Huge viruses may open 8216;Pandora8217;s8217; box: French study

Instead,what is most interesting about them is their giant-sized genome 8212; from 1,900 to 2,500 genes 8212; way more than viruses like influenza,which has 10. Humans,by comparison,have about 24,000.

The previous record for a virus was 1,200 genes,in the discovery of the Megavirus chilensis. Before that was the Mimivirus with around 1,000 genes,discovered by the same team of scientists a decade ago.

Viruses are typically not deemed to qualify as a form of life,but some scientists say these giant viruses merit consideration as a new kind of living object.

One,Pandoravirus salinus,was found on sediment off the coast of Las Cruces,Chile. The other,Pandoravirus dulcis,was found in the muck of a pond in Melbourne,Australia.They are visible under a light microscope and look to have more in common with cells than other known viruses.

Pandoraviruses come from a different family than previously known giant viruses,said researchers Jean-Michel Claverie,a professor at the school of medicine at Aix-Marseille University and Chantal Abergel,director of research at France8217;s National Center for Scientific Research CNRS.

Their container-like shape and unique set of genes 8220;made us associate them to the Pandora box. The opening of the box will definitively break the foundations of what we thought viruses were,8221; the researchers said.

Most of their genes appear unfamiliar to scientists,and they contain code for proteins and enzymes that 8220;do unknown things,8221; the authors said.

8220;The lack of similarity of most of their genes with other life forms might be an indication that they originated from a totally different primitive cellular lineage.8221;

That means,according to the researchers,that Pandoraviruses may come from a 8220;different tree of life altogether,8221; than the three domains of life known to science as bacteria,single-celled micro-organisms known as archaea,and eukarya which includes fungi,plants and animals.