French scientists find giant new virus
11th December 2009
SCIENTISTS in France have isolated a new giant virus that lurks inside
amoeba and whose gene pool includes genetic material from other
species.
The virus "is a completely new viral form," said Didier Raoult, head
of infectious and emerging tropical disease research at Aix-Marseille
2 University in France.
The genome of the so-called Marseillevirus encompasses a complex
repertoire of genes that are "very different from the DNA of other
virus forms," and shows that there is genetic exchange between other
micro-organisms such as giant viruses and bacteria found in amoeba, he
told AFP in an interview.
Amoeba, single-cell life forms that can be parasites on either human
or animals, are acting as "a sort of cradle of creation for new
viruses and bacteria," Raoult said, whose research was also published
this week by the Proceedings of National Academy of Sciences.
Only a small number of so-called giant viruses have been discovered,
the first in 1993 by accident. Unlike classic viruses, they can been
viewed through a conventional light microscope.
Even now little is known about them but in 2008, a team led by Raoult
even found viruses that infect other viruses so as to replicate
themselves, he said.
With a genome of 368,000 basic pairs, Marseillevirus is the fifth
biggest virus ever sequenced and has a diametre of 250 nanometres
(around 250 millionth of a millimetre, according the a report by
Raoult's for the French National Centre for Scientific Research
(CNRS).
The DNA of the giant virus contains material from different sources
including plant and animal matter, bacteria and other giant viruses
such as the Mimivirus, the report said.
"There is a mechanism of permanent creation going on in amoeba
producing a new repertoire of viruses and predisposing giant viruses
to become pathogens once they specialise", Raoult said.
He said the mechanism was not foreseen by Charles Darwin's theory that
life comes from a common ancestor.
"The idea of a common ancestor makes no sense in the light of
viruses," he said.
"That was Darwin's idea, but he was clearly wrong."
http://www.themorningbulletin.com.au/story/2009/12/11/french-scientists-find-giant-new-virus/