Since the latest reports of the new bird flu strain, H7N9, have brought the new infection total in China to 21, out of which 6 have already died, a recent study offers clues to the genetics of the more familiar H5N1 bird flu virus and how it could enable researchers to develop a vaccine against new strains.
“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,” said Wendy Barclay, lead author and professor in the department of medicine at Imperial College London.
The Avian Influenza A viruses such as H5N1 generally do not infect humans, according to the Centers for Disease Control and Prevention, however because of its potential to alter itself it’s become a risk for people to handle infected poultry. But the H7N9 strain seen in China was more transmittable from birds to people and it’s not life-threatening to poultry as it is to people-making it tougher to track.
The H5 and H7 could both be highly pathogenic after contact with dead or sick poultry, the difference is that H7 includes symptoms of conjunctivitis and respiratory problems.
According to the World Health Organization, there are no vaccines for the H7N9 subtype but it is susceptible to neuraminidase inhibitors, which stops the neuraminidase enzyme of influenza virus. The Chinese government has been keeping a close watch on the 530 other people who have since come into contact with the infected patients. Revelations to the H5N1 virus’ genetics could expose a vaccine that could stop new strains from forming and spreading among people.
The genetic findings appear in the Journal of General Virology. Researchers found that mutations in a protein called the H5 haemagglutinin, which binds the virus to a cell, allowed it to endure more acidic environments. Ultimately, these viruses could replicate more and spread from animal to animal.
“The studies published last year pointed to a mechanism that restricts replication of H5N1 viruses in the nose,” Barclay said. “We’ve engineered a different mutation with the same effect into one of the virus proteins and achieved a similar outcome. This suggests that there is a common mechanism by which bird flu could evolve to spread between humans, but that a number of different specific mutations might mediate that.”
When it comes to producing an effective virus, researchers feel that live attenuated flu vaccines would be best in pandemic conditions, because it can be manufactured more efficiently than the killed virus.
“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.