World's biggest virus found in sea off Chile

A virus found in the sea off Chile is the biggest in the world, harbouring more than 1,000 genes.

The genome of Megavirus chilensis is 6.5 percent bigger than the DNA code of the previous virus record-holder, Mimivirus, isolated in 2003. M. chilensis is such a giant that it surpasses many bacteria in size and is genetically the most complex DNA virus ever described. It was taken from seawater sample closed to the shore of Las Cruces, Chile. Its host organism is unknown. 

DNA viruses include pox viruses and herpes viruses, but M. chilensis "doesn't seem to be harmful for humans," said Jean-Michel Claverie, of France's National Centre for Scientific Research (CNRS). Like all viruses, Megavirus reproduces by invading another cell and forcing it to produce new copies of the virus.

“In the grand order of things, these viruses exist to control amoeba populations” said Professor Barry, a virus expert from the University of Newcastle’s School of Biomedical Sciences and Pharmacy. 

“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.