Antarctica was long considered to be virtually free of pathogens. Today, however, a completely different picture is emerging: The White Continent is home to a surprisingly wide variety of viruses, many of which appear to have co-existed for a long time with penguins, seabirds and marine mammals without causing any discernible disease. However, the outbreak of the highly pathogenic H5N1 avian influenza in 2024 highlighted just how vulnerable this unique ecosystem is to newly introduced pathogens.
It was only modern molecular biological techniques such as PCR and genome sequencing that made it possible to chart the hidden viral world of Antarctica. Scientists discovered numerous adenoviruses, astroviruses, circoviruses and polyomaviruses, as well as deltacoronaviruses and several previously unknown viral lineages found exclusively in Antarctica. Research now shows that penguins harbour a similarly high diversity of RNA viruses to waterbirds in temperate latitudes. The supposed scarcity of viruses was therefore primarily due to a lack of research.
Researchers on the Antarctic Peninsula made a significant contribution to this new understanding with the discovery of the three previously unknown avulaviruses AAvV-17, AAvV-18 and AAvV-19. They were detected in Adélie, gentoo and chinstrap penguins and differ significantly from related viruses found in other regions of the world. As the infected animals showed no symptoms of disease and the viruses were present in several colonies, the scientists assume that they have long been part of the penguins’ natural virome.
Not all viruses are necessarily harmful. Some may even fulfil important functions for their hosts’ immune systems or ecological balance. However, the actual role played by the endemic viruses of Antarctica remains largely unexplored.
A turning point was the emergence of the highly pathogenic H5N1 avian influenza virus. Whilst no infections had been detected in 2023, the virus was first identified in skuas on James Ross Island in March 2024. Further findings further south confirmed that Antarctica has now become part of the global spread of this virus. Although no large-scale outbreaks have been observed in penguin colonies to date, the high population density of many breeding colonies makes the birds particularly vulnerable to highly contagious pathogens.
Research into Antarctic viruses is therefore becoming increasingly important. Climate change, increasing shipping traffic and a growing human presence are raising the risk that further pathogens will reach the isolated continent. At the same time, Antarctica offers a unique natural laboratory for studying the evolution of viruses and their interactions with their hosts. Continuous monitoring will be crucial to protecting the unique wildlife of the southernmost continent in the long term.
Rosamaria Kubny, PolarJournal