User:Viroguy/sandbox

Marseilleviridae sandbox

Marseilleviridae is a family of viruses first named in 2012. The genomes of these viruses contain almost 500 genes in approximately 340–390 kilo base pairs (kbp) of double-stranded DNA packaged into icosahedral virions of approximately 200 to 250 nm diameter. For comparison, the smallest naturally occurring organism that can grow in pure culture (Mycoplasma genitalium} has about the same number of genes, and the smallest obligate endosymbiont bacterium, Nasuia deltocephalinicola has only approximately 140 protein coding genes and a 140 kbp genome. Amoeba are often hosts for marseilleviridae, but there is evidence that they are found in humans as well.    As of 2016, the International Committee on Taxonomy of Viruses (ICTV) recognizes four species in this family, divided among 2 genera.  However, there are alternate classifications based on DNA sequence data. The marseilleviridae are members of the nucleocytoplasmic large DNA viruses (NCLDV) clade.



ICTV Taxonomy
Group: dsDNA Order: Unassigned

Family: Marseilleviridae


 * Marseillevirus marseillevirus
 * Senegalvirus marseillevirus


 * Lausannevirus
 * Tunisvirus

Four lineage taxonomy


The four lineages, A, B, C and D and the viral species grouped into them are as follows.
 * Lineage A
 * Cannes8 virus
 * Marseillevirus (same as 2016 ICTV genus)
 * Melbourne virus
 * Senegalvirus (similar to 2016 ICTV classification)
 * Lineage B
 * Lausannevirus (2016 ICTV genus unassigned)
 * Lineage C
 * Insectomime
 * Tunisvirus (2016 ICTV genus unassigned)
 * Lineage D
 * Brazilian Marseillevirus

The viruses
In alphabetical order

Brazilian Marseillevirus
Is the first Marseillevirus from the Americas. It grows in Acanthamoeba castellanii, has 362,276 base pairs (bp) in the circular DNA genome and has almost 500 open reading frames (ORFs).

Cannes 8 virus
Was isolated from a cooling tower in Cannes, France by culturing the water sample with Acanthamoeba castellanii. Its circular genome has 374,041 bp and has almost 500 ORFs.

Insectomime
Was isolated from internal organs of a rat-tailed maggot of the drone fly Eristalis tenax found in a stagnant water reservoir tank. The discoverers discussed the possibility that the virus was either ingested directly or with a "Trojan horse" amoeba. The virus was grown by culturing with Acanthamoeba polyphaga. The icosahedral virus has a diameter of 225 nm with 386,631 bp of DNA.

Lausannevirus
Was isolated from an ameoba collected from the Seine river in 2005 It has only been found to grow in Acanthamoeba. The circular DNA sequence of 346,754 bp has been published, but a linear form with terminal repeats was also reported. Lausannevirus and marseillevirus share 3 genes that encode histone-like proteins and a few inteins among the approximately 90% protein similarity between the viruses.

Marseillevirus
Was isolated in 2009 from a cooling tower in Paris by culturing on Acanthamoeba polyphaga

Related Viruses
Additional species have since been recognized. The first member of this family recognized has been named Acanthamoeba polyphaga marseillevirus. A second member is Acanthamoeba castellanii lausannevirus. Two additional viruses have been isolated but have yet to be named. Another member of this family has been isolated from blood donors.

The viruses appear to fall into at least 3 lineages: (1) Marseillevirus and Cannes8virus (2) Insectomime and Tunisvirus and (3) Lausannevirus. A sixth potential member of this family—Melbournevirus—appears to be related to the Marseillevirus/Cannes8virus clade.

A seventh virus—Brazilian Marseillevirus—has been reported. This virus appears to belong to a fourth lineage of virus in this family.

Another virus—Tokyovirus—has also been reported.

Another member of this family is Kurlavirus.

Structure
Viruses in Marseilleviridae have icosahedral geometries. The diameter is around 250 nm. Genomes are circular, around 372kb in length. The genome has 457 open reading frames.

Life cycle
Dna templated transcription is the method of transcription. Amoeba serve as the natural host.

History
One of the first members of this family was described in 2009. Other members described around then (2007) and since then have been documented.