Affinity transfer of nanobodies to a CDR3 only single-domain antibody fragment NBL42 / 国际生物医学工程杂志

Objective:To evaluate the potential of a previously identified CDR3 only single-domain antibodies (sdAbs) fragment, NBL42, as a general framework for affinity transfer.Methods:The H3 loops of VHH-A4(A4), VHH-H5(H5), cAb-Lys3(L3) and B6H12 which bind with alliinase, PD-1, lysozyme and CD47, respectively, were grafted into the corresponding loop of NBL42. The genes of the reconstituted CDR3 only sdAbs were synthesized, expressed in E. coliand purified with Ni 2+ column affinity chromatography. The antigen binding and stability of the recombinant CDR3 only sdAbs were assayed by ELISA. Results:The recombinant NBL42-A4CDR3, NBL42-H5CDR3, NBL42-L3CDR3 and NBL42-B6H12CDR3 ran as a single peak at 15, 15, 28 and 16 kDa, respectively, in SDS-PAGE as expected molecular weight. Grafted sdAbs NBL42-A4CDR3 and NBL42-H5CDR3 expressed in a soluble form and specifically bind with alliinase and PD-1, respectively, but lost about 50% of their binding activity. In contrast, the grafted sdAbs NBL42-Lys3CDR3 and NBL42-B6H12CDR3 completely lost their antigen binding capacity. NBL42 sdAbs and grafted sdAbs NBL42-A4CDR3 and NBL42-H5CDR3 retain roughly half of their binding activity after 90 ℃ heat treatment, indicating high stability. The C88Y mutation in NBL42 and the Swiss Mode 3D model predicted that the C88Y residue in FR3 may play a key role in NBL42 stability and CDR3 affinity transfer.Conclusions:The structure of NBL42 has potential as a framework for CDR3 transplantation and affinity transfer.

Biosensors: Types, features, and application in biomedicine

Fast and precise diagnostic techniques are required for the treatment of many disorders. Biosensors are one of the diagnostic devices that are applicable in biological and medical sciences. Biosensors could be utilized to recognize biological molecules with high sensitivity. Biosensors are consisted of different components and have different types. Each type of biosensor is used in a particular field according to its specific features. Nanobodies are a novel class of antibodies with small size, high affinity, and specificity to their target. The unique properties of nanobodies make them appropriate tools for diagnostic applications. In this paper, we review biosensors, and their features and roles in medicine. Antibody/nanobody-based biosensors are also specifically discussed.

Method of preparing macrophage-targeting nanobody 68Ga-NOTA-Nb119 as PET molecular probe / 西安交通大学学报(医学版)

【Objective】 To prepare positron emission computed tomography (PET) molecular probes targeting macrophages using Nb119 and BCⅡ10 labeled with 68Ga nuclide. 【Methods】 To explore the labeling conditions of nanobodies with 68Ga nuclides, first, the anti-Vsig4 nanobody Nb119 and isotype control antibody BCⅡ10 were incubated with NOTA and then purified to obtain the chelating agent-modified NOTA-Nb119 and NOTA-BCⅡ10. The NOTA-Nb119 and NOTA-BCⅡ10 were further incubated with 68Ga. Finally, NOTA-Nb119 was identified by SDS-PAGE and MALDI-TOF methods, and the radiochemical purity was detected by radio-HPLC. 【Results】 The results of SDS-PAGE showed that the lanes of the successfully labeled NOTA-Nb119 had apparent hysteresis than the unlabeled nanobody band, which proved that the molecular weight of the labeled product was increased and NOTA successfully modified the nanobody. Subsequently, 68Ga nuclides could successfully label Nb119 and BCⅡ10. According to radio-HPLC detection, the radiochemical purity of NOTA-Nb119 and NOTA-BCⅡ10 labeled with 68Ga was greater than 90% and remained stable. 【Conclusion】 68Ga-labeled nanobodies have high radiochemical purity and high stability, indicating that this study can be applied to other nanobodies for modification and labeling and provides a practical and feasible method for the preparation of PET using nanobodies.

Development of novel-nanobody-based lateral-flow immunochromatographic strip test for rapid detection of recombinant human interferon α2b / 药物分析学报

Recombinant human interferon α2b(rhIFNα2b)is widely used as an antiviral therapy agent for the treatment of hepatitis B and hepatitis C.The current identification test for rhIFNα2b is complex.In this study,an anti-rhIFNα2b nanobody was discovered and used for the development of a rapid lateral flow strip for the identification of rhIFNα2b.RhIFNα2b was used to immunize an alpaca,which established a phage nanobody library.After five steps of enrichment,the nanobody I22,which specifically bound rhIFNα2b,was isolated and inserted into the prokaryotic expression vector pET28a.After subsequent purification,the physicochemical properties of the nanobody were determined.A semiquantitative detection and rapid identification assay of rhIFNα2b was developed using this novel nanobody.To develop a rapid test,the nanobody I22 was coupled with a colloidal gold to produce lateral-flow test strips.The developed rhIFNα2b detection assay had a limit of detection of 1 μg/mL.The isolation of I22 and successful construction of a lateral-flow immunochromatographic test strip demonstrated the feasibility of performing ligand-binding assays on a lateral-flow test strip using recombinant protein products.The principle of this novel assay is generally applicable for the rapid testing of other com-mercial products,with a great potential for routine use in detecting counterfeit recombinant protein products.

Preliminary Study on Screening and Identification of Lewis a Antigen Mimic Epitope in Alpaca Phage Display Nanobody Library / 中国实验血液学杂志

OBJECTIVE@#To establish a new method for synthesizing Lewis blood group antigens, that is, the mimotopes of Lewis blood group antigens were screened by using an alpaca phage display nanobody library.@*METHODS@#We selected mimotopes of the Lewis a (lea) antigen by affinity panning of an alpaca phage display nanobody library using a monoclonal anti-lea antibody. Enzyme-linked immunosorbent assay (ELISA) was used to test the affinity of the positive clones for the monoclonal anti-lea antibody, and the high-affinity positive clones were selected for sequencing and synthesis. Finally, the sensitivity, specificity and reactivity of the synthesized lea mimotope in clinical samples were verified by ELISA.@*RESULTS@#A total of 96 phage clones were randomly selected, and 24 were positive. Fourteen positive clones with the highest affinity were selected for sequencing. The result showed that there were 5 different sequences, among which 3 sequences with the highest frequency, largest difference and highest affinity were selected for expression and synthesis. The sensitivity and specificity of lea mimic antigen by ELISA showed that, the minimum detection limit of gel microcolumn assay (GMA) and ELISA method were 25 times different, and the lea mimic antigen had no cross reacted with the other five unrelated monoclonal antibodies(P<0.001). Finally, 30 clinical plasma samples were analyzed. The mean absorbance of the 15 positive plasma samples was significantly higher than that of the 15 negative plasma samples (P=0.02). However, the positive signal values of the clinical samples were much lower than those of the monoclonal antibodies.@*CONCLUSION@#A new method of screening lea mimic antigen by using alpaca phage nanoantibody library has been established, which is expected to realize the screening of lea mimotopes, thus realizing the application of high-sensitivity detection methods such as ELISA and chemiluminescence in blood group antibody identification.

Purification and activity of anti-PD-L1&CXCR4 bispecific nanobody / 中国药科大学学报

@#Targeted programmed death-ligand 1 (PD-L1) and CXC chemokine receptor type 4 (CXCR4), gene sequences encoding anti-PD-L1 nanobody and anti-CXCR4 nanobody were cloned into the pET-22b (+) vector to construct recombinant expression plasmid of anti-PD-L1&CXCR4 bispecific nanobody, which was connected with 6 × His tag and transformed into E.coli BL21 (DE3). The expressed proteins were then found to exist as a soluble form in the supernatant of bacterial lysate after induction of IPTG.Three purification methods were used to obtain the target protein in order to improve the yield and purity of the bispecific nanobody.The bacterial supernatant was separated and purified by His Trap FF affinity chromatographic column.The target protein output could exceed 1 mg/L, and the product purity could reach up to 97%.Besides, the anti-PD-L1&CXCR4 bispecific nanobody shows a specific binding ability to two antigens on the cell surface, enhancing the cytotoxicity of IL-2 activated human peripheral blood mononuclear cells (PBMC) to tumor cell line AsPC-1, which lays the foundation for further evaluation of its drug efficacy in vivo.

Anti-FGF-2 nanobody inhibits rat corneal angiogenesis induced by alkali burn / 中国临床药理学与治疗学

AIM: To investigate the possible use of anti-FGF-2 nanobody for the treatment of pathological neovascularization. METHODS: SD rats were divided into a sham operation group, a control group (3 mm diameter circular filter paper soaked with 1 mol/L NaOH solution was applied to the central part of the cornea of rats for 30 s to prepare the rat model of alkali-burn angiogenesis) and a treatment group (treated with a drop of 3 mg/mL anti-FGF-2 nanobody 7 days after the operation. Repeat application 3x/day for 14 days). Corneal angiogenesis was measured by stereoscopic microscopy and CD31 immunohistochemical staining. The mRNA and protein expression levels of VEGF and FGF-2 were detected by quantitative fluorescence PCR (qPCR), enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry.RESULTS: (1) Blood vessel: The area of the treatment group was significantly reduced compared with the model group, and the vascular lumen was narrower (P0.05); (3) Expression levels of VEGF mRNA and protein: The treatment group was significantly higher than the model group (P<0.05). In addition, the expression of VEGF also increased significantly in the continuous administration of the sham operation group. CONCLUSION: Anti-FGF-2 nanobody can be used for the treatment of angiogenesis. However, the expressions of VEGF will compensatorily increase after blocking FGF-2 in normal or pathological rats.

The screening and identification of internalized nanobody against EpCAM / 药学学报

Epithelial cell adhesion molecule (EpCAM) is a popular target for cancer therapy. In this research, 3 nanobodies with high specificity and endocytosis activity against EpCAM were developed, which provides a basis for the study of immunotoxin based on EpCAM. In our preliminary experiments, we have immunized a camel with EpCAM-Fc antigen and constructed a high-quality phage display library. Seventeen nanobodies with different complementarity determining region (CDR) 3 sequences have been screened after 3 rounds of biopanning by phage display technology. The animal procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of Fudan University School of Pharmacy. After purification, 7 nanobodies showed high cell binding activity by fluorescent activated cell sorting (FACS) identification. Furthermore, 3 nanobodies presented high endocytosis activity based on FACS and laser confocal microscopy, which also showed high affinity to EpCAM measured by ForteBio. According to this study, we aimed to provide a novel alternative approach to the EpCAM-targeted therapy and to provide guidance for the study of nanobody based immunotoxins for other targets.

Construction and quality analysis of phage display library for random mutagenesis of camel nanobody / 国际生物医学工程杂志

Objective To construct phage display antibody library of artificial mutation to compare with the sequence of the natural phage display antibody library. To scientifically evaluate the quality of the artificial mutation of phage display library, and provide some references for the further transformation of the nanobody. Methods Using random mutation method, NNY fixed-point santuration mutation was performed on combine the follicle-stimulating hormone receptor (FSHR) of human nanobody. The mutant DNA sequence was connected to the vector pMECS to construct the phage display library of VHH06-CDR3 random mutation. By sequencing and analysis of DNA sequences, the diversity of the library and the amino acid distribution of CDR3 were compared between mutation library and the immune library of FSHR. The degree of enrichment of cloning was determined by six rounds of affinity screening. Results According to the NNY mutation rule ,the CDR3 regions with 16 amino acids by random mutations was synthesized and the VHH-CDR3 random mutant phage display library was constructed . The phage display library of VHH06-CDR3 random mutant size was 7.36×108 cfu/ml. Polyclonal and monoclonal phage ELISA showed that after six rounds of screening, the output phage and the combination of FSHR showed obvious enrichment, but there was no clone combined with FSHR. Conclusions Although the VHH06-CDR3 mutant phage display library has sequence diversity, it is not conducive to obtaining target antibodies in affinity screening due to the lack of functional diversity of CDR3.

Enhance the affinity of nanobodies to CD47 antigen by fusion expression of COMP48 self-folding peptide / 国际生物医学工程杂志

Objective To modify CD47 nanobody with the self-folding peptide human cartilage oligomeric matrix protein (COMP48) so as to enhance its affinity to CD47 antigen. Methods The fusion sequences of COMP48 and CD47 nanobody (VHHB1) were designed and synthesized, and the recombinant plasmid pET22b-VHHB1-COMP48 was constructed and transformed into E. coli BL21 (DE3) to induce expression of the fusion protein. The binding specificity and affinity of the fusion protein and the antigen CD47 were detected by Western Blot, indirect enzyme-linked immunosorbent assay (ELISA) and non-competitive ELISA. Results The recombinant VHHB1-COMP48 was expressed in BL21(DE3) by inducing with 1 mmol/L IPTG and purified at 90％homogenous in IMAC. Western Blot results showed that the recombinant protein VHHB1-COMP48 specifically binds to antigen CD47 but not to unrelated protein. The indirect ELISA and non-competitive ELISA results showed that the affinity of the conjugated recombinant protein VHHB1-COMP48 was enhanced compared to that of the non-conjugated nanobody, and the difference was statistically significant ( P<0 . 01 ) . Through non-competitive ELISA , the constants of affinity and dissociation constants were 6.97 ×107 L/mol and 1.434 ×10-8 mol/L, respectively. Conclusions The affinity of the nanobody for the antigen can be improved by conjugating a human cartilage matrix protein (COMP48) after the nanobody.

Construction and screening of phage display library for TIM-3 nanobody / 药学学报

Immunotherapy is a new strategy for cancer treatment that has the potential to treat all types of cancer. T cell immunoglobulin and mucin-domain-containing molecule-3 (TIM-3) is a key negative regulator of T cell activation. TIM-3 blockage using anti-TIM-3 monoclonal antibody therapy has a great appeal and special advantages. Nanobodies, derived from heavy chain fragment in camelid animals, are now proving clinical values in the development of antibody drugs. In this study, we have immunized camel with TIM-3 antigens and then constructed phage display library. Moreover, 29 nanobodies with different complementarity-determining regions sequences have been screened from the phage display library by phage display technology. In addition, we successfully constructed the cell line stably expressing TIM-3, and screened 10 TIM-3 nanobodies with high specificity and high affinity using flow cytometry. Our study will lay the foundation for the future screening and development of anti-TIM-3 whole humanized functional nanobody.

Single-domain antibody - advances in research and application / 生物工程学报

Conventional IgG is composed of heavy and light chains. The light chain has one variable region (VL) and one constant region (CL) domain, whereas the heavy chain has one variable region (VH) and three constant region domains (CH1, CH2 and CH3). Single domain antibody (sdAb) is a kind of antibody that is composed of a variable domain of heavy chain and devoid of the light chain completely. Due to its small size, it is also called as nanobody. Although the sdAb has a simple structure, it can exhibit a comparable even better antigen-binding affinity than conventional antibody. Compared with conventional antibody, the small size, high stability and simplicity in recombinant expression are representative advantages of sdAb. In recent years, scientists are becoming increasingly interested in the roles of sdAb in fundamental biomedical research and clinical application. In this review, we summarized the structural features, physicochemical properties, screening strategies and recent advances in application of sdAb.

Heterologous Expression of Nanobodies: a Recent Progress / 中国生物工程杂志

Heavy chain antibodies (HcAb) without light chains are naturally produced by camelids.The single domain antigen-binding fragment of HcAb is referred to as VHH or nanobody (Nb),which is the smallest antigen-binding entity at present.Several characteristics such as low molecular weight,high stability,and low immunogenicity make the use of nanobodies superior to the conventional antibodies.Currently,nanobodies are highly valuable antibodies for various applications,including fundamental research,diagnostics,and therapeutics.A variety of nanobodies are investigated in clinical researches.The recent progresses of heterologous expression of nanobodies in seven expression systems,including Gram-negative and positive bacteria,yeasts,filamentous fungi,insect cells,mammalian cells and plant cells were focused on,and the expression systems,hosts,characteristics of vectors,construction of vectors and yield of nanobodies were summarized.The strategies to increase the yield of nanobodies are discussed from molecular level,expression level and rational design.

Preparation of immunotoxin BI7D12-PE38KDEL directed to EGFR and determination of its activity in vitro / 中国免疫学杂志

Objective:To prepare nanobody-based immunotoxin BI7D12-PE38KDEL targeting EGFR and to examine its cytotoxicity against EGFR positive tumor cells.Methods:By using molecular cloning strategy,prokaryotic expression construct of pET28a-BI7D12-PE38KDEL was generated which consisted of nanobody 7D12 targeting EGFR in the form of a divalent fused with PE38KDEL,a truncated form of pseudomonas exotoxin A via a flexible peptide(G4S)4,and then transformed into E.coli BL21(DE3).Protein expression was induced by adding IPTG,purified by Ni-affinity column chromatography,and verified by Western blot.The binding capacity of the resulted immunotoxin to EGFR-positive cells A549,HT29,MCF-7 and EGFR-negative cells CEM,Jurkat were determined by flow cytometry assay,and its cytotoxicity against the target cells was examined.Briefly,tumor cells were treated with different dosage of the immunotoxin,and the killing efficacy of BI7D12-PE38KDEL on these cells were assessed by WST-1 assay after 72 hours.Results:The SDS-PAGE and Western blot results showed the recombinant immunotoxin BI7D12-PE38KDEL was successfully prepared,and majority of them was expressed in soluble form.BI7D12-PE38KDEL could selectively bind to EGFR-positive cells of A549,HT29,and MCF-7.More importantly,the immunotoxin exhibited much more significant killing effect on these EGFR positive cells compared to the negative control group of CEM and Jurkat cells(P<0.01).Conclusion:In the current study,the nanobody-based immunotoxin BI7D12-PE38KDEL targeting EGFR was successfully prepared and exhibited a superior inhibition effect for the growth of EGFR-positive cells.

Generation of an alpaca derived nanobody recognizing human Her2 antigen / 军事医学

Objective To obtain alpaca single domain antibody targeting Her2.Methods An alpaca was immunized with human recombination Her2 protein mixed with Freund's adjuvant.Total RNA was extracted from the alpaca's blood and was used to synthesize first strand cDNA.Single domain antibody variable region (VHH) gene of the alpaca was amplified by PCR and cloned into pMES4 vector for library construction.After screening, E.coli BL21 (DE3) was transformed with selected clones and was induced with IPTG for the expression of recombinant proteins.The nanobody was purified by nickel ion affinity chromatography column.The affinity of the nanobodies to Her2 was tested.Results After the second round of screening, two antibody clones were selected, H3 and H5.The affinity of H5 was 8.106×10-10mol/L.Histochemistry results showed that H5 could recognize Her2 antigen in breast tumor tissue.Conclusion An Her2 specific nanobody derived from alpaca is obtained through phage display library screening, which can recognize human Her2 antibody in human breast tumor tissue.

Engenharia de anticorpos na busca por fragmentos funcionais para insumos de diagnóstico e aplicações terapêuticas / Antibody engineering in the search for functional fragments for diagnostic inputs and therapeutic applications

Anticorpos, agentes empregados no desenvolvimento de pesquisas biomédicas, no diagnóstico e na terapêutica, possuem elevada capacidade de interação aos mais variados ligantes, Estruturalmente são heterotetrameros constituídos por duas cadeias leves e duas cadeias pesadas com massa molecular de aproximadamente 150 kDa, Visando melhorar as características farmacocinéticas e minimizar possíveis reações adversas desencadeadas por imunoglobulinas de origem não humana, a engenharia molecular de anticorpos vem obtendo fragmentos de anticorpos como porções Fab, F(ab?)2, scFv e Fv, Em adição aos anticorpos convencionais, camelídeos produzem imunoglobulinas funcionais desprovidas de cadeia leve, onde o domínio variável da cadeia pesada, denominado VHH ou nanocorpo, é responsável pelo reconhecimento antigênico, Apresentando características adequadas ao desenvolvimento de fármacos com alta capacidade de neutralização, fragmentos VHHs vêm sendo propostos para uso em imunoterapia passiva ou em drug-delivery, No diagnóstico esses fragmentos podem ser aplicados na construção de biosensores ou na imagiologia, atuando na detecção de células cancerígenas, no monitoramento de tumores ou em alterações celulares...

Antibodies, agents employed for the development of biomedical research, diagnostic and therapeutic, have high ability to interact with different ligands. Structurally are heterotetramers constituted by two light and two heavy chains, with molecular weight of approximately 150 kDa. Aiming to improve the pharmacokinetic properties and minimize possible adverse reactions triggered by immunoglobulins of non-human origin, the molecular engineering of antibodies has been obtaining fragments of antibodies, such as Fab, F(ab?)2, Fv and scFv. In addition to the conventional antibodies, camelids produce functional immunoglobulins devoid of light chain, in which the variable domain, named VHH or nanocorpo, is able to recognize the antigen. With appropriate characteristics for the development of drugs with high neutralizing capacity, VHH fragments have been proposed for use in passive immunotherapy or drug-delivery. To the diagnosis, these fragments can be used to construct biosensors, in the imagiology , acting in the detection of cancer cells, tumor monitoring or cell changes...