Generation of human monoclonal antibody Fab fragment to Zika Virus by Phage Display Technology / 中华实验和临床病毒学杂志

Objective@#In this study, phage display technology was used to construct the human anti-Zika virus(ZIKV), phage antibody library and to obtain and express the monoclonal antibody. The aim was to master the preparation and expression of human phage antibody library screening method for highly specific antibodies.@*Methods@#The whole blood samples of Zika patients were collected and the lymphocytes were isolated. The RT-PCR method was used to amplify the antibody light chain and heavy chain Fab gene from lymphocyte Ig mRNA. The pComb3H system was used to construct the gene with genetic diversity Preparation of human anti-ZIKV phage antibody library. The purified antibody library was screened by using the purified ZIKV and the obtained ZIKV E protein antigen.@*Results@#The monoclonal antibody Fab fragment gene was successfully obtained for the ZIKV E protein antigen. The gene can be efficiently expressed in Escherichia coli.@*Conclusions@#According to the sequence analysis, this study showed that the monoclonal antibody was a new human genetically engineered antibody against ZIKV, which laid the foundation for the early diagnosis of ZIKV, and obtain a specific monoclonal antibody to ZIKV for human treatment of ZIKV infection.

Preparation and identification human anti-Siglec-9 Fab fragment antibody / 中国免疫学杂志

Objective:The prokaryotic expression vector of human anti-Siglec-9 Fab fragment antibody was constructed and purified,while was identified. Methods:The variable and conserved regions of heavy chain and light chain were obtained by polymerase chain reaction respectively(PCR),which was combined by overlap extension PCR and was digested with restriction enzyme,and then it was transformed into Escherichia coli BL21 and was purified by His-trap Lambda Fab column and AKTA system. SDS-PAGE,ELISA and Western blot were used for the identification of human anti-Siglec-9 Fab fragment antibody. The effect of human anti-Siglec-9 Fab fragment antibody on regulating the mRNA expression of TNF-α,IL-1,IL-6,IL-8 was detected by real-time PCR. Results:Successfully obtained the chains of heavy and light, while constructed an activation human anti-Siglec-9 Fab fragment antibody which could specifically bind to Siglec-9 protein. The human anti-Siglec-9 Fab fragment antibody could specifically bind to Siglec-9 was confirmed by SDS-PAGE,ELISA and Western blot. The human anti-Siglec-9 Fab fragment antibody inhibited the mRNA expression of TNF-α,IL-1, IL-6,IL-8. Conclusion:Successful prokaryotic expression,purification,character analysis,and suppressed the mRNA expression of in-flammatory cytokines with the human anti-Siglec-9 Fab fragment antibody and lay the biology foundation for the further study.

Antibody to FcεRIα Suppresses Immunoglobulin E Binding to High-Affinity Receptor I in Allergic Inflammation

PURPOSE: High-affinity receptor I (FcεRI) on mast cells and basophils plays a key role in the immunoglobulin E (IgE)-mediated type I hypersensitivity mediated by allergen cross-linking of the specific IgE-FcεRI complex. Thus, prevention of IgE binding to FcεRI on these cells is an effective therapy for allergic disease. We have developed a strategy to disrupt IgE binding to FcεRI using an antibody targeting FcεRIα. MATERIALS AND METHODS: Fab fragment antibodies, which lack the Fc domain, with high affinity and specificity for FcεRIα and effective inhibitory activity against IgE-FcεRI binding were screened. IgE-induced histamine, β-hexosaminidase and Ca2+ release in basophils were determined by ELISA. A B6.Cg-Fcer1a(tm1Knt) Tg(FCER1A)1Bhk/J mouse model of passive cutaneous anaphylaxis (PCA) was used to examine the inhibitory effect of NPB311 on allergic skin inflammation. RESULTS: NPB311 exhibited high affinity to human FcεRIα (KD=4 nM) and inhibited histamine, β-hexosaminidase and Ca2+ release in a concentration-dependent manner in hFcεRI-expressing cells. In hFcεRIα-expressing mice, dye leakage was higher in the PCA group than in controls, but decreased after NPB311 treatment. NPB311 could form a complex with FcεRIα and inhibit the release of inflammation mediators. CONCLUSION: Our approach for producing anti-FcεRIα Fab fragment antibody NPB311 may enable clinical application to a therapeutic pathway in IgE/FcεRI-mediated diseases.

Antibody to FcεRIα Suppresses Immunoglobulin E Binding to High-Affinity Receptor I in Allergic Inflammation

PURPOSE: High-affinity receptor I (FcεRI) on mast cells and basophils plays a key role in the immunoglobulin E (IgE)-mediated type I hypersensitivity mediated by allergen cross-linking of the specific IgE-FcεRI complex. Thus, prevention of IgE binding to FcεRI on these cells is an effective therapy for allergic disease. We have developed a strategy to disrupt IgE binding to FcεRI using an antibody targeting FcεRIα. MATERIALS AND METHODS: Fab fragment antibodies, which lack the Fc domain, with high affinity and specificity for FcεRIα and effective inhibitory activity against IgE-FcεRI binding were screened. IgE-induced histamine, β-hexosaminidase and Ca2+ release in basophils were determined by ELISA. A B6.Cg-Fcer1a(tm1Knt) Tg(FCER1A)1Bhk/J mouse model of passive cutaneous anaphylaxis (PCA) was used to examine the inhibitory effect of NPB311 on allergic skin inflammation. RESULTS: NPB311 exhibited high affinity to human FcεRIα (KD=4 nM) and inhibited histamine, β-hexosaminidase and Ca2+ release in a concentration-dependent manner in hFcεRI-expressing cells. In hFcεRIα-expressing mice, dye leakage was higher in the PCA group than in controls, but decreased after NPB311 treatment. NPB311 could form a complex with FcεRIα and inhibit the release of inflammation mediators. CONCLUSION: Our approach for producing anti-FcεRIα Fab fragment antibody NPB311 may enable clinical application to a therapeutic pathway in IgE/FcεRI-mediated diseases.

Construction and primary identification of a naive Fab fragment phage library / 中国免疫学杂志

Objective:To construct a human Fab fragment phage display library and provide a platform for human antibody preparation.Methods:Peripheral blood lymphocytes were collected from healthy donor.The heavy chain Fd fragment and light chain of human immunoglobulin's genes were amplified by RT-PCR,and then cloned into phagemid pComb3XSS to generate human phage antibody library.Cutting with endonucleases such as SacⅠ,XbaⅠ,XhoⅠand SpeⅠto identify the insertion of the light chain or heavy chain Fd genes.IL-2 and digoxin as the antigen was used to scan the phage antibody library.Results:A phage antibody library of Fab had 8.4?107 members and it's recombinant rate was 70%.Through DNA sequencing of one positive clone,it was showed that its heavy chain belonged to IgG subvariety and its light chain to ? family.Conclusion:The success of constructing a nave human phage antibody library proves the useful of phage display system in human antibody preparation,and it can be used to select,purify and express of amylin Fab antibody.

Expression of recombinant humanized anti-HBsAg Fab fragment in genetically engineered Pichia pastoris in high-density fermentation / 解放军医学杂志

Objective To study the expression in high density fermentation of anti HBsAg Fab fragment in Pichia pastoris , and the purification and activity detection of expressed target protein. Method The high density fermentation of genetically engineered Pichia pastoris was proceeded in a 5L bioreactor using fed batch fermentation. The fermentation temperature was set at 28-30℃,the pH was 5 0-5 5, and the DO was kept over 20%. When the absorbance (OD 600 ) of the broth reached 400-450 (the first time of fermentation), 200-250 (the second time), and 300-350 (the third time), the induced phase was initiated, and the methanol concentration was 0 5%-1%. The fermentation ended after 96h's induction, the target protein was purified by affinity chromatography, and its activity was assessed by ELISA. Results It showed that the optimum initial cell density during methanol induced phase should be 300-350, which was good for control of the fermentation process and the expression of recombinant Fab. At the end of the fed batch phase, a yield of about 245mg/l of Fab was reached, and 98% purity could be reached as demonstrated by affinity chromatography. The results of ELISA showed that the supernatant of fermentation and the purified recombinant Fab could bind to HBsAg specifically. Conclusion The success of high density fermentation lays a sound foundation of mass production and clinical applications of recombinant humanized anti HBsAg Fab fragment

Construction of Fab fragment phage antibody library and selection of clones expressing anti-human ?_1-AR antibody / 中国免疫学杂志

Objective:To construct a human Fab phage antibody library and to obtain some recombinant clones which can express Fab fragment antibody against ? 1-adrenergic receptor.Methods:Fd heavy chain gene and ??? light chains gene of IgG obtained by RT-PCR from peripheral lymphocytes of DCM patients whose anti ? 1-AR antibodies are present were cloned into pComb3 vector and the human Fab phage antibody library was constructed.The library was panned by phage display technology with ? 1-ARECⅡ as antigen.Results:A human Fab phage antibody library with 1.4?10 6 capability was constructed successfully,a positive clone against human ? 1-AR was screened from the phage antibody library.Conclusion:The recombinant clones which express Fab antibody against ? 1-AR can be obtained by phage display technology.

Construction of phage antibody library using sensitized in vitro B-lymphocytes of liver cancer patients / 西安交通大学学报(医学版)

Objective To construct human phage antibody library against hepatoma carcinoma.Methods Peripheral blood mononuclear cells(PBMCs) of patients with liver cancer were sensitized in vitro and transformed by Epstein-Barr virus(EBV).The genes of light chain and Fd of antibodies were amplified by RT-PCR.Fab genes were cloned into vector pComb3 and transformed into E.coli XLI-Blue by electroporation to construct the Fab-displaying phage antibody library.Results ELISA detection showed that 4 liver cancer patients' B cells transformed by EBV could produce specific antibodies to hepatoma carcinoma cell.Totally 13 types of light chain genes and 28 types of Fd genes were obtained by RT-PCR.The capacity of the primary phage library was 1.7?107pfu/mL.The percentage of recombinant clones was about 100%.Conclusion A human phage antibody library has been constructed successfully by means of EBV transformation technique.

Study on the purification of recombinant human anti-HBsAg Fab fragment / 解放军医学杂志

Objective The aim of the study was to develop a purification procedure on Pichia pastoris GS115/Fab expressing human anti-HBsAg Fab fragment. Methods Purity and yield ratio and conjugated activity of purified Fab fragment were analyzed with three purified ways of goat anti human Fab affinity chromatography and 14F7 monoclonal antibody affinity column, as well as Ion exchange Size exclusion column. Results 98% purity was reached through 14F7 monoclonal antibody column, and 95% purity was gained after goat anti human Fab fragment column. But yield ratio of the two affinity columns was low, being 35% and 55%, respectively. ForIon exchange Size exclusion column, purity and yield ratio of Fab fragment were very good, being 93.8% and 80% or more, respectively. Results of ELISA analysis showed that purified Fab fragment through three columns could bind to HBsAg specifically. Conclusion The purification process of recombinant anti-HBsAg Fab fragment was established. It lays a foundation for industrialization and clinical research of human anti-HBsAg Fab fragment.