anti-Immunoglobulin Y (IgY) secondary antibodies

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 and presumably the main function of is the defence against pathogens by binding them and thereby disabling them. However, in contrast to , does not bind to protein A or protein G. Due to the functional similarities to , is sometimes referred to as "chicken ", or "bird ."

Although and share a similar function, they differ markedly in structure and immunochemical properties. Similarly to , is 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 has a larger molecular mass (68 kDa) than that of IgG (50 kDa).

Below you will find examples of anti- antibodies: