Studies showing how bird flu viruses could adapt to humans offer surveillance and vaccine strategies

June 6, 2013

Bird flu viruses are potentially highly lethal and pose a global threat, but relatively little is known about why certain strains spread more easily to humans than others. Two studies published today in the journal Cell identify mutations that increase the infectivity of H5N1 and H7N9 viruses through improved binding to receptors in the human respiratory tract. The findings offer much-needed strategies for monitoring the emergence of dangerous bird flu strains capable of infecting humans and for developing more effective vaccines.

"Avian influenza viruses evolve rapidly, and there are many subtypes of these viruses that we need to be concerned about because, in many cases, humans do not have immunity to these newer strains," says senior study author Ram Sasisekharan of the Singapore-MIT Alliance for Research and Technology. "Our findings can be put to use to monitor the evolution of H5N1 and H7N9 viruses in the field as well as in the clinic if and when there is an outbreak."

In the past 10 years, the has infected nearly 600 individuals in several outbreaks around the world, killing about 60% of those infected. And over the past few months, a lethal subtype of the H7N9 virus has been found in at least 131 people, mostly in . Although these viruses do not normally infect humans, over time they can adapt to humans and gain the ability to spread more easily from person to person, underscoring the importance of finding out which mutations could enhance the ability of these viruses to infect humans.

To address this question, Sasisekharan and his team analyzed the structure of the H5N1 and H7N9 viruses, focusing on hemagglutinin (HA)—a type of that binds to in the respiratory tract of hosts. They characterized the set of HA mutations required to increase the preference of the viruses for human receptors, discovering that only a single amino acid change in the HA sequence is necessary for this to occur. Moreover, they found that distinct HA mutations are evolving in the H7N9 virus indicating that currently recommended H7 vaccines would not be effective against this newly emerged virus.

"Right now, there is no vaccine to protect against the H7N9 virus, and our findings could guide efforts to develop effective vaccine strategies," Sasisekharan says.

Explore further: Recent studies warn surveillance of bird flu strains is needed

More information: Tharakaraman et al.: "Glycan Receptor Binding of the Influenza A Virus H7N9 Hemagglutinin." Cell, dx.doi.org/10.1016/j.cell.2013.05.034

Tharakaraman et al.: "Structural Determinants for Naturally Evolving H5N1 Hemagglutinin to Switch its Receptor Specificity." Cell, dx.doi.org/10.1016/j.cell.2013.05.035

Related Stories

WHO says new H7N9 flu passes more easily from bird to human

April 24, 2013

A new strain of bird flu that emerged in China over the past month is one of the "most lethal" flu viruses so far, worrying health officials because it can jump more easily from birds to humans than the one that started killing ...

Recommended for you

Bile acid uptake inhibitor prevents NASH / fatty liver in mice

September 21, 2016

Drugs that interfere with bile acid recycling can prevent several aspects of NASH (nonalcoholic steatohepatitis) in mice fed a high-fat diet, scientists from Emory University School of Medicine and Children's Healthcare of ...

New therapeutic target for Crohn's disease

September 20, 2016

Research from the Sanford Burnham Prebys Medical Discovery Institute (SBP) identifies a promising new target for future drugs to treat inflammatory bowel disease (IBD). The study, published today in Cell Reports, also indicates ...

Mosquitoes, Zika and biotech regulation

September 19, 2016

In a new Policy Forum article in Science, NC State professor Jennifer Kuzma argues that federal authorities are missing an opportunity to revise outdated regulatory processes not fit for modern innovations in biotechnology, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.