As the H7N9 avian influenza outbreak in China grows, global leaders are becoming increasing concerned that the deadly flu virus could mutate into a pandemic.
The disease has already infected at least 133 people and killed 37 of those. It's not yet known whether the disease can spread from person to person or solely through contact with animals. Most of the infected have reported a history of exposure to chickens, but studies have shown that H7N9 can pass between ferrets under certain conditions.
Relatively little is known about why certain strains of bird flu spread more easily to humans than others, but two new studies in the journal Cell may help researchers and health officials better monitor the outbreak of these diseases and develop more effective vaccines against them.
Ram Sasisekharan of the Singapore-MIT Alliance for Research and Technology and his team analyzed the structure of the H5N1 and H7N9 viruses, particularly looking at hemagglutinin (HA)--a type of viral protein that binds to cell receptors in the respiratory tract of hosts.
They categorized the set of HA mutations needed to increase the infectivity of H5N1 and H7N9 viruses through improved binding to receptors in the human respiratory tract and found that only a single amino acid change in the HA sequence is necessary for this to occur. They also discovered that distinct HA mutations are evolving in the H7N9 virus, an indication that current vaccines would be ineffective at fighting new H7 strains.
There is no vaccine on the market for the lethal H7N9 strain.
Knowing which mutations spread more easily among humans could enhance the ability of scientists and health departments to find treatments for and monitor bird flu outbreaks.
- see the study abstracts here and here
- read the press release