According to a recent study by experts in China and Nottingham, a subtype of avian flu virus that is widespread in poultry farms in China is undergoing mutational alterations, which might raise the likelihood of the disease being transmitted to people.
The findings also raise worries about a potential epidemic or pandemic in the making, and researchers suggest that further study is needed to closely monitor such viruses in poultry and humans.
The findings, published in Cell, describe the characterisation of a human isolate of the H3N8 avian influenza virus (AIV) from a human patient. Using laboratory mice and ferrets as human infection models, the researchers discovered that the virus had undergone many adaptive alterations, causing severe animal illnesses and making it transmissible between animals via the airborne route.
In humans, avian H3N8 virus infection has been linked to acute respiratory distress syndrome, which can be lethal. The virus is common in chicken flocks; however, the characteristics of how it may be transferred from animals to people were previously unknown.
“We show 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 laboratory mammalian hosts, and could be passed on through respiratory droplets,” says University of Nottingham Professor Kin-Chow Chang.
“We discovered that the virus had acquired human receptor binding preference and the amino acid substitution PB2-E627K, both of which are required for airborne transmission.” Human populations remain immunologically naive to new mammalian-adapted H3N8 AIVs, even when vaccinated against human H3N2 virus, and might be susceptible to infection at epidemic or pandemic proportions.
“Influenza virus acid resistance is also an important barrier for avian influenza virus to overcome in order to acquire adaptability and transmissibility in new mammals or humans.” The current new H3N8 virus has not yet developed acid resistance. “As a result, we should keep an eye on the novel H3N8 virus’s acid resistance,” says Professor Jinhua Liu of China Agricultural University in Beijing.
The study was a partnership between the University of Nottingham, China Agricultural University in Beijing, the Chinese Academy of Sciences, and the Chinese Center for Disease Control and Prevention. It was named “Airborne transmission of human-isolated avian H3N8 influenza virus between ferrets.”