Chicks that don’t pass on bird flu

By Dr. Ananya Mandal, MDJan 13 2011

Influenza from birds, commonly known as H5N1 avian flu, has killed at least 306 people during the past seven years and innumerable birds and poultry. Now a team of scientists in Britain have developed a way to breed poultry that are genetically resistant to H5N1 or any other avian flu virus. The study by Scientists from Cambridge and Edinburgh universities was reported in the Jan. 13 issue of Science.

Helen Sang, a geneticist at the Roslin Institute at the University of Edinburgh and a co-author of the paper said, “Genetic modification could be more effective than vaccination… You wouldn’t need to change the way you tackle each disease.”

One of the initial steps was identification of a gene that could interfere with the replication of the avian flu virus. This was done by Lawrence Tiley, a molecular virologist at Cambridge University and the lead author of the paper. He identified a gene that could make birds produce a piece of RNA that acts as a decoy to polymerase, an enzyme that is vital for viral replication. Rather than binding with the virus’ genome, polymerase attaches itself to the decoy gene, preventing the virus from being able to replicate itself and spread. In the next step using Sang’s transgenic techniques, the team was able to insert the decoy gene into chick embryos.

Chicks born from these embryos were genetically modified or GM and when exposed to the avian flu, they were still infected, getting sick and eventually dying, but they did not pass on that virus to other chickens in close proximity, both transgenic birds and normal ones. Tiley said, “The transgenic birds that are infected are shedding virus that seems to be defective in some ways.”

Sang adds a word of caution adding, “Commercial success is a long way off.” She said these GM chickens would also need to be approved by regulators and accepted by consumers. The researchers are now planning to work on trying to make chickens that are fully resistant to bird flu rather than just blocking bird-to-bird transmission.