“This is an important study and adds to our broader understanding of the complexities of the hemagglutinin and neuraminidase mutations,” said Michael Osterholm, PhD, MPH, director of the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP), who wasn’t involved in the study.
“However, it doesn’t necessarily predict that this virus is close to becoming a human-to-human– transmitted virus,” he added. “There are likely other mutations we don’t yet understand that will be important in combination as relates to the emergence of a pandemic strain.”
With a growing number of H5N1 human infections resulting from contact with infected animals, the results highlight the importance of genomic surveillance to monitor for the emergence of H5N1 mutations, the authors said.
“Monitoring changes in receptor specificity (the way a virus recognizes host cells) is crucial because receptor binding is a key step toward transmissibility,” says Ian Wilson, DPhil, co-senior author and the Hansen Professor of Structural Biology at Scripps Research, in a Scripps news release. “That being said, receptor mutations alone don’t guarantee that the virus will transmit between humans.”
Flu viruses can mutate rapidly
In expert reaction published in the Science Media Centre, Ed Hutchinson, PhD, of the Medical Research Council-University of Glasgow Centre for Virus Research, said the findings are concerning because influenza viruses can mutate and evolve rapidly.
“For example, recent studies of the influenza viruses in a Canadian teenager, who has been severely ill for a prolonged period with H5N1 bird flu, implied that the virus had begun to evolve to ‘explore’ ways of binding more effectively to the cells in their body during the course of an infection,” said Hutchinson, who wasn’t involved with the study.
Ian Brown, PhD, OBE, Thomas Peacock, PhD, and Prof Munir Iqbal, MPhil, PhD, influenza researchers with the Pirbright Institute, added, “It must be stressed that the introduced mutations have not been detected to date in the H5 virus as it naturally transmits between cattle and spills over to avian and mammalian hosts … As the authors acknowledge, the switch in binding preference is one of several barriers the virus must overcome before it can acquire strong affinity to infect humans and spread between [them].”
