WASHINGTON, May 6 (Xinhua) -- A new version of bird flu known as H11N2 has been found in a group of Adelie penguins in Antarctica, an international team of researchers said Tuesday.
The virus was unlike any other circulating bird flu in the world, the team reported in mBio, the online open-access journal of the American Society for Microbiology.
While previous studies have detected influenza antibodies in penguin blood samples, this is the first time scientists have detected actual live influenza virus in penguins or other birds in Antarctica, study author Aeron Hurt, senior research scientist at the World Health Organization Collaborating Center for Reference and Research on Influenza in Melbourne, Australia, said in a statement.
The newly identified virus, however, did not cause illness in the penguins, and may be exclusive to birds, Hurt said. In a test to see if the virus could infect mammals, it failed to get a group of ferrets sick.
For the study, Hurt and colleagues collected swabs from the windpipes and posterior openings of 301 Adelie penguins, and blood from 270 of those penguins, from two locations on the Antarctic Peninsula: Admiralty Bay and Rada Covadonga. The samples were collected during January and February 2013.
The researchers found avian influenza viruses in eight samples, six from adult penguins and two from chicks.
On further analysis of the samples, the researchers found all viruses were H11N2 influenza viruses that were highly similar to each other.
But when the researchers compared the genome sequences of four of the collected viruses to all available animal and human influenza virus sequences in public databases, "we found that this virus was unlike anything else detected in the world," said Hurt.
"When we drew phylogenetic trees to show the evolutionary relationships of the virus, all of the genes were highly distinct from contemporary AIVs (avian influenza viruses) circulating in other continents in either the Northern or Southern Hemisphere."
Four of the gene segments were most closely related to North American avian lineage viruses from the 1960s to 1980s, while two genes showed a distant relationship to a large number of South American avian influenza viruses from Chile, Argentina and Brazil, the researchers said
Hurt estimated that the virus has been evolving for the past 49 to 80 years without anyone knowing about it, but whether this evolution has occurred exclusively in Antarctica is currently unknown.
"It raises a lot of unanswered questions," including how often bird flu viruses are being introduced into Antarctica, whether it is possible for highly pathogenic bird flu viruses to be transferred there, what animals or ecosystems are maintaining the virus, and whether the viruses are being cryopreserved during the winters, Hurt noted.