Scientists sound alarm over mutating avian flu virus in China, raising pandemic concerns

Raising concerns of a potential epidemic or pandemic in the making, scientists have discovered a subtype of avian flu virus, endemic in poultry farms in China undergoing mutational changes, which could increase the risk of the disease being passed on to humans.

Published this week in the research journal Cell, the study focuses on characterising the H3N8 avian influenza virus (AIV) isolated from a human patient. Using laboratory mice and ferrets as human infection models, the research reveals significant adaptive changes in the virus, allowing it to cause severe animal infections and become airborne-transmissible between animals.

“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,” said Professor Kin-Chow Chang, at the University of Nottingham.

“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,” said Chang.

Titled “Airborne transmission of human-isolated avian H3N8 influenza virus between ferrets”, the study was a collaborative effort between the University of Nottingham, China Agricultural University in Beijing, the Chinese Academy of Sciences, and the Chinese Center for Disease Control and Prevention.

In humans, avian H3N8 virus infection has been linked to acute respiratory distress syndrome and even fatalities. While the virus is prevalent in chicken flocks, the precise mechanisms of its transmission to humans have remained poorly understood.

“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,” said Chang.