|Aeron Hurt with a penguin.|
Credit: Aeron Hurt, WHO
Collaborating Centre for Reference
and Research on Influenza
The virus, found to be unlike any other circulating avian flu, is described in a study published this week in mBio®, the online open-access journal of the American Society for Microbiology.
Study author and Associate Professor Aeron Hurt, PhD, a senior research scientist at the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne, Australia, said that while other research groups have detected influenza antibodies in penguin blood samples, no one had detected actual live influenza virus in penguins or other birds in Antarctica before.
During January and February 2013, Hurt and his colleagues collected swabs from the windpipes and posterior (bottom) openings of 301 Adélie penguins, and blood from 270 of those penguins, in two locations on the Antarctic Peninsula.
The researchers found avian influenza virus (AIV) genetic material in eight (2.7%) samples – six from adult penguins and two from chicks. They were able to culture four of these viruses, showing that live infectious virus was present. Further analysis of the samples showed that all viruses were H11N2 influenza viruses that were highly similar to each other.
But when the researchers compared the full genome sequences of four of the collected viruses to all available animal and human influenza virus sequences in public databases, they made an interesting discovery.
Hurt said, “We found that this virus was unlike anything else detected in the world ... all of the genes were highly distinct from contemporary AIVs circulating in other continents in either the Northern or Southern Hemisphere.”
Using a molecular clock, the researchers estimated that the virus has been evolving for the past 49 to 80 years without anyone knowing about it. Hurt said that currently they did not know whether this evolution has occurred exclusively in Antarctica.
Additional experiments found that 16% of the penguins had influenza A antibodies in their blood, and that the newly identified virus is likely to affect only birds.
While the virus did not cause illness in the penguins, Hurt said the study shows that avian influenza viruses can get down to Antarctica and be maintained in penguin populations.
“It raises a lot of unanswered questions,” he said. These questions include: How often are AIVs being introduced into Antarctica? Is it possible for highly pathogenic (disease-causing) AIVs to be transferred there? What animals or ecosystems are maintaining the virus? Are the viruses are being cryopreserved during the winters?
The fieldwork was funded by the Instituto Antártico Chileno (Chilean Antarctic Institute) and the analysis was conducted at the WHO Collaborating Centre for Reference and Research on Influenza, which is supported by the Australian Government Department of Health.
Distinct avian influenza viruses found in Antarctic penguins [press release], 6 May 2014, American Society for Microbiology
Hurt AC, Vijaykrishna D, Butler J, Baas C, Maurer-Stroh S, Silva-de-la-Fuente MC, Medina-Vogel G, Olsen B, Kelso A, Barr IG, González-Acuña D. 2014. Detection of evolutionarily distinct avian influenza A viruses in Antarctica. mBio 5(3):e01098-14. doi:10.1128/mBio.01098-14.