A multidisciplinary team of molecular biologists and veterinarians in the UK have developed a transgenic chicken which expresses RNA which inhibits and blocks the polymerase enzyme of the influenza virus, which is critical to replication. On exposure, transgenic birds were fully susceptible to challenge but subsequent shedding of virus to conventional contacts was prevented.
The significance of this work lies more in determining the mechanisms of infection and interaction of host cells and viral pathogens. The prospect of applying transgenic modification in breeding commercial poultry strains is at best speculative.
Genetic modification
Consumer resistance to genetic modification is evident and a number of years ago the major poultry breeders signed a pact confirming that molecular biology would be confined to identifying strains with desirable genetic characteristics without application or commercialization of genetic modification.
The performance of genetic modified strains would also be required to be superior to existing products with respect to commercial parameters.
Pandemic risk has not materialized
During the past five years, highly pathogenic avian influenza has been controlled by a combination of biosecurity and vaccination in most countries where H5N1 avian influenza is endemic. Commercial production continues to be minimally affected while subsistence operations involved in live bird sales are impacted by HPAI which can be regarded as the Newcastle disease of the 2000s.
The dire predictions that H5N1 avian influenza would become the next human pandemic have not materialized. In certain countries, including Egypt, sporadic cases of human H5N1 infection occur but these are usually associated with close proximity to infected flocks and contact with their blood and organs and may involve individuals with genetic susceptibility.
Mutations of the H5N1 virus to become pathogenic to human populations have not materialized and in retrospect the risks were highly overstated during the 2002-2003 following emergence of the infection in migratory birds and poultry flocks.
