Study of bird flu mutation offers vaccine clue

Scientists have found small genetic changes that enable the H5N1 bird flu virus to replicate more easily in the noses of mammals, which may help find a vaccine for the virus.

While there have only been isolated cases of bird flu in humans and no widespread transmissions, a new study shows that just a few mutations could allow the virus to easily spread between humans. The new findings could help develop better vaccines to fight the strains of bird flu that would be able to spread between humans.

"Knowing why bird flu struggles to replicate in the nose and understanding the genetic mutations that would enable it to happen are vital for monitoring viruses circulating in birds and preparing for an outbreak in humans," Wendy Barclay, from the Department of Medicine at Imperial College London and leader of the recent study, said.

Bird flu rarely infects humans because the human nose has different receptors compared to birds and is more acidic. The research showed that mutations in the virus could enable it to tolerate higher acid levels.

The results of the study could have important implications for making vaccines against pandemic strains of the H5N1. In the study, viruses with modified haemagglutinin proteins induced strong antibody responses in ferrets, which would mean vaccines with similar modifications could prove more effective than the ones previously tested.

"We can't predict how bird flu viruses will evolve in the wild, but the more we understand about the kinds of mutations that will enable them to transmit between humans, the better we can prepare for a possible pandemic," Barclay said.