Recent advances in precision genome engineering tools coupled with new approaches to generate transgenic chickens mean that we now have the ability to generate knockout, knock in or knock about chickens.
Breakthroughs in the generation of genetically engineered birds have come from the use of primordial germ cell (PGC) culture and more recently the development of direct injection technology and sperm transfection assisted gene editing (STAGE) which provide alternatives to establishing PGCs cultures. When these methods are coupled with precision genome engineering tools such as CRISPR we have the ability to make changes to the chicken genome which were previously very difficult to achieve. To date we have used this approach to target two endogenous genes and are currently in the process of screening G0 males. We have also used CRISPR in cultured PGCs to generate multiple gene knockout lines. These cultured PGCs can be injected in recipient embryos to generated edited birds.
Our lab has also had great success generating stable germline transgenic birds which express protein coding genes or RNAi molecules against both exogenous and endogenous targets. To generate these birds we used our direct injection method combined with miniTol2 transposons plasmids. The miniTol2 transposons plasmids are modified to contain the sequence of interest as well a marker gene to allow easy selection of the transgenic chickens.
We now have the ability to generate genetically engineered birds that can be used for a number of applications including improved production traits, bioreactors, disease models and for functional genomics studies.