Genes make H7N9 nimble killer, study finds
Researchers are worried the bird flu strain could one day become a 'doomsday virus' capable of human-to-human infection
A deadly bird-flu strain first reported among humans two years ago is a swift transformer loaded with more genetic ammunition than previously thought, a mainland study reveals.
Researchers found that much of the virus' deadly power came from within, and at least half of its six internal genes are capable of causing illness in humans.
They also found that H7N9 changed rapidly after finding a new host. In some cases mutations that helped it survive better in mammals appeared in just four days, enabling the virus to spread quickly and inflict more damage inside the new host.
The study, by a team at the Chinese Academy of Sciences' Key Laboratory of Pathogenic Microbiology and Immunology, was published in the Journal of Virology late last year.
Dr. Bi Yuhai, first author of the paper and the laboratory's technical director for flu virus, said H7N9 was probably the most elusive avian flu virus that scientists had encountered.
Since its emergence early in 2013, several key questions remain unanswered, including why it causes so few symptoms in birds - making early detection extremely difficult - and why it is so lethally active in humans. So far, at least 175 of about 460 people known to have been infected with the virus have died.