A subtype of bird flu is rapidly mutating, posing risks to humans, British scientists have warned.
The virus is endemic in Chinese poultry farms – but an analysis of an infection in a human patient found multiple changes.
Some of the changes increased the severity of infections in animals whilst others seemed to make it increasingly transmissible by air.
Researchers at the University of Nottingham say the virus had acquired an ability to infect humans as well as to survive airborne transmission.
The Nottingham researchers worked with Chinese scientists on the project, studying a patient who suffered severe pneumonia. The findings were reported last night in the journal Cell.
The scientists say humans are likely to lack immune resistance to the H3N8 virus, even if vaccinated against H3N2 flu.
Researcher Professor Kin-Chow Chang said: “We demonstrate that an avian H3N8 virus isolated from a patient with severe pneumonia replicated efficiently in human bronchial and lung epithelial cells, was extremely harmful in its effects in laboratory mammalian hosts and could be passed on through respiratory droplets.
“Importantly, we discovered that the virus had acquired human receptor binding preference and amino acid substitution PB2-E627K, which are necessary for airborne transmission. Human populations, even when vaccinated against human H3N2 virus, appear immunologically naïve to emerging mammalian adapted H3N8 AIVs and could be vulnerable to infection at epidemic or pandemic proportion.”
Professor Chang added: “Acid resistance of influenza virus is also an important barrier for avian influenza virus to overcome to acquire the adaptability and transmissibility in new mammals or humans. The current novel H3N8 virus has not acquired the acid resistance yet. So, we should pay attention to the change on acid resistance of the novel H3N8 virus.”
Airborne transmission of human-isolated avian H3N8 influenza virus between ferrets. Cell 4 September 2023
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