Establishment of a sandwich ELISA for bovine plasma PON-1 and its predictive capabilities for dairy cows with fatty liver

The aim of this study to improve the clinical diagnosis of fatty livers (FL) in dairy cows by using the paraoxonase-1 (PON-1) enzyme as a detection index. Prokaryotic expression technology was used to generate recombinant bovine PON-1 protein. Mice were immunized with this protein to generate hybridoma cells, stably secreting anti-PON-1. Cells were injected into the peritoneal cavity of mice, and ascites were purified to generate bovine PON-1 monoclonal antibody. Rabbits were then immunized with this antigen, and a polyclonal antibody against bovine PON-1 was obtained. Using monoclonal and polyclonal antibodies, a double-antibody sandwich ELISA for plasma PON-1 was constructed. Plasma samples were collected from healthy (n = 13) and FL (n = 13) cows, and plasma PON-1 levels were detected using the PON-1 ELISA. Receiver operating characteristic curve (ROC) analysis was used to analyze correlations between PON-1 levels and FL. Results showed that the ideal working concentration of the monoclonal antibody was 0.8 mg/mL, and the quantitative detection limit was 90 ng/mL. Plasma PON-1 levels were significantly lower in FL cows, when compared with healthy animals. It is concluded that PON-1 ELISA predicts risk factors for dairy cows with FL. PON-1 levels in plasma can be used as an early warning indicator for FL and concentration of 61.87 nmol/L was identified as warning index.

Class-Switching of B Lymphocytes by DNA and Cell Immunization for Stereospecific Monoclonal Antibodies against Native GPCR

To develop efficient applications of monoclonal antibodies for therapeutic purposes, stereospecific recognition of the target antigens is needed. DNA immunization is one of the best methods for sensitizing B lymphocytes that can produce conformation-specific antibodies. Here we verified the class-switching of monoclonal antibodies by DNA immunization followed by cell immunization for the generation of stereospecific monoclonal antibodies against native G protein-coupled receptor (GPCR) using the optimized stereospecific targeting (SST) technique. This technology facilitates the efficient selection of sensitized B lymphocytes through specific interaction with the intact antigen via B-cell receptors (BCRs). We demonstrate that multiple DNA immunizations followed by a single cell immunization in combination with a longer sensitization period (three to four months) are an appropriate sensitizing strategy for the generation of IgG-type stereospecific monoclonal antibodies by class-switching, and the characteristics of antibody production could be transferred to hybridoma cells provided by the optimized SST technique.

Idiotype vaccines produced with a non-cytopathic alphavirus self-amplifying RNA vector induce antitumor responses in a murine model of B-cell lymphoma

A promising therapy for patients with B-cell lymphoma is based on vaccination with idiotype monoclonal antibodies (mAbs). Since idiotypes are different in each tumor, a personalized vaccine has to be produced for each patient. Expression of immunoglobulins with appropriate post-translational modifications for human use often requires the use of stable mammalian cells that can be scaled-up to reach the desired level of production. We have used a noncytopathic self-amplifying RNA vector derived from Semliki Forest virus (ncSFV) to generate BHK cell lines expressing murine follicular lymphoma-derived idiotype A20 mAb. ncSFV/BHK cell lines expressed approximately 2 mg/L/24 h of A20 mAb with proper quaternary structure and a glycosylation pattern similar to that of A20 mAb produced by hybridoma cells. A20 mAb purified from the supernatant of a ncSFV cell line, or from the hybridoma, was conjugated to keyhole limpet hemocyanin and used to immunize Balb/c mice by administration of four weekly doses of 25 µg of mAb. Both idiotype mAbs were able to induce a similar antitumor protection and longer survival compared to non-immunized mice. These results indicate that the ncSFV RNA vector could represent a quick and efficient system to produce patient-specific idiotypes with potential application as lymphoma vaccines.

Evaluation the Reactivity of a Peptide-Based Monoclonal Antibody with Drug Resistant Pulsotypes of Acinetobacter Baumannii as Potential Therapeutic Approach

Background: Acinetobacter baumannii is an opportunistic and antibiotic-resistant pathogen that predominantly causes nosocomial infections. There is urgent need for development nonantibiotic-based treatment strategies. We developed novel monoclonal antibody (mAb) against a peptide of conserved outer membrane protein A (OmpA) and evaluated its reactivity with different pulsotypes of A.baumannii. Materials and Methods: Peptide derived from A.baumannii OmpA was conjugated to keyhole limpet hemocyanin and injected into Balb/c mice. Splenocytes of immunized mice were fused with SP2/0 myeloma cells followed by selection of antibody-producing hybridoma cells. After screening of different hybridoma colonies by ELISA, one monoclone was selected as 3F10-C9 and the antibody was tested for reaction with five different Acinetobacter pulsotypes that were resistant to carbapenem antibiotics. The affinity constant was measured by ELISA. The ELISA, Western blotting, indirect immunofluorescence (IFA), and in vitro Opsonophagocytosis assays were used to evaluate the reactivity of generated mAb. Results: The anti-OmpA antibody reacted with the immunizing peptide and had a high affinity (around 1.94 × 10 − 9 M) for its antigen in the ELISA. Specific binding of mAb to OmpA was confirmed in Western blot. IFA assays revealed that mAb recognized specific OmpA on the pulsotypes. Opsonophagocytosis assays showed that the mAb increased bactericidal activity of macrophage cells. The antibody function was higher in the presence of serum complement. Conclusion: The peptide-based mAb demonstrated optimal performance in laboratory experiments which may be appropriate in investigation on OmpA in Acinetobacter pathogenesis and development of passive immunization as novel therapeutic approach.

891 S-531011, a novel anti-human CCR8 antibody: antibody screening and evaluation of biological profiles

BackgroundRegulatory T cells (Tregs) are involved in tumor progression and inhibition of anti-tumor immune responses by promotion of immunological tolerance in the tumor microenvironment. On the other hand, Treg cells in peripheral blood are also essential role in preventing autoimmunity and uncontrolled inflammation. So, selective control of tumor infiltrating Treg cells might be an attractive approach of immune-oncology therapies without disrupting their systemic anti-inflammatory functions. Here, we focused on CCR8 (C-C motif chemokine receptor 8) as a target molecule which was selectively and highly expressed on tumor-infiltrating Tregs and developed a novel anti-human CCR8 specific antibody.MethodsWe immunized mice with human CCR8 by our original immunization method which could strongly induce antibodies for membrane proteins, and then constructed hybridoma cells. Anti-human CCR8 (human CCR4 as a negative control) binding assay and human CCL1-CCR8 neutralizing assay were simultaneously performed by using supernatants of hybridoma cells to isolate human CCR8 specific strong-neutralizing antibodies. After humanization and affinity maturation of some selected clones, we selected our lead antibody by binding specificity, neutralizing activity, antibody dependent cellular cytotoxicity (ADCC) and thermodynamic stability as index.ResultsWe rapidly induced human CCR8 specific antibodies in mouse with our unique immunization methods and constructed thousands of hybridomas secreting anti-human CCR8 antibodies. We also successfully humanized some of lead antibodies which show high affinity and specificity and isolated novel anti-human CCR8 specific humanized antibody S-531011 as our development antibody after affinity maturation. S-531011 selectively recognizes human CCR8 on the surface of tumor-infiltrating Tregs and shows strong ADCC. While human CCL1 is known as a dominant ligand of CCR8 which binds extracellular loop2 and N-terminal of CCR8, S-531011 recognizes similar epitopes and effectively neutralizes CCL1-CCR8 signaling. Furthermore, S-531011 also shows favorable blood kinetics in vivo and potently inhibits tumor growth in tumor bearing human CCR8 knock-in mouse model.ConclusionsWe develop S-531011, a novel anti-human CCR8 humanized antibody which could selectively recognize and deplete tumor infiltrating Tregs. Based on our pre-clinical data, S-531011 has strong anti-tumor effect and we expect that it might be a potent novel tumor immuno-therapeutic agent with fewer side effect.Ethics ApprovalThe present study was approved by the Institutional Ethics Committee of Osaka University Hospital (approved number: 13266-15). Animal studies were approved by the Institutional Animal Care and Use Committee (approved number: S20192D, S20197D and S20198D).

Development of enzyme immunoassay for detecting I and II types of shiga-like toxins

Introduction. The aim of the work was development of enzyme immunoassay for detecting I and II types of shiga-like toxins and assessment of it diagnostic properties. Materials and methods. For the research, we used hybridomas producing monoclonal antibodies to shiga-like toxins of types I and II, obtained at the branch of the Federal State Budgetary Institution “48 Central Research Institute” of the Ministry of Defense of Russian Federation (Kirov); BALB/c mice; shiga-like toxins of types I and II. Hybridoma cells were cultured in culture flasks and in the peritoneal cavity of BALB/c mice. Monoclonal antibodies were isolated from ascitic fluids by precipitation with a saturated solution of ammonium sulfate, followed by purification by ion exchange chromatography. The obtained preparations of monoclonal antibodies were used to develop enzyme immunoassay for the detection of shiga-like toxins of types I and II. Specific components of enzyme immunoassay were freeze-dried in a protective environment. Results. As a result of research, preparative quantities of monoclonal antibodies against I and II types of shiga-like toxins were obtained and purified; selection of monoclonal antibodies for sorption on the solid phase and for the synthesis of immunoperoxidase conjugates was carried out. Conclusion. experimental enzyme immunoassay allowing to identify 1 ng/ml I and II types of shiga-like toxins in «sandwich»-ELISA was developed.

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. Main body of the abstract 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.

Antibody Therapy: Past, Present and Future

The emergence of pandemics like SARS-CoV-2 and a gradual increase in Multidrug Resistant (MDR) infections highlights the need of innovation in therapeutics. Antibodies are one of the potential solutions for long. Antibody therapy has come very long way from the fight against infectious diseases, bacterial toxins to hybridoma technology and monoclonal antibodies. Hybridoma cells receive a deserving attention due to their antigen-specificity. But, as they were murine in origin, Human Anti Murine Antibody (HAMA) emerged. To achieve this, phage display was introduced. The emergence of molecular cloning lead to the generation of genetically engineered recombinant antibodies such as Fab, Fc, Variable Fragment (Fv), Single Chain Variable Fragments (scFv), single domain antibodies, diabodies; like scFv fragments to different moieties, such as drugs toxins, radionuclides, liposomes or quantum dots etc. Minimized antibodies have several advantages like rapid blood clearance, reduced immunogenicity, low retention time in non-target tissues, access to cryptic epitopes facilitating tumor penetration, rapid growth facilitating higher yield and lower production cost. This paper gives an overview of the history of development of antibodies and its fragments as potential therapeutic agents for the treatment of infectious diseases, one of the biggest challenges of humanity.

Nicotiana spp. for the Expression and Purification of Functional IgG3 Antibodies Directed Against the Staphylococcus aureus Alpha Toxin

Immunoglobulin subclass IgG1 is bound and neutralized effectively by Staphylococcus aureus protein A, allowing the bacterium to evade the host’s adaptive immune response. In contrast, the IgG3 subclass is not bound by protein A and can be used to treat S. aureus infections, including drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA). However, the yields of recombinant IgG3 are generally low because this subclass is prone to degradation, and recovery is hindered by the inability to use protein A as an affinity ligand for antibody purification. Here, we investigated plants (Nicotiana spp.) as an alternative to microbes and mammalian cell cultures for the production of an IgG3 antibody specific for the S. aureus alpha toxin. We targeted recombinant IgG3 to different subcellular compartments and tested different chromatography conditions to improve recovery and purification. Finally, we tested the antigen-binding capacity of the purified antibodies. The highest IgG3 levels in planta (>130 mg kg−1 wet biomass) were achieved by targeting the endoplasmic reticulum or apoplast. Although the purity of IgG3 exceeded 95% following protein G chromatography, product recovery requires further improvement. Importantly, the binding affinity of the purified antibodies was in the nanomolar range and thus comparable to previous studies using murine hybridoma cells as the production system.

Inducing, Collecting, and Storing Ascites

Ascitic fluid (also called ascites) is an intraperitoneal fluid extracted from mice that have developed a peritoneal tumor. For antibody production, the tumor is induced by injecting hybridoma cells into the peritoneum, which serves as a growth chamber for the cells. The hybridoma cells grow to high densities and continue to secrete the antibody of interest, thus creating a high-titered solution of antibodies for collection. A single mouse may yield as much as 10 mL of ascitic fluid or as little as 1 mL per batch. Antibody concentrations will typically be between 1 and 10 mg/mL. The most common problem encountered in storing ascites is contamination of these solutions with bacteria or fungi. This can be prevented by the addition of sodium azide.