is found in birds, and it is being isolated for biotechnological applications from egg-yolk of chicken eggs. Studies have suggested that is functionally similar to IgG, and also shares some similarity with IgE. That means, similarly to IgGand presumably the main function of IgYis the defence against pathogens by binding them and thereby disabling them. However, in contrast to , IgYdoes not bind to protein A or protein G. Due to the functional similarities to , IgYis sometimes referred to as "chicken ", or "bird ."
Although IgYand IgGshare a similar function, they differ markedly in structure and immunochemical properties. Similarly to , IgYis composed of two heavy chains and two light chains, however, with a molecular mass of 180 kDa, the molecular weight of IgY is larger than that of mammalian IgG (150 kDa). The H-chain of IgYhas a larger molecular mass (68 kDa) than that of IgG (50 kDa).
IgY Antibodies in Biotechnology
For bioanlaytical experiments, IgY offers various advantages in comparison to mammalian antibodies. The yield of IgY from a chicken egg is comparable to that of IgG from rabbit serum however as hens produce new eggs on a daily basis the total yield is much higher. The (egg) yolk can be harvested without harming the animal. Of the immunoglobulins arising during the immune response, only IgY is found in chicken eggs. Thus, in preparations from chicken eggs, there is no contamination with Immunoglobulin A (IgA) or Immunoglobulin M (IgM). Addtionally the predicted cross-reactivity of IgY with proteins from mammals is lower.
Particularly in Asian countries, IgY has been clinically tested as a food supplement and preservative. For example, yogurt products containing pathogen specific IgY, have been tested for their ability to reduce Helicobacter pylori in the stomach by hindering the attachment of the bacterial to the stomach lining.