The recent H10N8 strain of bird flu is unlikely to result in a public health threat without further mutations in the virus that would allow it to spread between humans.
H10N8 is the latest in a line of continually evolving avian influenza viruses that can cause serious, potentially fatal disease in humans.
H10N8 was first detected in humans in December 2013. The virus was found in a 73-year-old woman from Nanchang City in China, after she was admitted to the hospital with symptoms of severe pneumonia and fever. She died 9 days after the onset of illness.
There have since been two further cases of the infection in humans, including one more death from the virus.
Earlier this year, a report in The Lancet warned of the potential of a pandemic, with experts writing:
"A H5N1 virus infection in Hong Kong in 1997 preceded the next 17 cases by 6 months, so more human cases of H10N8 infection might occur in the future. The pandemic potential of this novel virus should not be underestimated."
Assessing the binding properties of avian flu strains
At the Medical Research Council National Institute for Medical Research (MRC-NIMR), researchers have been investigating what potential the H10 family of viruses have for causing a pandemic.
The virus will need to change receptor binding preference for more efficient transmission to humans.
Assessing this requires the researchers to examine the molecular structure of the virus and see how it is able to bind to receptors.
The researchers found that the H10 viruses have the same binding characteristics of other pandemic flu strains, such as H1 (the 1918 Spanish flu). There are also similarities in binding properties between H10 and the H7 viruses that have infected humans.
Where the H10 deviates from the H1 and H7 viruses, though, is in its preference of receptor. H1 and H7 viruses bind up to 100 times more strongly to human receptors than avian receptors. However, the H10 viruses bind with avian receptors about 150 times more strongly than with human receptors.
"We pay special attention to viruses that show changes in receptor binding preference," says Dr. John McCauley, director of the World Health Organization (WHO) Influenza Centre at the MRC-NIMR, "because it is likely to be a requirement for more efficient transmission to humans."
"A change in receptor binding is the essential first step in generating a pandemic virus," asserts Dr. McCauley, who adds that the MRC-NIMR results illustrate "the sophisticated scientific basis of monitoring influenza viruses and the importance of the WHO global influenza surveillance for public health."
His colleague Prof. Paul Moss, chair of the MRC Infection and Immunity Board, says:
"Outbreaks and epidemics can strike quickly with a substantial impact on society. It is essential that we respond swiftly to potential pandemic strains. The team at the MRC-NIMR has been at the forefront of this endeavor and their work here shows exactly how the latest influenza virus identified from birds is able to bind to human cells. The work will be very important in allowing us to monitor for mutations that could lead to the virus gaining the ability to spread between humans."