09-09-2011, 06:36 PM
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| |Like a plot from a horror film, there’s a virus that brainwashes caterpillars, forces them to march up trees, then turns them to goo.
Now scientists at Penn State University have found the single gene that enables the virus to carry out its dark deeds.
The caterpillars would normally return to the ground to hide after feeding on leaves, but the baculovirus reprogrammes them to stay in the trees, melts them, then drips down among the remains to infect more of the creatures.
Researcher Kelli Hoover, writing in Science, said: ‘When gypsy moth caterpillars are healthy and happy, they go up into the trees at night to feed on leaves, and then climb back down in the morning to hide from predators during the day.
‘When they are infected, as they get sicker they stay up in the trees and die up there.’
He added: ‘There are other genes in the virus that then make the caterpillar melt. So it becomes a pool of millions of virus particles that end up dropping onto the foliage below where it can infect other moths that eat those leaves.’
His team discovered that the gene responsible for controlling the caterpillar is called egt.
In tests they were able to stop the zombie effect by removing the gene from the virus.
Another researcher on the team, Dr. Jim Slavicek, added: ‘Who knew that a virus could change the behavior of its host? Maybe this is why we go to work when we have a cold.’
Caterpillars aren’t the only creatures that become zombiefied by a virus.
Scientists discovered that the fungus Ophiocordyceps camponoti-balzani infects ant brains and forces them to infect other ants.
This is achieved by ‘programming’ the ant to hang off a leaf or twig near an ant nest while its brain is eaten by the parasite.
Shortly afterwards, spores from the body drop to the floor and infect other ants.