Researchers Find Biggest Viruses on Earth. They Have Named Them Pandoravirus

Posted on July 20, 2013


Mimiviruses, which are extremely large viruses, were discovered about ten years ago. The discovery prompted the scientific community to reconsider the upper limits of the viral world. Researchers have now discovered viruses even bigger than Mimiviruses. The monster viruses live underwater. They are reportedly about 1,000 times the size of influenza viruses.

Nadege Philippe and colleagues discovered these two even larger viruses underwater. Their findings are raising a whole new set of questions. The newly discovered viruses have been named Pandoraviruses. The researchers found one of the huge viruses, which they named Pandoravirus salinus, at the mouth of the Tunquen River in Chile. They found another monster virus, which they called Pandoravirus dulcis, at the bottom of a freshwater pond near Melbourne, Australia.

These two Pandoraviruses are about a full micrometer in size. They are larger than parasitic bacteria and they are visible with traditional light microscopy. Compared to Mimivirus genomes, which are approximately 1.0 mega base pair in size, they have respective genomes of 1.9 and 2.5 mega base pairs. The researchers say Pandoraviruses defy comparison to any other virus families and their origins cannot be traced back to any known lineage.

The research was reported in the journal, Science. NPR reports that despite the Pandora (as in Pandora's Box) name, the new viruses do not pose a major threat to human health.

Photos: Chantal Abergel / Jean-Michel Claverie