Here at CiteAb we’re always interested to delve a little deeper into the world of antibodies. With CiteAb now listing a number of companies dedicated to the provision of IgY antibodies, we thought it might be a good time to take a closer look.

Without further ado…

What is IgY?

The major serum antibody of birds and reptiles [1], IgY was first described by Klemperer et al. in 1893 but for the better part of the 20th century was known as IgG due to it’s similarity with the mammalian IgG [1,2].

This all changed however in 1969 when the term IgY was coined by Leslie and Clem following their research into the structure and function of chicken immunoglobulins.

As the functional equivalent of IgG in a number of species, IgY behaves as would be expected with regards to ensuring host pathogen clearance. As such it’s performance in biochemical applications is comparable but with a few important differences which I touch on briefly below.

Why use IgY polyclonals?

Here at CiteAb we like to stay neutral when it comes to how we rank the antibodies that we list, preferring instead to leave that job to citations! So to maintain impartiality, what follows are a couple of the key points I’ve compiled from two companies that currently list with CiteAb that specialise in IgY production, taken from their own sites.

 – More antibodies, more easily! As first described by Klemperer, passive immunity in the avia is conferred by the transfer of IgY from serum to egg yolk, wherein it can be found in high quantities. On a per month basis, IgG is produced in mammalian hosts at a rate of ~200mg/month of which 5% is the desired Ig compared to 1,500mg, of which the desired Ig constitutes between 2 and 10% [4]. IgY antibody production exploits this and with no need for bleeding as in conventional IgG immunization, antibodies can be harvested with comparative ease and in higher quantities.

 – IgY lack an fc domain – Because IgY molecules lack an Fc domain, they aren’t bound to by those cells of the mononuclear phagocyte system expressing Fc receptors. This helps minimise false-positive staining in tissue sections containing these cells.

So there we are, a brief introduction to IgY antibodies and how wonderfully timed for Easter 🙂

~ Matt and the CiteAb team


1 – Alexander I. Taylor, Stella M. Fabiane, Brian J. Sutton and Rosaleen A. Calvert. The Crystal Structure of an Avian IgY-Fc Fragment Reveals Conservation with both Mammalian IgG and IgE. Biochemistry, 2009, 48 (3), pp 558–562

2 – Gregory W. Warr, Katharine E. Magor, David A. Higgins. IgY: clues to the origins of modern antibodies. Immunology Today Volume 16, Issue 8, August 1995, Pages 392–398

3 – Gerrie A. Leslie and L. W. Clem. Phylogeny Of Immunoglobulin Structure And Function, III. Immunoglobulins Of The Chicken. J Exp Med. 1969 November 30; 130(6): 1337–1352.

4 – M Tini, U.R Jewell, G Camenisch, D Chilov, M Gassmann. Generation and application of chicken egg-yolk antibodies, Institute of Physiology, Winterthurerstr. 190, CH-8057 Zürich, Switzerland