Genome Editing: what impact for farm animal species?

Abstract

The advent of designer nucleases, especially CRISPR-Cas9, is providing a real breakthrough in genome editing technology. The principle is relatively simple. Double-strand breaks (DSB) are accurately produced on selected target DNA sequences from somatic, germinal, embryonic or iPS cells. These DSB are then repaired by non-homologous end-joining, resulting in inactivation (knock-out) of the targeted sequence(s), or by inserting a specific DNA fragment (template) through homologous recombination (knock-in). These technologies can be used in multiples domains, including fundamental research, gene therapy, ecological engineering, biotechnologies or agriculture. Many applications involving farm-animal species have already been published. Examples are presented of research projects aimed at improving animal health (acquisition of resistance to major infections and/or zoonotic diseases), avoiding controversial breeding practices (dehorning, elimination of male chicks), and improving the health impact (reduction of allergies) and/or nutritional values of animal products (milk, eggs, meat). Numerous questions raised by the use of CRISPR technology (techniques, regulation, economics, ethics…) are discussed.