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

The term “IgY technology” was introduced in the literature in the mid 1990s to describe a procedure involving immunization of avian species, mainly laying hens and consequent isolation of the polyclonal IgYs from the “immune” egg yolk (thus avoiding bleeding and animal stress). IgYs have been applied to various fields of medicine and biotechnology. The present article will deal with specific aspects of IgY technology, focusing on the currently reported methods for developing, isolating, evaluating and storing polyclonal IgYs. Other topics such as current information on isolation protocols or evaluation of IgYs from different avian species are also discussed. Specific advantages of IgY technology (e.g., novel antibody specificities that may emerge via the avian immune system) will also be discussed. Recent in vitro applications of polyclonal egg yolk-derived IgYs to the field of disease diagnosis in human and veterinary medicine through in vitro immunodetection of target biomolecules will be presented. Moreover, ethical aspects associated with animal well-being as well as new promising approaches that are relevant to the original IgY technology (e.g., development of monoclonal IgYs and IgY-like antibodies through the phage display technique or in transgenic chickens) and future prospects in the area will also be mentioned.

Specific anti-SARS-CoV-2 S1 IgY-scFv is a promising tool for recognition of the virus

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread globally, a series of vaccines, antibodies and drugs have been developed to combat coronavirus disease 2019 (COVID-19). High specific antibodies are powerful tool for the development of immunoassay and providing passive immunotherapy against SARS-CoV-2 and expected with large scale production. SARS-CoV-2 S1 protein was expressed in E. coli BL21 and purified by immobilized metal affinity chromatography, as antigen used to immunize hens, the specific IgY antibodies were extracted form egg yolk by PEG-6000 precipitation, and the titer of anti-S1 IgY antibody reached 1:10,000. IgY single chain variable fragment antibody (IgY-scFv) was generated by using phage display technology and the IgY-scFv showed high binding sensitivity and capacity to S1 protein of SARS-CoV-2, and the minimum detectable antigen S1 protein concentration was 6 ng/µL. The docking study showed that the multiple epitopes on the IgY-scFv interacted with multiple residues on SARS-CoV-2 S1 RBD to form hydrogen bonds. This preliminary study suggests that IgY and IgY-scFv are suitable candidates for the development of immunoassay and passive immunotherapy for COVID-19 to humans and animals.

Scientometric analysis and perspective of IgY technology study

Egg yolk immunoglobulin (IgY) is a class of antibody that is produced in birds against pathogens. Therefore, hyperimmunization of birds can produce a specific antibody in the egg against target antigen for a wide range of applications in diagnostic, prophylactic or treatment in human and veterinary medicine which is known today as IgY technology. Until now, the number of articles, patents and clinical studies on IgY technology has increased significantly. Hence, there is a fact that scientometric studies are needed to gain a deeper understanding of the research for the commercialization of IgY technology. Until now, no scientometric research has been directed toward IgY technology. In view of this, we conducted scientometric analysis in the WoS database. A total of 1,029 IgY-related papers were obtained including 981 journal articles and 48 reviews. The visualization of this literature showed an increasing trend in the number of IgY-related publications over the 4 decades, especially after 2008 to 2021. China, the United States, Canada, Japan, and Germany had the largest number of publications, with 220, 148, 91, 76, and 72, respectively. Among all the research institutions, Dalian University of Technology, Alberta University and Northwest Agriculture and Forestry University published the most of the articles, respectively. Among authors, Dr. Xiaoying Zhang had the highest number of publications with 21. The top most cited publications were from Dr. da Silva with 38 citations. Keywords co-occurrence network analysis showed that the correlation between different keywords is large, especially IgY, antibodies and immunoglobulin which is consistent with the rapid increase in the number of publications. Finally, through this data analysis, we hope that our result could help IgY technology to more maturity toward industrialization and commercialization.

Generation and evaluation of IgY-scFv based mimetics against canine parvovirus

Antibody mimetics may be used for various biomedical applications, especially those for which conventional antibodies are ineffective. In this study, we developed a smaller molecular chicken IgY mimetic peptide (IgY-peptide) based on the complementarity-determining regions (CDRs) of the anti-canine parvovirus (CPV) IgY-scFv prepared previously. The mimetic peptide showed no cross-reactivity with canine distemper virus (CDV) and canine coronavirus (CCV) and showed excellent protective properties for Crandell-Rees Feline Kidney (CRFK) cells against CPV. This study is the first attempt to develop a mimetic IgY-peptide and demonstrates the ease and feasibility in generating such a novel antibody-like functional molecule for biomedical purposes.