Medusavirus is a

nucleocytoplasmic large DNA virus ''Nucleocytoviricota'' is a phylum of viruses. Members of the phylum are also known as the nucleocytoplasmic large DNA viruses (NCLDV), which serves as the basis of the name of the phylum with the suffix - for virus phylum. These viruses are refe ...

first isolated from a

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

ese

hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ...

in 2019. It notably encodes all five types of

histone In biology, histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei. They act as spools around which DNA winds to create structural units called nucleosomes. Nucleosomes in turn are wr ...

s — H1, H2A, H2B, H3, and H4 — which are involved in DNA packaging in

eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

s, raising the possibility that they may have been involved in the

origin of eukaryotes Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bact ...

. The virus can harden

amoeba An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of Cell (biology), cell or unicellular organism with the ability to alter its shape, primarily by extending and ret ...

s of the species '' Acanthamoeba castellanii'' into stone-like

cyst A cyst is a closed sac, having a distinct envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac (like the manner in which ...

s, but infection usually causes infected amoebas to burst open. The virus was named after

Medusa In Greek mythology, Medusa (; Ancient Greek: Μέδουσα "guardian, protectress"), also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those ...

, the monster in

Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical co ...

whose gaze turned people to stone.

NCLD-viruses

Medusavirus is a part of a phylum called ''Nucleocytoviricota,'' which is referred as nucleocytoplasmic large DNA virus (NCLDV). These viruses has large double-stranded DNA genome and the length of the genome could be over than 100kb. NCLDV infects various eukaryotic hosts such as amoebas.

Morphology

Viral particle is composed of icosahedral capsid which is 260nm in diameter. This 8nm single layered capsid is covered with 14nm spherical-headed spikes. Viral double-stranded DNA is backed inside the 6nm thick internal membrane.

Maturation

Medusaviruses has unique viral particle maturation process comparing several other viruses. Virus does not form viral factory in the host cytoplasm to replicate the viral genome. The proposed maturation process starts by generating the pseudo- Empty viral particles with the help of scaffold proteins. Then these pseudo-Empty particles release the scaffold proteins and Empty particles are formed. After the release of proteins the Empty particle uptakes the viral DNA near the host nucleus and via semi-Full stages the Full particles are eventually formed.

References

DNA viruses Unaccepted virus taxa {{virus-stub