Flock of chickens
Research Models
Regina Kelder

The Amazing (IgY) Antibody

How a protein derived from the egg yolks of chickens is helping forge new ways of fighting disease

Among the many poignant images from the COVID-19 pandemic have been the first responders—the doctors, nurses, EMT technicians and other health care workers—who day in and day out treat the sick and dying. Inarguably they are putting their own lives on the line every day.

Could nasal drops that contain chicken antibodies to SARS-CoV-2 offer temporary protection? That is what a unique clinical trial in Australia is seeking to determine, and if it works it will be but the latest in a string of projects where Charles River’s Avian Vaccine Services site has been helping to inform groundbreaking research in communicable diseases both on the human and animal fronts. In addition to the COVID-19 study, the distinctive chicken variety of antibodies called immunoglobulin Y (IgY) are effective in eliminating intestinal pathogens in poultry and animal farms and are being looked at as an alternative way to detect host cell proteins in cell lines.

Nastassja Ortega-Heinly, PhD, Director of Laboratory Operations for Avian Vaccine Services at Charles River, is enthusiastic about IgY, and considers its applications in research to be robust. “To be able to apply this to animals and people and potentially cell lines make Avian pretty proud,” says Nastassja. “And we should all have a sense of pride to be involved in something like this. We can all say we played a part in impacting the world.”

COVID-19 Nasal Drops

SPARK GLOBAL®, a non-profit begun by Stanford protein chemist Daria Mochly-Rosen, PhD, is spearheading the work on the nasal drops, which are designed to provide temporary protection by capturing the COVID-19 virus before it even enters the body, thus blocking its transmission.

A news article in Science last year noted that “other protective nasal sprays are in development, but the Stanford approach is unusually low-tech, relying on antibodies harvested from egg yolks of chickens immunized with spike, the surface protein of SARS-CoV-2. Each immunized hen produces an impressive half a gram of IgY in each egg per day.

This is where Charles River Avian Services comes in. The team took a recombinant protein supplied by SPARK at Stanford that targets the spike protein and immunized egg-laying specific pathogen free (SPF) hens, supplied by Charles River, with the protein to induce the production of huge amounts of IgY antibodies against the virus. The antibodies were then transferred to egg yolks and extracted and formulated into nasal drops.

Michael Wallach, Professor Emeritus at University of Technology Sydney, came up with the idea of using chickens for the nasal drops. Wallach, who is the Co-Regional Director of SPARK Oceania in Australia, has made vaccines to protect chickens from disease and tested chicken antibodies in a mouse influenza model.

Likewise, Nastassja’s group had been developing natural antibodies for chickens to protect them from some diseases without the use of antibiotics. So, the notion of delivering antibodies to humans as a prophylactic against the COVID-19 virus made a lot of sense.

“Antibodies target the specific protein of interest, whether that be bacterial or viral, and either prevents or treats disease in both animals and humans,” says Nastassja. “The use of a natural product like this to prevent SARS-CoV-2 infection is a great alternative in preventing disease and spread of the virus. Who knew something that you would have for breakfast could end up saving your life?”

Chicken antibodies also a powerful weapon against bacteria

The IgY found in birds (and reptiles and lungfish blood) differs from mammalian IgG in two separate ways. They do not activate antibody-mediated responses in mammals, which essentially means there is no adverse effect when applied intranasally or orally. The IgY antibody also contains an extra constant domain (on the spine of the Y-shaped protein), and are highly stable at low pH conditions, which helps when applied orally.

Specific Pathogen Free (SPF) chickens, which Charles River’s Avian sites use for veterinary/human vaccine production and research, produce IgY in serum, which is transferred to egg yolks where its concentration increases. This ability has made egg-laying hens extremely valuable not just in combating COVID-19 in humans, but in providing an alternative and highly effective way of protecting poultry against endemic bacteria. It also fits into Charles River’s commitment to the 3Rs by reducing the number of hens needed to produce the same volume of IgY through collection of eggs.

Historically poultry farmers have added antibiotics to the feed to protect animals against infection. But the combination of antibiotics in livestock and the over-prescription of antibiotics for people has contributed to an evolution of bacterial strains that can lead to “superbugs” and the threat of death for people whose infections used to be treatable. Consumers are also becoming aware of the problem and are fighting back with their wallets by demanding poultry products that are antibiotic-free.

Enter IgY antibodies, which involve a different strategy than antibiotics. Here’s how it works. IgY antibodies are added to the drinking water of broiler chickens or other animal farms such as pigs and cows, the IgY binds to targeted bacteria in their gut, preventing colonization of the bacteria. This process leaves the animals free of food-borne pathogens or disease.

“We humans can spend a lot of time thinking about the food that goes into our bodies. In the agricultural industry, people spend even more time thinking about what goes into our food’s bodies,” says Nastassja.

Over the years, scores of studies from multiple laboratories have looked at using IgY from egg yolk of chickens in preventing animal diseases, including norovirus and swine diarrhea. A proof-of-concept study performed by Colorado Quality Research using Charles River Avian Vaccine Service’s anti-C. perfringens IgY in broilers experiencing necrotic enteritis—a disease that has seen an increase since the halt of antibiotic usage—found mortality rates dropped 50% following challenge with the bacteria.

Charles River is now preparing to take this strategy commercially and moving forward with the USDA for licensure of an IgY product that can be used to combat necrotic enteritis.

“There has been an increase over the years in the number of necrotic enteritis cases due to the no antibiotics ever (NAE) or antibiotic free (ABF) programs,” says Nastassja. “This has caused a strain on poultry producers who have invested heavily in these programs. The only effective treatment is antibiotics. A more natural alternative, like IgY, is needed to allow these producers to maintain their claim.”

Assessing Host Cell Proteins

The IgY from egg yolks of hens is also useful in the study of biologics. One of the biggest challenges in making biologics are flagging unwanted host cell proteins (HCPs) that inevitably show up in the finished product, like ants at a picnic. Nano in scale, these trace amounts, nonetheless, can be highly immunogenic—and can ultimately sink a potential biopharmaceutical—so manufacturers work hard to identify and control any impurities in the final product. These HCP assessments have typically been done by using serum from animals—usually rabbits or goats—but IgY from egg yolk of chickens are also being explored to assess traces of HCPs. By using fewer animals, we achieve the same outcome of antibody production, with the added benefit of increased sensitivity.

The uses of IgY appear, well, limitless

Using these IgY antibodies is opening the door to how we prevent viral and bacterial infections in poultry, animal farms, fish and humans, and it could also have a place in the development of large molecule drugs. But IgY’s contributions likely won’t stop here. What can IgY do for you?