World’s largest virus found in Chile

The world’s largest virus has been found in seawater off the coast of Chile, measuring around 10 to 20 times the length of most viruses.

Named Megavirus chilensis, the giant virus infects single-cell marine amoebas and is slightly bigger than the virus previously known as the world’s biggest, Mimivirus, which was found in a water tower in the UK city of Bradford in 1992.

Professor Jean-Michel Claverie from Aix-Marseille University in France, who was part of the team that made the discovery and authored a paper on it in the journal PNAS, told the BBC that Megavirus was bigger than some bacteria.

“You don’t need an electron microscope to see it; you can see it with an ordinary light microscope,” he said.

Conjoint Professor Richard Barry, a virus expert from the University of Newcastle’s School of Biomedical Sciences and Pharmacy, said the fact that Megavirus could be seen with a light microscope was particularly significant.

“That used to be one of the defining features of a virus – that it was too small to be seen,” said Professor Barry, who was not involved in the discovery.

Like all viruses, Megavirus reproduces by invading another cell and forcing it to produce new copies of the virus.

“It may ecologically have an important role to play, in the sense that most ecological systems have checks and balances built into them,” said Professory Barry.

“In the grand order of things, these viruses exist to control amoeba populations.”

“I think it’s a very interesting discovery,” he said, adding that it was no surprise that the virus had been found in a marine environment.

“Over the last 20 to 30 years, there have been an ever increasing number of viruses found in fish,” he said.