A Rapid Method for Antigen-Specific Hybridoma Clone Isolation

Production of monoclonal antibodies for therapeutic purposes: A review

Monoclonal antibodies (mAbs) have been used in the development of immunotherapies that target a variety of diseases, such as cancer, autoimmune diseases, and even viral infections; they play a key role in immunization and are expected after vaccination. However, some conditions do not promote the development of neutralizing antibodies. Production and use of mAbs, generated in biofactories, represent vast potential as aids in immunological responses when the organism cannot produce them on their own, these convey unique specificity by recognizing and targeting specific antigen. Antibodies can be defined as heterotetrametric glycoproteins of symmetric nature, and they participate as effector proteins in humoral responses. Additionally, there are different types of mAbs (murine, chimeric, humanized, human, mAbs as Antibody-drug conjugates and bispecific mAbs) discussed in the present work. When these molecules are produced in vitro as mAbs, several common techniques, such as hybridomas or phage display are used. There are several preferred cell lines that function as biofactories, for the production of mAbs, the selection of which rely on the variation of adaptability, productivity and both phenotypic and genotypic shifts. After the cell expression systems and culture techniques are used, there are diverse specialized downstream processes to achieve desired yield and isolation as well as product quality and characterization. Novel perspectives regarding these protocols represent a potential improvement for mAbs high-scale production.

Monoclonal Antibody Discovery Based on Precise Selection of Single Transgenic Hybridomas with an On-Cell-Surface and Antigen-Specific Anchor

Hybridoma technology is widely used for monoclonal antibody (mAb) discovery, whereas the generation and identification of single hybridomas by the limiting dilution method (LDM) are tedious, inefficient, and time- and cost-consuming, especially for hapten molecules. Here, we describe a single transgenic hybridoma selection method (STHSM) that employs a transgenic Sp2/0 with an artificial and stable on-cell-surface anchor. The anchor was designed by combining the truncated variant transmembrane domain of EGFR with a biotin acceptor peptide AVI-tag, which was stably integrated into the genome of Sp2/0 via a piggyBac transposon. To ensure the subsequent precise selection of the hybridoma, the number of on-cell-surface anchors of the transfected Sp2/0 for fusion with immunized splenocytes was further normalized by flow cytometry at the single cell level. Then the single antigen-specific transgenic hybridomas were precisely identified and automatically selected using a CellenONE platform based on the fluorescence assay of the on-cell-surface anchor with the corresponding secreted antigen-specific mAb. The STHSM produced 579 single chloramphenicol (CAP)-specific transgenic hybridomas with a positive rate of 62.7% in 10 plates within 2 h by one-step selection, while only 12 single CAP-specific hybridomas with a positive rate of 6.3% in 40 plates required at least 32 days using the LDM with multiple subcloning steps. The best affinity of mAbs from the STHSM was more than 2-fold higher than that of those from the LDM, and this was mainly due to the preaffinity selection based on the on-cell-surface anchors and more interactions between the mAb and CAP. Then the mAbs from the STHSM and LDM were used to develop an immunoassay for CAP in spiked and natural biological samples. The method displayed satisfactory sensitivity, accuracy, and precision, demonstrating that the STHSM we developed is a versatile, practical, and efficient method for mAb discovery.

Selective retrieval of antibody-secreting hybridomas in cell arrays based on the dielectrophoresis

A cascade of the formation of cell arrays, the discrimination of cells secreting specific molecules, and the selective retrieval of cells has been developed to harvest antibody-secreting hybridomas in heterogeneous cell populations simply and rapidly. The microwell array device consisted of three-dimensional microband electrodes by assembling both upper and lower substrates perpendicularly. Arrays of hybridomas secreting specific antibodies were prepared by aligning hybridomas in each microwell based on the attractive force of positive dielectrophoresis (p-DEP). Antibody secreted by the hybridomas in the microwells was recognized by the antigen immobilized on the microwells or the membrane surfaces of hybridomas to discriminate hybridomas with the secretion ability. Thereafter, a repulsive force of negative dielectrophoresis (n-DEP) was applied to release the target hybridomas from the microwell array. To harvest the target hybridoma, AC signals could be modulated in the n-DEP frequency region and applied to a pair of microband electrodes located above and below each microwell containing target hybridoma. Thus, the cell-based array system described in this study allowed selective retrieval of single target hybridomas by merely switching from p-DEP to n-DEP after selecting the antibody-secreting hybridomas trapped in each microwell. The development of this high-affinity device could be useful to recover hybridomas producing antibodies in large populations of cells rapidly and effectively.

Bacterial coloration immunofluorescence strip for ultrasensitive rapid detection of bacterial antibodies and targeted antibody-secreting hybridomas

The indirect enzyme-linked immunosorbent assay (ELISA) is the gold standard method for monoclonal antibody (McAb) detection and plays a unique role in the preparation of bacterial antibodies. To solve the laborious issues associated with indirect ELISA, a novel bacterial coloration immunofluorescence strip (BCIFS) for antibody detection using colored bacteria instead of a labeled antibody as the antigen and tracer simultaneously and goat anti-mouse IgG as the test line was developed. The affinity range survey of BCIFS indicated that hybridoma cell cultures of E. coli O157:H7 (D3, E7) and Vibrio parahemolyticus (H7, C9) were detected, which complied with the results of indirect ELISA. Compared with the traditional indirect ELISA, the BCIFS sensitivity for E7 cell cultures, ascites, and purified antibodies was at least 4-fold more sensitive, and the BCIFS cross-reactivity for E7 cell cultures was almost consistent with that of indirect ELISA. In addition, the BCIFS isotypes for E. coli O157:H7 cell cultures and Vibrio parahemolyticus were IgG2a and IgG1, respectively, which were identical to the indirect ELISA. Furthermore, the BCIFS method was confirmed by McAb preparation, effective antibody use, and targeted antibody-secreted hybridoma preparation and screening, which showed excellent performance and substitution of the indirect ELISA method. Combined with methylcellulose semisolid medium, BCIFS offers a novel, easy to operate, rapid preparation method for antigen-specific hybridomas. This is the first report using BCIFS instead of indirect ELISA for bacterial antibody detection and application in different samples, which demonstrates a rapid and powerful tool for antibody engineering.

On-site differential diagnostic detection of HP-PRRSV and C-PRRSV using EuNPs-mAb fluorescent probe-based immunoassay

Porcine reproductive and respiratory syndrome virus (PRRSV) has caused worldwide economic losses in the swine industry. Pigs infected with highly pathogenic (HP)-PRRSV display more severe symptoms than those infected with classical (C)-PRRSV. A rapid, sensitive, and reliable detection method to distinguish between HP-PRRSV and C-PRRSV is needed. In this study, we prepared a monoclonal antibody from a hybridoma that can distinguish HP-PRRSV(including TP, QJ, LQ, JN-HS, and TY strain) from C-PRRSV (CH-1A strain) using cell surface-fluorescence immunosorbent assays (CSFIA). Based on this monoclonal antibody (4D5), we developed a europium microsphere-based lateral flow immunochromatographic strip (EuNPs-LFICS) for the differential diagnostic detection of HP-PRRSV and C-PRRSV. Under optimized conditions, the method was rapid (15 min), sensitive (LOD: 2.57 ng mL^-1, 606 TCID50/0.1 mL), selective for HP-PRRSV detection, and quantitative (DLR: 3.56-228 ng mL^-1). In clinical samples, the EuNPs-LFICS assay was largely consistent with PCR results, indicating its practical clinical application.

A new method for rapid screening of hybridoma cell clones secreting paired antibodies using sandwich cell surface fluorescence immunosorbent assay

Traditional methods of screening antibody pairs through ELISA-based methods are time-consuming and burdensome, which is not conducive for the rapid establishment of antigen detection methods. Hence, we developed a new method based on the sandwich cell surface fluorescence immunosorbent assay (SCSFIA) for rapid screening of paired antibodies. In this method, the capture antibodies were anchored to the hybridoma cells membrane through the lipid derivative Oleyl-PEG4000-NHS. Goat anti-mouse antibodies (blocking agent) were added to block the Fc fragment of the capture antibodies. The capture antibodies' Fab fragment can specifically bind the added antigen and form the capture antibodies-antigens complex (immunocomplexes). If the antibodies secreted by hybridoma cells could recognize the immunocomplexes. A double antibody sandwich structure would form on the cell surface based on the specific binding of antigens and antibodies. The hybridoma cells would be stained with anti-mouse IgG-Fc-FITC antibodies. We first used anti-pseudorabies virus (anti-PRV) cells and anti-porcine epidemic diarrhea virus (anti-PEDV) cells to verify the new method. Then, we used this method to successfully screen 5 hybridoma cell clones secreting paired antibodies against Avian influenza A (H7N9) virus within 15 days after fusion. These results showed that this method is suitable for the screening of paired antibodies in a variety of virus. Compared with the traditional method of obtaining paired antibodies, this method can greatly shortens the time needed to screen paired antibodies and improves screening efficiency, indicating that it is a promising method for paired antibodies discovery.

A novel antigen immunochromatography fluorometric strip for rapid detection and application of pathogenic bacterial high-quality antibody

Unlike traditional immunoassay strips, a novel antigen immunechromatography fluorometric strip (AICFS) using inactivated bacterial antigen instead of an antibody as a test line and goat anti-mouse IgG-FITC as a tracer was developed. The applicability survey of AICFS indicated that E. coli O157:H7 (D3) and Acidovorax citrulli (6F) hybridoma cell cultures could be detected, but Vibrio parahemolyticus (H7, C9) hybridoma cell cultures were missed compared with the indirect enzyme-linked immunosorbent assay (ELISA). The four antibody affinity constants (Ka) were measured and compared, and AICFS could be suitable for high-affinity antibody detection. Compared with the traditional indirect ELISA, the AICFS sensitivity for D3 cell cultures, ascites, and purified antibodies was at least 2-fold more sensitive, the AICFS specific for D3 cell cultures by comparative interpretation was compliant except for the strain ATCC 43895, and the indirect ELISA missed it. More importantly, the AICFS method was confirmed by various real samples that it could be used in different scenarios regarding the antibody, including McAb preparation, the effective antibody use, and high-affinity antibody-secreted hybridoma auxiliary preparation and screening. It could be an excellent alternative method with less than 5% corresponding processing time for indirect ELISA method for pathogenic bacterial high-quality antibody detection. This is the first report of using AICFS for bacterial high-quality antibody detection and application in different samples, which demonstrates a rapid auxiliary tool for high-affinity antibody secreted-hybridoma screening and an excellent alternative method for high-quality antibody application.

Hybridoma technology a versatile method for isolation of monoclonal antibodies, its applicability across species, limitations, advancement and future perspectives

The advancements in technology and manufacturing processes have allowed the development of new derivatives, biosimilar or advanced improved versions for approved antibodies each year for treatment regimen. There are more than 700 antibody-based molecules that are in different stages of phase I/II/ III clinical trials targeting new unique targets. To date, approximately more than 80 monoclonal antibodies (mAbs) have been approved. A total of 7 novel antibody therapeutics had been granted the first approval either in the United States or European Union in the year 2019, representing approximately 20% of the total number of approved drugs. Most of these licenced mAbs or their derivatives are either of hybridoma origin or their improvised engineered versions. Even with the recent development of high throughput mAb generation technologies, hybridoma is the most favoured method due to its indigenous nature to preserve natural cognate antibody pairing information and preserves innate functions of immune cells. The recent advent of antibody engineering technology has superseded the species level barriers and has shown success in isolation of hybridoma across phylogenetically distinct species. This has led to the isolation of monoclonal antibodies against human targets that are conserved and non-immunogenic in the rodent. In this review, we have discussed in detail about hybridoma technology, its expansion towards different animal species, the importance of antibodies isolated from different animal sources that are useful in biological applications, advantages, and limitations. This review also summarizes the challenges and recent progress associated with hybridoma development, and how it has been overcome in these years to provide new insights for the isolation of mAbs.

Nanoscale integration of single cell biologics discovery processes using optofluidic manipulation and monitoring

The new and rapid advancement in the complexity of biologics drug discovery has been driven by a deeper understanding of biological systems combined with innovative new therapeutic modalities, paving the way to breakthrough therapies for previously intractable diseases. These exciting times in biomedical innovation require the development of novel technologies to facilitate the sophisticated, multifaceted, high-paced workflows necessary to support modern large molecule drug discovery. A high-level aspiration is a true integration of "lab-on-a-chip" methods that vastly miniaturize cellulmical experiments could transform the speed, cost, and success of multiple workstreams in biologics development. Several microscale bioprocess technologies have been established that incrementally address these needs, yet each is inflexibly designed for a very specific process thus limiting an integrated holistic application. A more fully integrated nanoscale approach that incorporates manipulation, culture, analytics, and traceable digital record keeping of thousands of single cells in a relevant nanoenvironment would be a transformative technology capable of keeping pace with today's rapid and complex drug discovery demands. The recent advent of optical manipulation of cells using light-induced electrokinetics with micro- and nanoscale cell culture is poised to revolutionize both fundamental and applied biological research. In this review, we summarize the current state of the art for optical manipulation techniques and discuss emerging biological applications of this technology. In particular, we focus on promising prospects for drug discovery workflows, including antibody discovery, bioassay development, antibody engineering, and cell line development, which are enabled by the automation and industrialization of an integrated optoelectronic single-cell manipulation and culture platform. Continued development of such platforms will be well positioned to overcome many of the challenges currently associated with fragmented, low-throughput bioprocess workflows in biopharma and life science research.

A new immunochromatographic assay for on-site detection of porcine epidemic diarrhea virus based on monoclonal antibodies prepared by using cell surface fluorescence immunosorbent assay

BACKGROUND

Porcine epidemic diarrhea virus (PEDV) is a highly effective pathogen that can cause death of new-born piglet, resulting in big economical loss in pig farming industry. For rapid detection of PEDV, a new immunochromatographic assay (ICA) based on monoclonal antibodies (mAbs) was developed in this study.

RESULTS

The mAbs were prepared by using PEDV positive hybridoma cells that were selected by using cell surface fluorescence immunosorbent assay (CSFIA). Fourteen mAbs against PEDV strain isolated from south of China were prepared. The optimal mAb 4A11 was coated on NC membrane as the capturing reagent and the mAb A11H7 was coupled to gold nanoparticles (AuNPs) as detection reagent for the new ICA. The new ICA was used to measure PEDV in phosphate buffer containing tween-20. Results indicated that the limit of detection (LOD) of the new ICA was 0.47 μg/mL (5.9 × 10³ TCID₅₀/mL) and the liner detection range of the ICA was 0.625-10 μg/mL (7.8 × 10³-10⁵ TCID₅₀/mL). The specificity analysis results showed that this new ICA had no cross reaction in the presence of other porcine viruses. The ICA was also validated for the detection of PEDV in swine stool samples with little interference from swine stool. To compare its accuracy to other traditional detection methods, 27 swine stool samples from south of China were investigated with the new developed ICA, commercial strip and RT-PCR. Results showed that the new ICA was more comparable to RT-PCR than commercial test strip.

CONCLUSIONS

A new ICA based on mAbs prepared by CSFIA was developed in this study. It was a sensitive, specific and rapid method that could be used for on-site detection of PEDV and therefore was useful for the diagnosis and prevention of PED.