IgY technology: Methods for developing and evaluating avian immunoglobulins for the in vitro detection of biomolecules

Use of Immunoglobulin Y Antibodies: Biosensor-based Diagnostic Systems and Prophylactic and Therapeutic Drug Delivery Systems for Viral Respiratory Diseases

Respiratory viruses have caused many pandemics from past to present and are among the top global public health problems due to their rate of spread. The recently experienced COVID-19 pandemic has led to an understanding of the importance of rapid diagnostic tests to prevent epidemics and the difficulties of developing new vaccines. On the other hand, the emergence of resistance to existing antiviral drugs during the treatment process poses a major problem for society and global health systems. Therefore, there is a need for new approaches for the diagnosis, prophylaxis, and treatment of existing or new types of respiratory viruses. Immunoglobulin Y antibodies (IgYs) obtained from the yolk of poultry eggs have significant advantages, such as high production volumes, low production costs, and high selectivity, which enable the development of innovative and strategic products. Especially in diagnosing respiratory viruses, antibody-based biosensors in which these antibodies are integrated have the potential to provide superiority in making rapid and accurate diagnosis as a practical diagnostic tool. This review article aims to provide information on using IgY antibodies in diagnostic, prophylactic, and therapeutic applications for respiratory viruses and to provide a perspective for future innovative applications.

Preparation of Anti-Zearalenone IgY and Development of an Indirect Competitive ELISA Method for the Measurement of Zearalenone in Post-Fermented Tea

Post-fermented tea (PFT) is one of the most commonly consumed beverages worldwide. Rapid microbial growth and significant changes in the microbial composition of PFT during processing and storage pose a potential risk of contamination with mycotoxins such as zearalenone (ZEN). Screening for ZEN contamination in a simple, rapid, and inexpensive manner is required to ensure that PFT is safe for consumption. To monitor ZEN in PFT, ZEN was conjugated with bovine serum albumin to prepare egg yolk immunoglobulins (IgY). A specific indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on IgY was developed and validated. ZEN was extracted with acetonitrile and water (50:50, v/v) containing 5% acetic acid and purified using a mixture of primary and secondary amines and graphitized carbon black to remove matrix interference from the PFT samples. Under optimal conditions, the linear range of this assay was 13.8-508.9 ng mL-1, the limit of detection was 9.3 ng mL-1, and the half-maximal inhibitory concentration was 83.8 ng mL-1. Cross-reactivity was negligible, and the assay was specific for ZEN-related molecules. The recovery rate of ZEN in the control blanks of PFT samples spiked with a defined concentration of ZEN of 89.5% to 98.0%. The recovery and accuracy of the method were qualified for PFT matrices. No significant differences were evident between the results of the actual PFT samples analyzed by high-performance liquid chromatography and ic-ELISA. The collective data indicate that the developed ic-ELISA can be used for the rapid and simple detection of ZEN in PFT products.

IgY Antibodies from Birds: A Review on Affinity and Avidity

IgY antibodies are found in the blood and yolk of eggs. Several studies show the feasibility of utilising IgY for immunotherapy and immunodiagnosis. These antibodies have been studied because they fulfil the current needs for reducing, replacing, and improving the use of animals. Affinity and avidity represent the strength of the antigen-antibody interaction and directly influence antibody action. The aim of this review was to examine the factors that influence the affinity and avidity of IgY antibodies and the methodologies used to determine these variables. In birds, there are few studies on the maturation of antibody affinity and avidity, and these studies suggest that the use of an adjuvant-type of antigen, the animal lineage, the number of immunisations, and the time interfered with the affinity and avidity of IgY antibodies. Regarding the methodologies, most studies use chaotropic agents to determine the avidity index. Studies involving the solution phase and equilibrium titration reactions are also described. These results demonstrate the need for the standardisation of methodologies for the determination of affinity and avidity so that further studies can be performed to optimise the production of high avidity IgY antibodies.

Anti-SpCas9 IgY Polyclonal Antibodies Production for CRISPR Research Use

The CRISPR/Cas adaptative immune system has been harnessed as an RNA-guided, programmable genome editing tool, allowing for diverse biotechnological applications. The implementation of the system relies on the ability to detect the Cas9 protein in biological samples. This task is facilitated by employing antibodies, which exhibit several advantageous features and applications in the context of tropical neglected diseases. This study reports a one-month immunization scheme with the Cas9 protein fromStreptococcus pyogenes to produce IgY polyclonal antibodies (anti-SpCas9), which can be rapidly isolated by combining yolk de-lipidation with protein salting out using pectin and ammonium sulfate, respectively. Immunodetection assays indicate that the antibodies are highly sensitive, specific, and useful for detecting the SpCas9 protein in promastigotes ofLeishmania braziliensisexpressing exogenous SpCas9. Thus, the simple method for producing anti-SpCas9 IgY antibodies will accelerate CRISPR/Cas-based studies in Leishmania spp. This approach serves as a valuable research tool in this parasite model and holds the potential for wide application in various other biological samples, promoting the implementation of the system. In fact, a bioinformatics approach based on the identification of antigenic determinants in the SpCas9 protein suggests the possibility of using the anti-SpCas9 IgY antibodies in applications such as Prime and Base editing.

IgYs: on her majesty's secret service

There has been an increasing interest in using Immunoglobulin Y (IgY) antibodies as an alternative to "classical" antimicrobials. Unlike traditional antibiotics, they can be utilized on a continual basis without leading to the development of resistance. The veterinary IgY antibody market is growing because of the demand for minimal antibiotic use in animal production. IgY antibodies are not as strong as antibiotics for treating infections, but they work well as preventative agents and are natural, nontoxic, and easy to produce. They can be administered orally and are well tolerated, even by young animals. Unlike antibiotics, oral IgY supplements support the microbiome that plays a vital role in maintaining overall health, including immune system function. IgY formulations can be delivered as egg yolk powder and do not require extensive purification. Lipids in IgY supplements improve antibody stability in the digestive tract. Given this, using IgY antibodies as an alternative to antimicrobials has garnered interest. In this review, we will examine their antibacterial potential.

Development of a Novel Recombinant Full-Length IgY Monoclonal Antibody against Human Thymidine Kinase 1 for Automatic Chemiluminescence Analysis on a Sandwich Biotin-Streptavidin Platform for Early Tumour Discovery

Serum thymidine kinase 1 protein (STK1p) concentration has been used successfully as a reliable proliferating serum biomarker in early tumour discovery and clinical settings. It is detected by an enhanced chemiluminescence (ECL) dot blot assay with the biotin-streptavidin (BSA) platform (a gold standard) based on chicken anti-human thymidine kinase 1 IgY polyclonal antibody (hTK1-IgY-pAb). However, ECL dot blotting is a semiautomatic method that has been limited to large-scale applications due to the differences among batches of antibodies from individual hens, and the skill level of operation technicians sometimes results in unstable STK1p values. Therefore, a highly stable recombinant chicken full-length IgY monoclonal antibody in combination with a fully automated sandwich biotin-streptavidin (sandwich-BSA) platform was developed. Hens were immunized with 31-peptide, a key sequence of human TK1 (hTK1), before constructing an immune phage display scFv library. Finally, a recombinant full-length IgY monoclonal antibody (hTK1-IgY-rmAb#5) with high-affinity binding with human recombinant TK1 (rhTK1) ( $3.95\times {10}^{-10}$  mol/L), high sensitivity with hTK1 calibrators (slope of linear curve: 89.98), and high specificity with low/elevated STK1p ( $r\approx 0.92$ -0.963) was identified. hTK1-IgY-rmAb#5 showed a specific immune response with thymidine kinase 1 (TK1) in TK1-positive/negative cell lysates by Western blotting and immunohistochemistry (IHC) in normal and cancer tissues. In particular, the detection of TK1 serum samples from health centres showed a high coincidence rate ( $r=0.988,n=90$ ) between hTK1-IgY-rmAb#5 and hTK1-IgY-pAb and between the semiautomatic ECL dot blot BSA platform and the novel automatic chemiluminescence sandwich-BSA platform ( $r=0.857,n=292$ ). hTK1-IgY-rmAb#5 is stable and highly sensitive for detecting the lowest STK1p value at 0.01 pmol/L (pM). The accuracy is high ( $\text{SD}<2.5\%$ ) between different batches. It is easy to use the novel hTK1-IgY-rmAb#5 on a new automatic chemiluminescence sandwich-BSA platform. It will be beneficial for large-scale health screenings.

The Impact of Processing and Extraction Methods on the Allergenicity of Targeted Protein Quantification as Well as Bioactive Peptides Derived from Egg

This review article discusses advanced extraction methods to enhance the functionality of egg-derived peptides while reducing their allergenicity. While eggs are considered a nutrient-dense food, some proteins can cause allergic reactions in susceptible individuals. Therefore, various methods have been developed to reduce the allergenicity of egg-derived proteins, such as enzymatic hydrolysis, heat treatment, and glycosylation. In addition to reducing allergenicity, advanced extraction methods can enhance the functionality of egg-derived peptides. Techniques such as membrane separation, chromatography, and electrodialysis can isolate and purify specific egg-derived peptides with desired functional properties, improving their bioactivity. Further, enzymatic hydrolysis can also break down polypeptide sequences and produce bioactive peptides with various health benefits. While liquid chromatography is the most commonly used method to obtain individual proteins for developing novel food products, several challenges are associated with optimizing extraction conditions to maximize functionality and allergenicity reduction. The article also highlights the challenges and future perspectives, including optimizing extraction conditions to maximize functionality and allergenicity reduction. The review concludes by highlighting the potential for future research in this area to improve the safety and efficacy of egg-derived peptides more broadly.

Effect of Catechin on Yolk Immunoglobulin Structure and Properties: A Polyphenol-Protein Interaction Approach

The preparation of the interaction between polyphenols and protein is of great significance for increasing added value and promoting the application of egg yolk immunoglobulin (IgY). This study systematically investigated the effect of catechin on yolk immunoglobulin structural characteristics and functional properties. The binding conditions, force types, molecular conformation, and residual microenvironment of the interaction between catechin and IgY were analyzed by molecular docking technology, UV-vis absorption and fluorescence spectroscopy studies. The results showed that the main binding forces in the complex were hydrogen bonding and van der Waals forces. After the interaction, fluorescence quenching occurred and the maximum emission wavelength was redshifted. The results showed that the microenvironment around IgY increased polarity, increased hydrophilicity and decreased hydrophobicity, and the structure of the peptide chain changed. The bacteriostatic thermal stability of the compound against Escherichia coli and Staphylococcus aureus was lower than that of catechin IgY. The bacteriostatic acid and base stability were higher than that of catechin and IgY. The antioxidant activity was catechin, complex, and IgY, in descending order. The antioxidant activity of catechin and complex was significantly higher than that of IgY. At the same concentration, the apparent viscosity of the three samples was complex, IgY and catechin, in descending order. G' was greater than G" indicating that elastic properties dominate in G". The G' and G" values of the complex were higher than those of the other groups. Rheological results indicated that the complex may have high physical stability. This study provides theoretical support for broadening the application field of IgY and suggest its properties change in the machining process. It also provides new ideas for the development of functional foods from poultry eggs.

IgY Antibodies as Biotherapeutics in Biomedicine

Since the discovery of antibodies by Emil Von Behring and Shibasaburo Kitasato during the 19th century, their potential for use as biotechnological reagents has been exploited in different fields, such as basic and applied research, diagnosis, and the treatment of multiple diseases. Antibodies are relatively easy to obtain from any species with an adaptive immune system, but birds are animals characterized by relatively easy care and maintenance. In addition, the antibodies they produce can be purified from the egg yolk, allowing a system for obtaining them without performing invasive practices, which favors the three “rs” of animal care in experimentation, i.e., replacing, reducing, and refining. In this work, we carry out a brief descriptive review of the most outstanding characteristics of so-called “IgY technology” and the use of IgY antibodies from birds for basic experimentation, diagnosis, and treatment of human beings and animals.

Preclinical Assessment of IgY Antibodies Against Recombinant SARS-CoV-2 RBD Protein for Prophylaxis and Post-Infection Treatment of COVID-19

Within the framework of the current COVID-19 pandemic, there is a race against time to find therapies for the outbreak to be controlled. Since vaccines are still tedious to develop and partially available for low-income countries, passive immunity based on egg-yolk antibodies (IgY) is presented as a suitable approach to preclude potential death of infected patients, based on its high specificity/avidity/production yield, cost-effective manufacture, and ease of administration. In the present study, IgY antibodies against a recombinant RBD protein of SARS-CoV-2 were produced in specific-pathogen-free chickens and purified from eggs using a biocompatible method. In vitro immunoreactivity was tested, finding high recognition and neutralization values. Safety was also demonstrated prior to efficacy evaluation, in which body weight, kinematics, and histopathological assessments of hamsters challenged with SARS-CoV-2 were performed, showing a protective effect administering IgY intranasally both as a prophylactic treatment or a post-infection treatment. The results of this study showed that intranasally delivered IgY has the potential to both aid in prevention and in overcoming COVID-19 infection, which should be very useful to control the advance of the current pandemic and the associated mortality.

Preparation of IgY Oriented Conjugated Fe3O4 MNPs as Immunomagnetic Nanoprobe for Increasing Enrichment Efficiency of Staphylococcus aureus Based on Adjusting the pH of the Solution System

Immunomagnetic separation based on Fe3O4 magnetic nanoparticles (MNPs) has been widely performed in sample pretreatment. The oriented conjugation strategy can achieve a better capture effect than the N-(3-dimethylamlnopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) /N-hydroxysuccinimide (NHS) method. However, immunoglobulin yolk (IgY) cannot be oriented through an SPA strategy like immunoglobulin G (IgG). In this article, an oriented conjugation nanoprobe was prepared for the enrichment of bacteria based on pH adjusting. The main factors affecting the enrichment efficiency were studied, such as the pH of the buffer system, the concentration of IgY, the concentration of nanoprobe, and the enrichment time. Under the optimal conditions, the enrichment efficiency toward target bacteria could reach 92.8%. Combined with PCR, the limit of detection (LOD) was found to be 103 CFU/ml, which was lower than the PCR only. In conclusion, we provided a new protocol for the oriented conjugation of IgY and high sensitivity detection with simple pretreatment.

Mini-review: The market growth of diagnostic and therapeutic monoclonal antibodies - SARS CoV-2 as an example

BACKGROUND

The emergence of novel viruses poses severe challenges to global public health highlighting the crucial necessity for new antivirals.

MAIN BODY

Monoclonal antibodies (mAbs) are immunoglobulins that bind to a single epitope. Mouse mAbs are generated by classic hybridoma technology and are mainly used for immunodiagnostics. For immunotherapy, it is critical to use monoclonal antibodies in their human form to minimize adverse reactions. They have been successfully used to treat numerous illnesses, accordingly, an increasing number of mAbs, with high potency against emerging viruses is the target of every biopharmaceutical company. The diagnostic and therapeutic mAbs market grows rapidly into a multi-billion-dollar business. Biopharmaceuticals are innovative resolutions which revolutionized the treatment of significant chronic diseases and malignancies. Currently, a variety of therapeutic options that include antiviral medications, monoclonal antibodies, and immunomodulatory agents are available for the management of COVID-19.

SHORT CONCLUSION

The invasion of mAbs in new medical sectors will increase the market magnitude as it is expected to generate revenue of about 300 billion $ by 2025. In the current mini-review, the applications of monoclonal antibodies in immune-diagnosis and immunotherapy will be demonstrated, particularly for COVID-19 infection and will focus mainly on monoclonal antibodies in the market.