Genetically Modified Birds

 
4.4. Transgenic Birds For Erythropoietin Production 
Accordingly, it is an object of the present invention to provide a transgenic bird producing 
erythropoietin at high concentration levels as well as a method for constructing the same. The present inventors 
made intensive investigations and, as a result, found that a transgenic bird producing erythropoietin at high 
concentration levels can be obtained by the method which comprises incubating a fertilized avian egg, infecting 
the early embryo formed after egg laying, except for the blastoderm stage immediately following egg laying, 
with a replication-deficient retroviral vector containing a foreign erythropoietin gene and allowing the embryo 
to hatch. Such finding has now led to completion of the present invention. The bird to be used in the practice of 
the invention is not particularly restricted but includes those domestic fowls and pet birds which are reared for 
meat and egg production, for example chickens, turkeys, ducks, ostriches and quails. Among them, chickens and 
quails are preferred since they are readily available and are prolific layers.
The foreign erythropoietin gene to be used in the practice of the invention is not particularly restricted 
but preferably is a mammal-derived one, more specifically a human-derived one or one derived from a pet 
animal such as a dog, for instance. For expression thereof in avian cells, the foreign erythropoietin gene to be 
used in the practice of the invention is preferably connected to an appropriate promoter on the downstream side 
thereof.
 
4.5. Transgenic Birds For Bird Flu Resistance 
The long-term threat of an avian flu pandemic could be greatly reduced by a project to produce 
genetically modified chickens that can resist lethal strains of the virus. British scientists are genetically 
engineering chickens to protect them against the H5N1 virus that has devastated poultry farms in the Far East, 
with a view to replacing stocks with birds that are not susceptible to influenza. The technique should also offer 
protection against many other strains of flu with the potential to start a human pandemic, such as the H7 
subgroup that was responsible for an outbreak in Dutch poultry in 2003. If chicken populations were to be 
replaced with transgenic birds that were resistant to flu, it would remove a reservoir of the virus and make it 
much harder for it to spread to humans and trigger a pandemic. The team, led by Laurence Tiley, Professor of 
Molecular Virology at Cambridge University, and Helen Sang, of the Roslin Institute, near Edinburgh, has 
already shown that chicken cells can be protected against flu by inserting small pieces of genetic material. The 

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Genetically Modified Birds 
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researchers are now ready to begin a similar procedure with eggs and the first experiments are expected within 
weeks. Any breakthrough, however, will come too late to have an impact on the present outbreak of H5N1. 
Even if the technique works, it will be several years before it can be used to stock farms and it also faces 
important regulatory hurdles and a battle to win over public opinion. If these obstacles are overcome and 
farmers are willing to adopt GM chickens, the entire world stock could be replaced fairly quickly. “Once we 
have regulatory approval, we believe it will only take between four and five years to breed enough chickens to 
replace the entire world population,” Professor Tiley said. “Developing flu-resistant chickens has clear benefits 
for human health and animal welfare, as we wouldn‟t have to slaughter chickens around the world. Chickens 
provide a link between the wild bird population, where avian influenza thrives, and humans, where new 
pandemic strains can emerge. Removing that bridge will dramatically reduce the risk posed by avian viruses.” 
The research team is following three parallel approaches. One involves inserting a working copy of a gene that 
makes an antiviral protein called Mx, which is defective in many chicken breeds, and should improve their 
ability to fight off H5N1 and other strains. The second approach is to harness a technique called RNA 
interference, in which small fragments of the genetic signalling chemical RNA are used to disrupt the workings 
of the flu virus. By engineering chicken cells to make small RNA molecules that confuse the flu virus, the 
scientists hope to confer resistance to a wide variety of strains. The third strategy is similar to the second, but 
involves using RNA molecules as decoys, which trick the flu virus into copying them rather than itself. All three 
could potentially be incorporated in the same GM chickens.