National Avian Research Facility
National Avian Research Facility

DDX4 KO surrogate host

Genetically sterile female surrogate host chicken

DDX4 KO chicks
DDX4 knockout chicks

Summary & Utility

The female sterile surrogate host chicken provides a major advance for the creation of genetically altered chicken lines and the preservation of rare breeds. The DDX4 KO line is a genetically sterile female line1, that can transmit 100% of offspring from donor female primordial germ cells (PGCs)2. Therefore, the DDX4 KO line can produce offspring from genetically altered PGCs or PGCs from other breeds of chicken. Woodcock et al. (2019) have shown that by injecting PGCs from a heritage breed of Vantress chicken into DDX4 KO female embryos, all the offspring produced by these DDX4 females were derived from the donor heritage breed. Subsequent, artificial insemination of the DDX4 KO female surrogate host with frozen Vantress semen produced several pure heritage breed chicks2.


Line origin

The creation of the DDX4 KO line was led by Dr Mike McGrew and funded by BBSRC. The line was generated at the Roslin Institute and originally described in Taylor et al. (2017). TALE nucleases (TALENs) constructed by Recombinetics Inc, were used to target a reporter construct (GFP) to the DDX4 (vasa) locus in chicken PGCs and ablate DDX4 protein expression. Vasa is a key germ cell determinant in many animal species. Using a single TALEN pair, genetic deletions of the entire DDX4 locus in PGCs were created. The targeted PGCs were used to produce DDX4 knockout female chickens. In DDX4 knockout chickens, PGCs are initially formed but are lost during meiosis in the developing ovary, leading to adult female sterility.


For publications please reference; Taylor, L. et al. Efficient TALEN-mediated gene targeting of chicken primordial germ cells. Development, 144 (5), 928-934 (2017).



  1. Taylor, L. et al. Efficient TALEN-mediated gene targeting of chicken primordial germ cells. Development 144.5, 928–934 (2017).
  2. Woodcock, M. E. et al. Reviving rare chicken breeds using genetically engineered sterility in surrogate host birds. Proc. Natl. Acad. Sci. U. S. A. 116, 20930–20937 (2019).