Researchers have made significant progress in understanding the human gene that plays a crucial role in protecting individuals against most bird flu viruses.

Bird flu primarily affects wild birds, including ducks and gulls and can also infect farmed birds and domestic poultry such as chickens, turkeys and quails. While these viruses predominantly impact birds, there have been cases of transmission to bird predators and, rarely, to humans who have close contact with infected birds, according to Reuters.

A team of scientists from the MRC-University of Glasgow Centre for Virus Research conducted a study focusing on hundreds of genes expressed by human cells. By analyzing the behavior of these genes during infection with either human seasonal viruses or avian flu viruses, they identified a gene called BTN3A3 as a key player.

BTN3A3 is expressed in both the upper and lower respiratory tracts of humans and has earned the nickname "B-force" from the researchers. It was found to hinder the replication of most strains of bird flu in human cells.

Published in the journal Nature, the research revealed that BTN3A3 becomes active in the nose, throat and lungs, effectively reducing the ability of bird flu viruses to replicate. However, the gene's antiviral activity does not offer protection against seasonal human flu viruses.

Dr. Rute Maria Pinto, one of the researchers, said via BBC that "nearly all" bird flu strains are unable to bypass this protection, preventing them from jumping to humans. She added that the majority of human viruses, including all pandemic viruses to date, are resistant to BTN3A3, allowing them to overcome this block and infect humans.

The BTN3A3 gene is part of a broader defensive mechanism within the human immune system against bird viruses. The researchers noted that all human influenza pandemics, including the 1918-19 global flu pandemic, were caused by influenza viruses that were resistant to BTN3A3. Thus, the presence of this gene appears to be a crucial factor in determining the potential for any bird flu strain to cause a human pandemic.

It is important to note that viruses constantly mutate, and this discovery does not guarantee that bird flu viruses cannot evolve to evade the activity of BTN3A3. Earlier this year, a new bird flu strain emerged, demonstrating increased transmission among wild birds and raising concerns about a potential human pandemic.

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While only a few human cases have been reported thus far, approximately 50% of H5N1 strains circulating globally in 2023 are resistant to BTN3A3, according to Professor Massimo Palmarini, the corresponding author of the study, Reuters reported.

The study's co-senior author, Sam Wilson, emphasized the need to closely monitor this elevated level of risk associated with bird flu viruses. Understanding the protective mechanisms offered by genes like BTN3A3 is crucial for developing effective strategies to prevent and control potential outbreaks in the future.