A Refined Approach to Producing Polyclonal Antibodies in Chickens – Completely Replacing All Invasive Elements by Combining Immunizations with Routine Aerosol-based Vaccinations (finished project)

Otto Kalliokoski

The aim is to exploit routine vaccination of chickens, administered in aerosol form, to raise antibodies against a model immunogen (a protein) coupled to the surface of the vaccine’s virus particles. Combined with isolation/purification of antibodies from egg yolk, this method will not only reduce the number of animals needed in the production of polyclonal antibodies, but also completely eliminate the need of invasive procedures associated with conventional antibody production, thus constituting an immense refinement of methodology.

Our project vision was to devise and demonstrate a method for producing antibodies in hens without using invasive methods. By using hens instead of the commonly used mammalian models for antibody production – e.g. rabbits, mice, rats – we could circumvent the need for drawing large-volume blood samples, instead extracting antibodies from unfertilized eggs.

Moreover, hens are routinely vaccinated against respiratory tract viruses – specifically infectious bronchitis virus – using an inhaled aerosol of inactivated virus particles. If we, instead of injecting the hens with our immunogen – the template molecule we want to raise antibodies against – could “piggy-back” it onto the inactivated virus particles, we could immunize the animals while they are undergoing mandatory vaccinations.

This would remove the only remaining invasive procedure. Due to the large amounts of antibodies that can be obtained from an egg, the outlined approach has potential to reduce the use of laboratory animals. Removing the need to inject immunogens and draw blood constitutes a considerable refinement of procedures. Suffering could be entirely removed: There would be no need to break the skin with needles, no need for stressful restraint, no anemia, and no need for inflammation-potentiating adjuvants.

Globally, a considerable number of laboratory animals are used for the production of antibodies, and despite great advances in antibody-based methods, we will not replace the use of animals fully within a foreseeable future. Consequently, refining procedures and reducing the numbers of animals needed in antibody production can have a great impact for a number of years to come.

The support of the Danish 3R Center allowed us to develop all the technical procedures needed for the outlined proof-of-concept. The commercially available chicken vaccines are, however, of so poor a quality as to prevent us from demonstrating the approach in chickens at present. We have thus chosen to hold off on carrying out experiments on chickens. The chances of success are, currently, too low; this would simply constitute a pointless use of laboratory animals – something we are opposed to.

Moving forward, we will look into means for disseminating the methods we have developed and will keep looking for opportunities to obtain a better model vaccine capable of finally demonstrating our idea in full.

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