Introduction of IgY
The function of the IgY molecule is analogous to that of mammalian IgG. However, although both immunoglobulins contain two Fab arms, which include both variable domains of the light chain and the first two constant domains of the heavy chain, their structures show some differences. Unlike IgG, which has three constant domains in the heavy chain, IgY contains four heavy-chain constant domains. According to mass spectrophotometry analysis, the molecular weight of IgG is ~160 kDa, whereas that of IgY is ~167 kDa (heavy chain 65 kDa and light chain 19 kDa). However, according to SDS-PAGE analysis, under reducing conditions, one band of ~70 kDa (heavy chain) and another of ~25 kDa (light chain) can be observed, while under non particularly stable at high temperatures and across a diverse range of pHs.
Fig. 1 The canonical structures of IgG and IgY. (Thirumalai, 2019)
The production, extraction, and use of specific IgY antibodies from egg yolk is an innovative method to produce antibodies for passive immunotherapy and prophylaxis. One of the advantages of this technology is that IgY is obtained directly from the eggs and not from blood, a fact that greatly reduces animal harm and distress. Another advantage of IgY-technology, based on the phylogenetic distance between birds and mammals, is that it is possible to obtain antibodies against highly conserved mammalian proteins or against proteins that usually evade the immune system in mammals. Due to the lack of recognition of mammalian Fc receptors, the usage of IgY may improve human diagnostic platforms by reducing the interference with rheumatoid factors and human anti-mouse antibodies. In addition, IgY does not trigger the mammalian complement activation in vitro or in vivo.
Fig. 2 Timeline of IgY-technology. (Leiva, 2020)
IgY purification by means of protein A (Staphylococcus aureus) or protein G (Streptococcus species, strains C and G) affinity columns is not possible, since these proteins have no binding site for IgY. The choice of a suitable IgY purification method is influenced by the scale of purification (laboratory or industrial), cost-effectiveness, technology, and impact on the environment (waste management).
- Precipitation methods: Involving ammonium or sodium sulfate, polyethyleneglycol (PEG), caprylic acid, and carrageenin.
- Chromatographic methods: Affinity chromatography, ion-exchange chromatography, hydrophobic interaction chromatography, thiophylic interaction chromatography, and gel-filtration chromatography.
- Ultrafiltration: The purity of an IgY preparation can be increased by combination; for example, PEG precipitation can be combined with affinity chromatography.
Services at Creative Biolabs
Creative Biolabs has been working on antibodies over years and we have also thrown our sights on non-IgG antibodies. The importance of non-IgG antibodies is self-evident, including IgY. With years of experience focusing on this field, Creative Biolabs has established a comprehensive platform offering a variety of non-IgG relevant services to global clients. IgY production and purification is one of what we are good at.
If you are interested in IgY production and purification, or you have any other questions about non-IgG antibodies, please don't hesitate to contact us for more information.
- Thirumalai, D.; et al. Chicken egg yolk antibody (IgY) as diagnostics and therapeutics in parasitic infections - A review. Int J Biol Macromol. 2019, 136: 755-763.
- Leiva, C. L.; et al. IgY-technology (egg yolk antibodies) in human medicine: A review of patents and clinical trials. Int Immunopharmacol. 2020, 81: 106269.
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