a ubiquitin sequence in front of the ORF of scFv sequence. To increase the solubility, we used molecular chaperon GroEL/ES-enriched extract. To form correct disulfide bonds, we have changed redox conditions of the cell extract and reaction mixture using GSSG/GSH and DsbC. We expect that the established conditions would be applied as a general strategy for producing active scFvs.

Cell-free synthesis of functional cell-penetrating scFv in a cell-free protein synthesis system derived from Escherichia coli

박유진,( Christy Catherine ),( Devi Kasi ),이경호,신승민,김용성,김동명 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

In this study we attempted to express the scFv antibodies that had been engineered to penetrate into the cells and give signal through split GFP complementation. Cell-free protein synthesis system provides a high accessibility to the translational mechanism, thereby providing optimal environments to increase the productivity and solubility of scFv. To assist the formation of correct disulfide bonds, we have changed redox conditions of the cell extract and reaction mixture using GSSG/GSH redox buffer. To increase the solubility, we used a cell extract enriched with DsbA, DsbC, FkpA and SurA. We also used the leader sequence ubiquitin,in front of the target scFv and achieved a high level expression of functional scFv antibodies. The functionality has confirmed by reading the fluorescence signal of transfected cells in a black plate assay.