Advantages of Using Egg Yolk Antibodies in the Life Sciences: The Results of Five Studies

It has been known for over a century that specific antibodies can be extracted from the eggs of immunised chickens. However, it was only when animal welfare became a subject of public debate that the chicken was considered as an alternative source of antibodies due to the possibility of non-invasive antibody sampling. Unfortunately, the welfare of animals alone is not sufficient to attract the interest of scientists; it is therefore important to demonstrate to potential users that avian antibodies can be used successfully in a variety of scientific investigations. The particular specificity of avian antibodies would appear to be due to the phylogenetic difference between Mammalia and Aves as well as to differences between the molecular structures of avian immunoglobulin (IgY) and mammalian immunoglobulin (IgG). The use of avian antibodies has additional advantages, as a considerable quantity of antibodies can be obtained from one chicken, and because the specificity of avian antibodies often markedly differs from that of comparable mammalian antibodies. This paper aims to demonstrate the advantages of using avian antibodies by presenting the results of five separate studies. In the first study, coordinated by Rüdiger Schade, the visualisation of cholecystokinin-like immuno-reactivity in the substantia nigra of rats by using anti-cholecystokinin antibody, without the pre-treatment of colchicine, is described. The second study, headed by Albrecht Zott, describes the use of avian antibodies in the identification of modern acellular pertussis vaccines by using rocket immunoelectrophoresis. The identification of unknown vaccine batches and the comparison with reference vaccines is a prerequisite for reducing the number of animal experiments necessary for vaccine control. The third study, coordinated by Martin Gerl, investigates the specificity of antibodies directed against the N-terminal propeptide of procollagen type III (PIIINP). Among the antibodies originating from different species (rabbit, mouse and chicken), only the chicken antibody was able to respond to the PIIINP in both human and rat sera. Thus, a direct comparison between human serum samples (alcoholic liver) and serum samples derived from corresponding animal models was possible. The fourth study, coordinated by Michael Erhard, shows that egg yolk antibodies can be successfully used to manage infectious diarrhoea in young agricultural animals. The final study, led by Andreas Hlinak, describes the successful production of anti-bovine leukaemia virus antibody. This antibody could be used in several diagnostic systems (for example, enzyme immunoassays and cytology). The five studies demonstrate that avian antibodies are an attractive alternative to mammalian antibodies, not only with respect to the welfare of animals, but also with respect to scientific and economic considerations.