New research has found a key human gene responsible for blocking most avian flu viruses from spilling over into people.
The international study into the pandemic potential of avian flu, which is led by scientists at the MRC-University of Glasgow Centre for Virus Research (CVR), identified the human gene BTN3A3, which is commonly expressed in our airways, as a key human defence against avian flu.
Through a series of extensive tests, the study team were able to show that the BTN3A3 gene is vital to protecting humans against avian flu, as most strains of the virus cannot get past its defences. In contrast, seasonal human flu viruses, which infect the human population regularly, are resistant to BTN3A3.
Professor Massimo Palmarini, Director of CVR, who also led this study, said: “We know that most emerging viruses with human pandemic potential come from animals. It is therefore critical to understand which genetic barriers might block an animal virus from replicating in human cells, thereby preventing infection.
“Of course, viruses are constantly changing and can potentially overcome some of these barriers by mutating over time. This is why virus genetic surveillance will be crucial to help us better understand and control the spread of viruses with zoonotic and pandemic potential.”
Mutated strains of avian flu
The team also looked at avian flu viruses that occasionally do infect humans, for example H7N9, which since 2013 has infected more than 1,500 individuals with 40% case fatality rate. Researchers were able to show that avian flu viruses like H7N9 have a genetic mutation that allows them to ‘escape’ the blocking effects of the BTN3A3 gene.
Finally, the scientists were able to show that there had been increase in the number of BTN3A3-resistant strains circulating in poultry around the same time as spill over events in humans.
Dr Rute Maria Pinto, the first author of this study, said: “Identifying BTN3A3 resistant variants when they first emerge in birds might help prevent human infections. Control measures against emerging avian flu viruses can be tailored specifically against those that are BTN3A3-resistant, in addition to other genetic traits known to be important for zoonotic transmission.”