The presence of immunoglobulin Y (IgY) in egg yolks was first reported by Klemperer in 1983 and since 1992 the extraction of polyclonal IgY from chicken eggs has become an attractive alternative method to bleeding animals for immunoglobulin (IgG) antibodies. During egg development, IgY is actively transported into the egg yolk and thus by the time of egg laying up to 200 mg of IgY is present in the yolk. Combining the existing poultry industry’s infrastructure with efficient fractionation and purification of egg yolks provides large scale, economical antibody production.

IgY provides several benefits when compared with mammalian IgG:

• There is a vast evolutionary distance between avian and mammalian species. The result is that IgY will react with more epitopes on a mammalian antigen. Additionally, IgY is not bound by mammalian complement proteins, rheumatoid factors, anti-mouse or anti-human IgG antibodies and Fc-receptors making IgY ideal for bio-analytical applications in human health.
• IgY doesn’t require animal bleeding, the eggs can simply be collected after hen immunization and the maintenance of poultry has a greater cost-benefit ratio compared to that of mammals.

Applicability of IgY in diagnostic virology

Several studies have been performed demonstrating the applicability of IgY in diagnostic virology where IgY can be used as a biological input in immunoassays. In the first outbreak of SARS-CoV, an immunoswab assay was developed to detect the SARS-CoV nucleocapsid protein of the virus and compared the use of an IgG monoclonal antibody (mAb) with a chicken IgY antibody. The detection limit using the IgY antibody was significantly lower (10 pg/mL) compared with mAb IgG (20 – 200 pg/mL) in porcine nasopharyngeal aspirate.¹ 

IgY potential therapeutic for the prevention and treatment of respiratory infections

Additionally, IgY has been tested as a potential therapeutic for prevention and treatment of respiratory infections. Notably, anti-Pseudomonas IgY antibodies have been successfully used to prevent colonization of Pseudomonas aeruginosa in several animal models and is currently undergoing a clinical trial for cystic fibrosis patients.² In the first SARS outbreak anti-SARS-IgYs were evaluated as potential therapeutics and we could similarly look to IgYs now as good candidates for mass production as a SARS-CoV-2 immunotherapeutic.³ 

With low costs and high yields, taking advantage of IgYs has the ability as both diagnostic tools and therapeutic candidates to help solve this current crisis and put the world in a better position to be prepared for the next one.