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IgY Overview

Find out everything you need to know about IgY from Exalpha

What is IgY?

IgY is an immunoglobulin first described in 1893 when Klemperer1 reported that immunized chickens produce antibodies detectable in their egg yolks as well as their blood. He noted that the concentrations of antibody were similar in both egg yolk and blood, although more recently, it’s been reported that yolk concentrations of IgY are higher2. When Klemperer described chicken immunoglobulins in the late 1800’s, he didn’t name them IgY. For the better part of the 20th century, the predominant immunoglobulin found in chicken blood and egg yolk was known as IgG. It wasn’t until more than 70 years later that the term IgY was coined by Leslie and Clem3, not because the immunoglobulin was found in the yolk, but rather because the avian antibody was sufficiently different and antigenically distinct from the mammalian immunoglobulin counterpart (IgG). It’s now known that IgY is the major immunoglobulin class in birds, reptiles, amphibia and lungfish.

Advantages of IgY

There are several advantages to choosing chickens, rather than rabbit or goats to produce your polyclonal antibodies.

Chickens are not mammals and therefore are more apt to make high-avidity antibodies to mammalian antigens (especially highly conserved mammalian proteins). To our knowledge, it is the most humane way to produce polyclonal antibodies. There is no need to bleed the chicken. Simply collect the eggs.

A single chicken can produce an enormous amount of antibody, up to 3 grams of IgY per month, which is 10-20 times the amount of a rabbit.

Furthermore, compared to rabbits, chickens produce antibody much quicker – high-titre antibody is available from eggs as early as day 25. Our custom IgY production services will deliver 0.5 gram of purified IgY to you within 50-60 days.

Fc region of chicken IgY is sufficiently different from mammalian IgG:

  • Reduces background by not binding to mammalian rheumatoid factors or other naturally occurring anti-mammalian antibodies (e.g. HAMA)
  • Does not activate mammalian complement systems
  • Does not bind to mammalian Fc receptors

Does not bind to standard immunoglobulin-binding proteins such as protein A (Staphylococcus aureus), protein G (Streptococcus sp.), or protein L (Peptostreptococcus magnus)

By having the immunoglobulin Y (IgY) packaged conveniently in eggs, eggs can be stored over a long period of time and the IgY purified from the eggs of desired titre/avidity.

It is cheaper to feed and house chickens than rabbits.

IgY is a stable antibody sharing the following characteristics with mammalian IgG:

  • Divalent
  • Degraded by papain to yield divalent Fab fragment
  • May be enzyme-labeled, biotinylated and gold–labeled by standard procedure

Yolk IgY Purification Kit

IgY EggsPress Purification Kit

Kit Description

Our IgY EggsPress Purification Kit enables researchers to quickly and efficiently purify chicken antibodies (IgY) from the eggs of their immunized chickens without loss of activity. There are many advantages in choosing chickens to raise your polyclonal antibodies.

The disadvantage of using hens is the difficulty of purifying the IgY from the lipid environment of the egg yolk. This problem is circumvented by using our IgY antibody purification kit. Two precipitation steps — one to remove the lipid and the second to precipitate the IgY — provide you with a 90% pure IgY fraction. Expect to purify between 4 and 7 mg IgY per ml egg yolk.

Simply follow the antibody purification Kit Instructions. The entire procedure takes about 4 hours but only 30 minutes is actual hands-on time.

Once you have your IgY, you can treat it like any immunoglobulin. You may wish to label or affinity-purify your antibody. Proceed as you would with any antibody fraction. Keep in mind that IgY does not bind to protein A, protein G, or protein L! Perhaps you want to use your IgY as a primary antibody in an ELISA test, Western blot or immunostaining procedure. A selection of labeled secondary reagents (anti-chicken immunoglobulins) and normal (pre-immune) IgY are available.

How to Produce an IgY Antibody

Many researchers are now choosing to make their custom polyclonal antibody in chickens. There are many reasons to do so. Some choose to immunize a hen and collect the eggs because it is the least invasive way to produce polyclonal antibodies. The eggs can be stored for up to 3 months in the refrigerator or the yolks separated and frozen in delipidation buffer (Reagent A of the Eggspress IgY Purification Kit). For some, the attraction is that chickens often produce better antibodies to conserved mammalian proteins. And for some, choosing hens means that a life-time supply of polyclonal antibody will be available to them after immunizing a single animal. One hen can produce as much antibody as 10 – 20 rabbits, and it’s so much easier to collect eggs than bleed 10 rabbits!

Making an IgY antibody in hens isn’t that different from producing a rabbit antibody, except that it’s easier because bleeding the animal is not necessary. Perhaps the most difficult part of raising antibodies in chickens is to provide a suitable environment for them. Hens prefer to roost on sticks at night, lay their eggs in a nesting box and have regular “dust baths” in sand or wood shavings.

The European Centre for the Validation of Alternative Methods (EVCAM) has reported on a workshop that validates the benefits of using chickens as laboratory animals to produce polyclonal antibodies.

Structure, Function and Physicochemical Properties of IgY

It’s easy to understand why IgY was first categorized as an immunoglobulin G – it’s similar to mammalian IgG (see Figure on right).

Like IgG, IgY also has 2 heavy and 2 light chains, shaped in the characteristic Y shape with an antigen valency of 2. IgY and IgG share a similar sedimentation coefficient of about 7S and both are eluted from DEAE cellulose with low ionic strength buffers. Functionally, they play a similar biological role as well. Both IgG and IgY are the major immunoglobulins providing defense against infectious agents and appear in blood at high concentrations following synthesis of a higher molecular weight antibody (IgM).

There are striking differences however: There is little or no immunological cross-reactivity between IgY and mammalian IgG. IgY has a higher molecular weight due to an extra heavy chain constant domain, lacks a well-defined hinge region and has unique oligosaccharide sidechains1. It has been proposed that the extra domain (CH2) may be the evolutionary precursor to the mammalian IgG hinge region2. IgY is capable of mediating anaphylactic reactions, a function limited to IgE in mammals. In fact, other similarities between IgY and IgE (see Comparison of IgG, IgE, IgY and IgY (ΔFc) and Figure to the right), including similar intrachain disulphide bonding in their extra heavy chain domain, have led some to suggest that IgY is the ancestral molecule to both IgG and IgE3. Molecular genetic studies have confirmed this 4,5,6,7,8