A unique viral strain deemed Pandoravirus was discovered that spans a staggering 1 µm in diameter, beating the previous record holder by two-fold. The viral giant also possesses the largest viral genome ever discovered, most of which cannot be traced back to any of the existing domains of life.

Just when we thought we had most of microbiology figured out, a team of French scientists isolated two colossal viruses with no apparent relatives, the first off the coast of Chile and the second from a freshwater pond in Melbourne, Australia. But even more bizarre than their sizes are their enormous genomes (2,5 Mb and 1,9 Mb) which resemble those of bacteria.

The amphora-like shape of the novel viruses, along with their mysterious origin inspired the founders to name them Pandoravirus salinus and Pandoravirus dulci after Pandora´s box, stating that “Opening the box will definitively break the foundations of what we thought viruses were”.

Many subsequent attempts have been made to classify the origin of the Pandoravirus genus with relatively little success. Roughly 93% of their genome corresponds to nothing known, however their DNA polymerase does share a close resemblance with those of other giant virsues (e.g. Megavirus), suggesting the existence of a controversial fourth domain of life.

Whatever the case may be, it´s definitely a sound reminder that our understanding of microbial life is far from comprehensive and that more mysteries likely lie ahead.

Watch the short video bellow to find out more about the newly-discovered giants!



By Luka Zupančič, MSc, University of Applied Sciences Technikum Vienna