Researchers in the United Kingdom have discovered a human gene that prevents most bird flu viruses from infecting people. The work was published in the journal Nature .
Bird flu spreads mainly among wild birds such as ducks and seagulls, and farmed and free-range birds such as chickens, turkeys and quail. Although viruses primarily affect birds, they can spread to their predators and, rarely, to humans who are usually in close contact with infected animals.
Now, a team from the MRC-University of Glasgow Center for Virus Research studied hundreds of genes normally expressed by human cells, comparing the behavior of the genes during infection with human seasonal viruses or avian flu viruses.
They focused on a gene called BTN3A3 , which is expressed in both the upper and lower airways. Dubbed B-force by researchers, the gene blocks most strains of bird flu from replicating in human cells. This gene is part of a broader defensive apparatus in the human immune arsenal against avian viruses.
However, the antiviral activity of the gene failed to protect against seasonal human flu viruses, a Reuters news agency report indicated .
According to the researchers, all human flu pandemics, including that of 1918-19, were caused by flu viruses resistant to BTN3A3, so this gene appears to be a key factor in determining whether a bird flu strain has human pandemic potential.
To be sure, viruses mutate constantly, which does not mean that avian flu viruses cannot evolve to escape the activity of BTN3A3. Earlier this year, a new H5N1 strain of bird flu that spreads easily among wild birds spread widely to new corners of the planet, infecting and killing various species of mammals and raising fears of a pandemic in people. So far, only a handful of human cases have been reported to the World Health Organization (WHO).
Around 50% of the H5N1 strains circulating in the world until 2023 are resistant to BTN3A3, says Professor Massimo Palmarini, corresponding author of the study published in the scientific journal Nature .
"These are the kinds of things we should pay special attention to as an elevated risk level," added Sam Wilson, co-senior author of the study.
