Newly discovered Medusavirus transforms amoebas into stone

If you're planning a Japanese vacation soon you might want to sit out the hot springs excursion, as scientists have recently discovered a strange virus in the medicinal waters of a regional natural hot tub that has some unsettling effects. Dubbed the "Medusavirus," it has the uncanny ability to transform a simple amoeba into a rigid shadow of its former self!

Jogging our memories of the dreaded Greek creature whose fatal stare turns mortals into solid stone, you'll recall that this ancient mythological monster named Medusa was a snake-haired Gorgon imbued with the debilitating power of instant petrification.

Fortunately for humans, Medusavirus belongs to a select sub-group called "giant viruses" which are known for their oversized genomes and only attack single-celled amoebas cataloged as Acanthamoeba castellanii. Extracted from the mud-streaked waters of a hot spring in Japan, the virus was introduced to amoebas in lab dishes, where the infecting organism caused the amoebas to develop a stone-like, hardened outer shell and immediately enter a dormant state known as encystment.

According to this new study by a group of researchers led by Genki Yoshikawa and Romain Blanc-Mathieu at the Institute for Chemical Research at Kyoto University and the Tokyo University of Science published Feb. 6 in the Journal of Virology, scientists encountered a unique feature on Medusavirus' outer surface in the form of more than 2,600 round-headed spike structures. Medusavirus is distinct enough from others found in the giant virus family that the team proposed that it should be classified into a new category: Medusaviridae.

"Medusavirus is a unique giant virus that still preserves the ancient footprints of the virus-host evolutionary interactions," the researchers explained in an official statement.  "Interestingly, a number of genes in Medusavirus were also found in its amoeba hosts. This suggest that Medusavirus has infected these amoebas since 'ancient times' and that the two microorganisms have exchanged genes over the course of evolution."

Why and how this newly found virus invades and alters its host is not readily known, and further tests are being conducted to learn more about its rigidifying properties. Until then, we'd advise staying out of any Japanese hot springs and sticking to the koi ponds and Buddhist temples while sightseeing instead, particularly if you're a single-celled amoeba!