Just five mutations could make the deadly H5N1 avian influenza into a pandemic virus, controversial research on ferrets suggests.
Since it first appeared widely in humans in 2003, the H5N1 virus has infected more than 650 people in 15 countries, killing nearly 60 percent of them. So far, it doesn’t pass easily from human to human.
A minimum of five genetic alterations are needed to make the bird flu into a virus that can infect ferrets — lab stand-ins for people — through the air, report Ron Fouchier of the Erasmus Medical Center in Rotterdam, the Netherlands, and colleagues in the April 10 Cell. Previous work by Fouchier’s and another group led, because of fears of misuse of research, to a temporary hold on publication of two scientific papers and a year-long moratorium on research that transforms bird viruses into airborne germs capable of infecting mammals (SN: 6/2/12, p. 20).
The new study shows that in order to spread via air between ferrets, the virus required changes to both its replication machinery and to the protein it uses to latch onto cells in the animals’ respiratory tract.
These five changes aren’t the only ones that could turn H5N1 into a pandemic virus, but may tell researchers the types of mutations they should look out for.