Bird-swine flu hybrid could be a killer combo

Bird flu is back on the radar, with the United Nations Food and Agriculture Organization (FAO) warning of a new mutant strain that is spreading amongst bird populations in Asia and beyond.

According to the FAO, this could lead to a resurgence of the H5N1 Highly Pathogenic Avian Influenza, which has already infected 565 people since 2003, and killed 331.

However, should such a strain of influenza happen to cross with the recent H1N1 ‘swine flu’ strain, it could morph into a serious threat, said Professor Peter Doherty, Laureate Professor at the University of Melbourne.

“The recent H1N1 ‘swine ‘flu’ pandemic was caused by the reassortment of genes from two pig viruses. That virus was incredibly infectious and went around the world in six months though, fortunately, it was not especially virulent as it took about six months before we started getting vaccine into peoples’ arms.

“If, however, a pig became infected simultaneously with an HP H5N1 virus and the 2009 pandemic strain, it is possible that an extremely virulent variant that spreads readily between humans could emerge,” he said.

Professor Doherty has spent a lifetime studying the immune system, and in 1996 he and Professor Rolf Zinkernagel received the Nobel Prize in Physiology or Medicine for their work uncovering the role of the Major Histocompatibility Complex in immunity.

Vaccination against individual strains is important, said Professor Doherty, although the virus has been able to mutate to get around vaccines targeted just as H5N1.

“Vaccination does not seem to be the solution, and it is thought that large chicken populations serve as ‘incubators’ for the selection of resistant mutants.

“Whether such mutants are indeed being spread by migratory water birds is less clear, though the pattern of sporadic re-introductions in remote locations is suggestive,” he said.

This raises the possibility of combating bird flu before it is able to infect humans, possibly by employing genetic modification of chickens.

“One high-tech solution that is being pursued in research laboratories is to engineer a spectrum of resistance/interference genes into domestic poultry. If that works, it could provide a solution though it would, of course, require that those in the affected regions overcome any qualms they might have concerning the consumption of GM chickens.”

According to Professor Doherty, another strategy to combating such pandemic outbreaks influenza before they have an opportunity to mutate is the development of a vaccine that acts as a prophylactic against multiple strains.

“That is one of the many reasons why the current, global effort to develop much more cross-reactive influenza vaccines for production ahead of time (perhaps as a strategic reserve) is so important.”

Bird flu first appeared in 2003 and reached a peak of public attention in 2005-2006, although since then it has largely disappeared from public consciousness. Even though infections and deaths have continued to occur since 2006, the volume of news reports has dropped to almost zero in the last 18 months, according to Google Insights.