A monoclonal antibody collection for C. difficile typing ?

Clostridioides difficile is the leading cause of antibiotic-associated diarrhea and pseudomembranous colitis in adults. Various C. difficile strains circulate currently, associated with different outcomes and antibiotic resistance profiles. However, most studies still focus on the reference strain 630 that does not circulate anymore, partly due to the lack of immunological tools to study current clinically important C. difficile PCR ribotypes. The goal of this study was to generate monoclonal antibodies recognizing various epidemic ribotypes of C. difficile. To do so, we immunized mice expressing human variable antibody genes with the Low Molecular Weight (LMW) subunit of the surface layer protein SlpA from various C. difficile strains. Monoclonal antibodies purified from hybridomas bound LMW with high-affinity and whole bacteria from current C. difficile ribotypes with different cross-specificities. This first collection of anti-C. difficile mAbs represent valuable tools for basic and clinical research.

Study on the Antibody Production Efficiency in Modified Big-BALB/c Mice / 实验动物与比较医学

Objective To compare the preparation efficiency of mouse pox and mouse hepatitis antibodies between two substrains of BALB/c and Big-BALB/c (B-BALB/c) mice, and to provide a theoretical basis and reference for the selection of laboratory animals in the preparation of monoclonal antibodies inducedin vivo through hybridoma.Methods Individuals weighing more than 5% of the weight of normal animals at 4 weeks of age (the criterion for late selection is more than 10%) were selected from a population of conventionally bred BALB/c mice and bred individually, and a subline of B-BALB/c mice was prepared after 10 generations of selection. A total of 40 BALB/c mice and 40 B-BALB/c mice aged 10 to 11 weeks, half male and half female, were selected and inoculated with the mousepox monoclonal antibody hybridoma cell line G23 or the murine hepatitis monoclonal antibody hybridoma cell line Y15 pre-treated with liquid paraffin, respectively. Mice ascites containing monoclonal antibodies were obtained by in vivo induction. The antibody titer was tested by indirect ELISA. The mice were grouped based on the sub-strains, gender and inoculation type of hybridoma to analyze the ascites production, antibody titer and antibody production, and to evaluate the antibody preparation efficiency of the two BALB/c mouse sub-strains.ResultsAfter 10 generations of breeding, the body weight of 10-week-old male and female B-BALB/c mice increased by 22.3% and 12.8%, respectively, compared with BALB/c mice of the same age. Compared with BALB/c mice, B-BALB/c mice had better tolerance and adaptation to secondary ascites collection. Compared with BALB/c mice, the ascites production and antibody titer during the preparation of antibodies in B-BALB/c mice were significantly increased, especially in the hybridoma cell line G23 vaccination group (both P＜0.000 1) . After inoculation with the hybridoma cell lines G23 or Y15, the average antibody production of B-BALB/c mice (14.99×104 U and 33.22×104 U) was higher than that of BALB/c mice (5.33×104 U and 19.31×104 U) (both P＜0.01). After inoculation with hybridoma cell line G23, the average antibody production per unit body weight of B-BALB/c mice (0.55×104 U/g) was higher than that of BALB/c mice (0.23×104 U/g) (P＜0.000 1). And the antibody production per unit body weight of female B-BALB/c or BALB/c mice was higher than that of male B-BALB/c or BALB/c mice (bothP＜0.01).Conclusion B-BALB/c mice can be used as an alternative to BALB/c mice in the in vivo induction of monoclonal antibody preparation, which can achieve the purpose of reducing the number of experimental animals used, lowering the labor cost, and improving the efficiency of antibody preparation.

Production of PfEMP1-Specific Mouse Monoclonal Antibodies.

The PfEMP1 family of proteins expressed on the Plasmodium falciparum-infected erythrocyte (IE) surface is the main target of naturally acquired immunity against malaria. Antibodies capable of opsonizing the IEs and blocking the binding between PfEMP1 and human receptors seems to be one of the main protective mechanisms of the naturally acquired immunity. Therefore this family of antigens is intensively studied. Monoclonal antibodies (mAbs) are a very valuable research tool for studying this diverse family of proteins and their interaction with human receptors. As examples, mAbs can be used to identify protective epitopes, epitopes that are targets of cross-reactive antibodies, and the surface expression of specific PfEMP1 variants. Fusing mouse splenocytes with myeloma cells to generate long-lived antibody secreting hybridoma cell lines have been used since the 1970s for the production of mAbs. In this chapter, we describe a simple, reliable, and relatively fast method for producing PfEMP1-specific mAbs from mouse spleen cells using semisolid HAT selection medium.

Monoclonal Antibodies Generation: Updates and Protocols on Hybridoma Technology.

Since its inception in 1975, the hybridoma technology revolutionized science and medicine, facilitating discoveries in almost any field from the laboratory to the clinic. Many technological advancements have been developed since then, to create these "magical bullets." Phage and yeast display libraries expressing the variable heavy and light domains of antibodies, single B-cell cloning from immunized animals of different species including humans or in silico approaches, all have rendered a myriad of newly developed antibodies or improved design of existing ones. However, still the majority of these antibodies or their recombinant versions are from hybridoma origin, a preferred methodology that trespass species barriers, due to the preservation of the natural functions of immune cells in producing the humoral response: antigen specific immunoglobulins. Remarkably, this methodology can be reproduced in small laboratories without the need of sophisticate equipment. In this chapter, we will describe the most recent methods utilized by our Monoclonal Antibodies Core Facility at the University of Texas-M.D. Anderson Cancer Center. During the last 10 years, the methods, techniques, and expertise implemented in our core had generated more than 350 antibodies for various applications.

Hybridoma technology; advancements, clinical significance, and future aspects.

BACKGROUND: Hybridoma technology is one of the most common methods used to produce monoclonal antibodies. In this process, antibody-producing B lymphocytes are isolated from mice after immunizing the mice with specific antigen and are fused with immortal myeloma cell lines to form hybrid cells, called hybridoma cell lines. These hybridoma cells are cultured in a lab to produce monoclonal antibodies, against a specific antigen. This can be achieved by an in vivo or an in vitro method. It is preferred above all the available methods to produce monoclonal antibodies because antibodies thus produced are of high purity and are highly sensitive and specific. Monoclonal antibodies are useful in diagnostic, imaging, and therapeutic purposes and have a very high clinical significance. Once hybridoma cells become stable, these cell lines offer limitless production of homogenized antibodies. This method is also cost-effective. The antibodies produced by this method are highly sensitive and specific to the targeted antigen. It is an important tool used in various fields of research such as in toxicology, animal biotechnology, medicine, pharmacology, cell, and molecular biology. Monoclonal antibodies are used extensively in the diagnosis and therapeutic applications. Radiolabeled monoclonal antibodies are used as probes to detect tumor antigens in the living system; also radioisotope coupled antibodies are used for therapeutic target specific action on oncogenic cells. SHORT CONCLUSION: Presently, the monoclonal antibodies used are either raised in mice or rats; this poses a risk of disease transfer from mice to humans. There is no guarantee that antibodies thus created are entirely virus-free, despite the purification process. Also, there are some immunogenic responses observed against the antibodies of mice origin. Technologically advanced techniques such as genetic engineering helped in reducing some of these limitations. Advanced methods are under development to make lab-produced monoclonal antibodies as human as possible. This review discusses the advantages and challenges associated with monoclonal antibody production, also enlightens the advancement, clinical significance, and future aspects of this technique.

Retroviral Transduction of NKT Hybridoma Cells.

Natural killer T (NKT) cells have been shown to bridge innate and adaptive immunity. However, the rare population and hard-to-transfect of primary NKT cells slow down our understanding of cellular and molecular mechanisms of NKT development and function. To overcome these drawbacks, NKT hybridomas, especially DN32.D3 cells, are applied to study NKT cells in vitro and becoming a valuable tool. Here, we describe the method in the genetic manipulation of DN32.D3 cells by retrovirus, including the generation and concentration of retrovirus, retroviral transduction of DN32.D3 cells, and evaluation of transduction efficiency.

Heterofunctional Particles as Single Cell Sensors to Capture Secreted Immunoglobulins and Isolate Antigen-Specific Antibody Secreting Cells.

Isolating cells based on their secreted proteins remain a challenge. The authors demonstrate a capacity for high throughput single-cell protein secretion analysis and isolation based on heterofunctional particles combined with fluorescence activated cell sorting (FACS). The workflow shows that antibody secreting cells (ASCs) specific for the H1 protein from influenza virus can be isolated from B cells. The workflow consists of incubating anti-CD27 particles with the ASCs, capturing locally secreted immunoglobulins with Protein G on the particles, and identifying immunoglobulins specific to H1 via fluorescent labeled antigens followed by FACS to enrich antigen-specific ASCs. Two particles designs, Janus and mixed, are tested with hybridoma cells. Mixed particles are found to improve antibody collection, while Janus particles are found to bind target cells more effectively. Targeted hybridoma cells in coculture with non-specific hybridoma cells are identified with a sensitivity of 96% and specificity of 98%. Heterofunctional particles are used to capture ASCs that secrete antibodies specific for influenza virus from B cells from healthy adults isolated from blood after vaccination. Positive H1-tetramer sorted ASCs are validated using single ASC cultures and identify 23/56 cells specific for H1 demonstrating 164-fold enrichment from total B cells and 14.6-fold enrichment from total ASCs.

Testing the Impact of Protease Inhibitors in Antigen Presentation Assays.

The major histocompatibility complex (MHC) class I restricted pathway of antigen processing allows the presentation of intracellular antigens to cytotoxic T lymphocytes. The proteasome is the main protease in the cytoplasm and the nucleus, which is responsible for the generation of most peptide ligands of MHC-I molecules. Peptides produced by the proteasome can be further trimmed or destroyed by numerous cytosolic or endoplasmic reticulum (ER) luminal proteases. Small molecule inhibitors are useful tools for probing the role of proteases in MHC class I antigen processing. Here, we describe different methods to test the impact of protease inhibitors in antigen presentation assays.

Development of T cell lines sensitive to antigen stimulation.

Immortalized T cells such as T cell hybridomas, transfectomas, and transductants are useful tools to study tri-molecular complexes consisting of peptide, MHC, and T cell receptor (TCR) molecules. These cells have been utilized for antigen discovery studies for decades due to simplicity and rapidness of growing cells. However, responsiveness to antigen stimulation is typically less sensitive compared to primary T cells, resulting in occasional false negative outcomes especially for TCRs having low affinity to a peptide-MHC complex (pMHC). To overcome this obstacle, we genetically engineered T cell hybridomas to express additional CD3 molecules as well as CD4 with two amino acid substitutions that increase affinity to MHC class II molecules. The manipulated T cell hybridomas that were further transduced with retroviral vectors encoding TCRs of interest responded to cognate antigens more robustly than non-manipulated cells without evoking non-antigen specific reactivity. Of importance, the manipulation with CD3 and mutated human CD4 expression was effective in increasing responsiveness of T cell hybridomas to a wide variety of TCR, peptide, and MHC combinations across class II genetic loci (i.e. HLA-DR, HLA-DQ, HLA-DP, and murine H2-IA) and species (i.e. both humans and mice), and thus will be useful to identify antigen specificity of T cells.

Purification and characterization of monoclonal IgG antibodies recognizing Ebola virus glycoprotein.

PURPOSE: The goal of this study was to purify and characterize Ebola virus glycoprotein (GP)-specific IgG antibodies from hybridoma clones. MATERIALS AND METHODS: For hybridoma production, mice were injected by intramuscular-electroporation with GP DNA vaccines, and boosted with GP vaccines. The spleen cells were used for producing GP-specific hybridoma. Enzyme-linked immunosorbent assay, Western blot assay, flow cytometry, and virus-neutralizing assay were used to test the ability of monoclonal IgG antibodies to recognize GP and neutralize Ebola virus. RESULTS: Twelve hybridomas, the cell supernatants of which displayed GP-binding activity by enzyme-linked immunosorbent assay and the presence of both IgG heavy and light chains by Western blot assay, were chosen as a possible IgG producer. Among these, five clones (C36-1, D11-3, D12-1, D34-2, and E140-2) were identified to secrete monoclonal IgG antibodies. When the monoclonal IgG antibodies from the 5 clones were tested for their antigen specificity, they recognized GP in an antigen-specific and IgG dose-dependent manner. They remained reactive to GP at the lowest tested concentrations (1.953-7.8 ng/mL). In particular, IgG antibodies from clones D11-3, D12-1, and E140-2 recognized the native forms of GP expressed on the cell surface. These antibodies were identified as IgG1, IgG2a, or IgG2b kappa types and appeared to recognize the native forms of GP, but not the denatured forms of GP, as determined by Western blot assay. Despite their GP-binding activity, none of the IgG antibodies neutralized Ebola virus infection in vitro, suggesting that these antibodies are unable to neutralize Ebola virus infection. CONCLUSION: This study shows that the purified IgG antibodies from 5 clones (C36-1, D11-3, D12-1, D34-2, and E140-2) possess GP-binding activity but not Ebola virus-neutralizing activity.

Automated Single-Cell Analysis and Isolation System: A Paradigm Shift in Cell Screening Methods for Bio-medicines.

We have developed an automated robot that facilitates non-invasive isolation of a single cell with the most favorable properties from arrays containing >105 cells, thus allowing the establishment of new cell screening methods for bio-medicines. In this chapter, an outline of the proposed automated single-cell analysis and isolation system (hereafter called 'single-cell robot') is reviewed by comparison with a conventional fluorescence-activated cell sorter (FACS). The single-cell robot could perform high-throughput screening for both mammalian cells secreting the highest amount of bio-medicines (e.g. Chinese hamster ovary (CHO) cells or hybridomas), and stem cells with the highest pluripotency (e.g., embryonic stem (ES) cells), from huge number of cell libraries based on the recently proposed concept of "single cell-based breeding". The rational screening method for the de novo agonist design could also be performed using yeast cells expressing functional mammalian cytokine receptors (e.g., epidermal growth factor receptor (EGFR), somatostatin G protein-coupled receptor (SSTR5), and interleukin 5 receptor (IL5R)). Furthermore, the single-cell robot could comprehensively analyze the reaction between olfactory sensory neurons and specific odorants, which will shed light on how odorants are recognized by olfactory receptors. Taken together, these unique features of the proposed single-cell robot will contribute to the high-throughput development of forthcoming bio-medicines.

Multiplexed Quantitation of Intraphagocyte Mycobacterium tuberculosis Secreted Protein Effectors.

The pathogenic potential of Mycobacterium tuberculosis largely depends on ESX secretion systems exporting members of the multigenic Esx, Esp, and PE/PPE protein families. To study the secretion and regulation patterns of these proteins while circumventing immune cross-reactions due to their extensive sequence homologies, we developed an approach that relies on the recognition of their MHC class II epitopes by highly discriminative T cell receptors (TCRs) of a panel of T cell hybridomas. The latter were engineered so that each expresses a unique fluorescent reporter linked to specific antigen recognition. The resulting polychromatic and multiplexed imaging assay enabled us to measure the secretion of mycobacterial effectors inside infected host cells. We applied this novel technology to a large panel of mutants, clinical isolates, and host-cell types to explore the host-mycobacteria interplay and its impact on the intracellular bacterial secretome, which also revealed the unexpected capacity of phagocytes from lung granuloma to present mycobacterial antigens via MHC class II.

Purification and characterization of monoclonal IgG antibodies recognizing Ebola virus glycoprotein

PURPOSE: The goal of this study was to purify and characterize Ebola virus glycoprotein (GP)-specific IgG antibodies from hybridoma clones. MATERIALS AND METHODS: For hybridoma production, mice were injected by intramuscular-electroporation with GP DNA vaccines, and boosted with GP vaccines. The spleen cells were used for producing GP-specific hybridoma. Enzyme-linked immunosorbent assay, Western blot assay, flow cytometry, and virus-neutralizing assay were used to test the ability of monoclonal IgG antibodies to recognize GP and neutralize Ebola virus. RESULTS: Twelve hybridomas, the cell supernatants of which displayed GP-binding activity by enzyme-linked immunosorbent assay and the presence of both IgG heavy and light chains by Western blot assay, were chosen as a possible IgG producer. Among these, five clones (C36-1, D11-3, D12-1, D34-2, and E140-2) were identified to secrete monoclonal IgG antibodies. When the monoclonal IgG antibodies from the 5 clones were tested for their antigen specificity, they recognized GP in an antigen-specific and IgG dose-dependent manner. They remained reactive to GP at the lowest tested concentrations (1.953–7.8 ng/mL). In particular, IgG antibodies from clones D11-3, D12-1, and E140-2 recognized the native forms of GP expressed on the cell surface. These antibodies were identified as IgG1, IgG2a, or IgG2b kappa types and appeared to recognize the native forms of GP, but not the denatured forms of GP, as determined by Western blot assay. Despite their GP-binding activity, none of the IgG antibodies neutralized Ebola virus infection in vitro, suggesting that these antibodies are unable to neutralize Ebola virus infection. CONCLUSION: This study shows that the purified IgG antibodies from 5 clones (C36-1, D11-3, D12-1, D34-2, and E140-2) possess GP-binding activity but not Ebola virus-neutralizing activity.

Preparation and identification of monoclonal antibody against BNTN3 A3 / 军事医学

Objective To prepare and identify monoclonal antibodies against BTN 3A3.Methods BALB/c mice were immunized with the BTN3A3 recombinant protein BTN3A3-mFc containing the mouse IgG2a Fc tag as an antigen, and hybridoma cells were obtained by cell fusion .BTN3A3 recombinant protein BTN3A3-hFc containing a human IgG1 Fc tag as a detection target was used to screen hybridoma cell lines secreting monoclonal antibodies against BTN 3A3.The above monoclonal antibodies were identified with Western blot and indirect immunofluorescence .Results Seven hybridoma cell lines that could stably secret BTN 3A3 monoclonal antibodies were obtained . ELISA, Western blot and indirect immunofluorescence showed that the above antibodies specifically recognized BTN 3A3.Conclusion BTN3A3 monoclonal antibodies that can be applied to ELISA , Western blot or immunofluorescence have been obtained , which can contribute to the functional study of BTN3A3.

Simultaneous production of monoclonal antibodies against Bacillus thuringiensis (Bt) Cry1 toxins using a mixture immunization.

The detections of Cry1 toxins are mainly dependent on immunoassays based on specific monoclonal antibodies (mAb). In the present study, a mixture immunization with seven Cry1 toxins was administered. The results showed that five mAbs with different characteristics, especially one mAb named 5-E8 which could recognize all the seven Cry1 toxins were obtained. Based on the 5-E8 mAb, a double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) which can specifically detect the seven Cry1 toxins without cross-reactivity to Cry2A and vip3 was developed with the limit of detection (LOD) and limit of quantification (LOQ) of 6.37-11.35 ng mL-1 and 17.36-24.48 ng mL-1, respectively. The recovery tests showed that the recoveries ranged from 78% to 110% within the quantitation range (LOQ-100 ng mL-1). The established DAS-ELISA can be a useful tool for monitoring the Cry1 toxins in agricultural products. Mixture immunization opens a new path for producing diverse mAbs simultaneously in a single immunization circle.

The preparation of the mouse monoclonal antibodies specific for the DNAH2 protein / 天津医药

Objective To prepare specific mouse monoclonal antibodies against Homo sapiens dynein,axonemal, heavy chain 2 (DNAH2). Methods Firstly, recombinant plasmid encoding His tagged immunogen, targeting N-terminal sequence of DNAH2 protein (1-300 aa), in E. coli was constructed. IPTG was used to induce the expression of His-immunogen, which was then purified and immunized in BALB/c mice. Hybridoma cells were obtained through the fusion between myeloma cells and splenocytes isolated from BALB/c mice. Finally, ELISA and Western blot assays were performed to screen the positive hybridoma. Results IPTG was used efficiently to induce the expression of DNAH2 immunogen in E. coli. DNAH2 protein bands were detected in screened positive hybridoma. Conclusion Mouse monoclonal anti-DNAH2 antibody is prepared successfully.

Single-cell-based breeding: Rational strategy for the establishment of cell lines from a single cell with the most favorable properties.

For efficient biomolecule production (e.g., antibodies, recombinant proteins), mammalian cells with high expression rates should be selected from cell libraries, propagated while maintaining a homogenous expression rate, and subsequently stabilized at their high expression rate. Clusters of isogenic cells (i.e., colonies) have been used for these processes. However, cellular heterogeneity makes it difficult to obtain cell lines with the highest expression rates by using single-colony-based breeding. Furthermore, even among the single cells in an isogenic cell population, the desired cell properties fluctuate stochastically during long-term culture. Therefore, although the molecular mechanisms underlying stochastic fluctuation are poorly understood, it is necessary to establish excellent cell lines in order to breed single cells to have higher expression, higher stability, and higher homogeneity while suppressing stochastic fluctuation (i.e., single-cell-based breeding). In this review, we describe various methods for manipulating single cells and facilitating single-cell analysis in order to better understand stochastic fluctuation. We demonstrated that single-cell-based breeding is practical and promising by using a high-throughput automated system to analyze and manipulate single cells.

Preparation and Preliminary Application of Monoclonal Antibody Against Carcinoembryonic Antigen Glypican-3 / 天津医药

Objective To prepare monoclonal antibody specifically against carcinoembryonic antigen glypican-3 (GPC3) and its preliminary application. Methods GPC3 was cloned with PCR to pET16b vector and expressed in E. co-liBL21. Spleen cells were obtained from Balb/c mice embedding immunized with purified antigen intraperitoneally, and fused with Sp2/0 cells. Hybridoma cells were screened by indirect ELISA, and identified by Western blot assay using puri-fied protein after the cell fusion. The indirect immunofluorescence method was used to detect the GPC3 expression in HepG2 cell line. Results The prokaryotic expression vector of GPC3 was successfully constructed, and GPC3 was stably expressed in E. coliBL21. A mouse hybridoma cell line secreting monoclonal antibody to GPC3 was obtained. Western blot analysis showed that monoclonal antibody specifically recognized recombinant protein. Monoclonal antibody could be used to detect GPC3 protein expression in HepG2 cell line by indirect immunofluorescence. Conclusion The monoclonal antibody against GPC3 was successfully obtained.

Human monoclonal antibodies derived from memory B cells following live attenuated dengue virus vaccination or natural infection exhibit similar characteristics.

The immunopathogenesis of severe dengue is poorly understood, but there is concern that induction of cross-reactive nonneutralizing antibodies by infection or vaccination may increase the likelihood of severe disease during a subsequent infection. We generated a total of 63 new human monoclonal antibodies to compare the B-cell response of subjects who received the National Institutes of Health live attenuated dengue vaccine rDEN1Δ30 to that of subjects following symptomatic primary infection with DENV1. Both infection and vaccination induced serum neutralizing antibodies and DENV1-reactive peripheral blood B cells, but the magnitude of induction was lower in vaccinated individuals. Serotype cross-reactive weakly neutralizing antibodies dominated the response in both vaccinated and naturally infected subjects. Antigen specificities were very similar, with a slightly greater percentage of antibodies targeting E protein domain I/II than domain III. These data shed light on the similarity of human B-cell response to live attenuated DENV vaccine or natural infection.

Production of monoclonal antibodies.

This unit describes the production of monoclonal antibodies beginning with immunization, cell fusion, and selection. Support protocols are provided for screening primary hybridoma supernatants for antibodies of desired specificity, establishment of stable hybridoma lines, cloning of these B cell lines by limiting dilution to obtain monoclonal lines, and preparation of cloning/expansion medium. An alternate protocol describes cell fusion and one-step selection and cloning of hybridomas utilizing a semi-solid methylcellulose-based medium (ClonaCell-HY from StemCell Technologies).