Medusavirus: Newly-Found Large Virus Turns Its Hosts into ‘Stone’


A workforce of researchers has remoted a brand new large virus from sizzling spring water in Japan. Named medusavirus, the virus infects a species of amoeba known as Acanthamoeba castellanii and may flip its host right into a stone-like cyst.

Cryo-EM image of a DNA-filled medusavirus particle viewed from a 3-fold axis; spike, capsid, and membrane are labeled. Scale bar - 100 nm. Image credit: Yoshikawa et al, doi: 10.1128/JVI.02130-18.

Cryo-EM picture of a DNA-filled medusavirus particle considered from a Three-fold axis; spike, capsid, and membrane are labeled. Scale bar – 100 nm. Picture credit score: Yoshikawa et al, doi: 10.1128/JVI.02130-18.

“Viruses are labeled primarily based on their genetic traits, that’s, by how they generate mRNA to provide proteins and genetic materials,” mentioned Professor Masaharu Takemura, a virologist on the Tokyo College of Science, and colleagues.

“Medusavirus is a nucleocytoplasmic massive DNA virus that belongs to a gaggle of not too long ago found eukaryotic viruses with massive and complicated double-stranded DNA genomes.”

Medusavirus, with a diameter of 260 nm, has a icosahedral capsid with distinctive spherical-headed spikes on its floor.

It’s the first large virus remoted from a heated surroundings (110 levels Fahrenheit, or 43.four levels Celsius), and it exhibits a number of distinctive options in its replication cycle and particle morphology.

Based mostly on the dissimilarities with different recognized large viruses, Professor Takemura and co-authors proposed that medusavirus represents a brand new viral household, Medusaviridae.

Medusavirus may help scientists better understand the origins of DNA replication and the evolution of complex life. Image credit: Tokyo University of Science.

Medusavirus could assist scientists higher perceive the origins of DNA replication and the evolution of complicated life. Picture credit score: Tokyo College of Science.

“Not like most viruses, medusavirus incorporates genes that encode for proteins concerned in DNA packaging,” the scientists mentioned.

“The virus has a full set of histones, that are proteins which have developed to maintain the DNA folded contained in the nucleus and regulate gene expression.”

“That is notably unusual, as we think about that viruses haven’t any nucleus. This might imply that in the course of the co-evolution, the virus might need acquired the genes that encode these histones.”

When medusavirus petrifies the Acanthamoeba castellanii amoeba, it does so by hijacking the cell immediately from its nucleus.

The virus transfers its DNA to provoke replication and makes use of its personal DNA polymerase (enzyme that synthesizes DNA) and histones, however total, it depends on the host to finish the method.

The outcomes of an evolutionary evaluation carried out by the researchers counsel that within the evolution tree, the medusavirus DNA polymerase lies on the origin of the DNA polymerase present in eukaryotes.

“This might imply that our DNA polymerase most likely originated from medusavirus or considered one of its kinfolk,” mentioned Dr. Genki Yoshikwa, a scientist at Kyoto College.

The invention is reported in a paper within the Journal of Virology.


G. Yoshikawa et al. 2019. Medusavirus, a novel massive DNA virus found from sizzling spring water. J Virol 93: e02130-18; doi: 10.1128/JVI.02130-18

Leave a Reply