Mimiviridae: An Expanding Family of Highly Diverse Large dsDNA Viruses Infecting a Wide Phylogenetic Range of Aquatic Eukaryotes

Abstract

Since 1998, when Jim van Etten’s team initiated its characterization, Paramecium bursaria Chlorella virus 1 (PBCV-1) had been the largest known DNA virus, both in terms of particle size and genome complexity. In 2003, the Acanthamoeba-infecting Mimivirus unexpectedly superseded PBCV-1, opening the era of giant viruses, i.e., with virions large enough to be visible by light microscopy and genomes encoding more proteins than many bacteria. During the following 15 years, the isolation of many Mimivirus relatives has made Mimiviridae one of the largest and most diverse families of eukaryotic viruses, most of which have been isolated from aquatic environments. Metagenomic studies of various ecosystems (including soils) suggest that many more remain to be isolated. As Mimiviridae members are found to infect an increasing range of phytoplankton species, their taxonomic position compared to the traditional Phycodnaviridae (i.e., etymologically “algal viruses”) became a source of confusion in the literature. Following a quick historical review of the key discoveries that established the Mimiviridae family, we describe its current taxonomic structure and propose a set of operational criteria to help in the classification of future isolates.

Metagenomic analysis of virus diversity and relative abundance in a eutrophic freshwater harbour

“…Here we will use the term Mimiviridae to encompass the formally recognized Mimiviridae as well as the proposed ‘extended Mimiviridae ’ subfamily that are often considered phycodnaviruses. Proposed members of the ‘Mesomimivirinae’ include Organic Lake phycodnaviruses (OLPVs), Aureococcus anophageefferens virus (AaV), Chrysochromulina ericina virus (CeV), Phaeocystis pouchetii virus (PpV), Pyramimonas orientalis virus (PoV), and Group I Phaeocystis globosa viruses (PgVs) [39,41-44]. Based on these recent developments, we manually curated the affiliation of viruses that belong to the proposed Mesomimivirinae group but were annotated as Phycodnaviridae in the current NCBI scheme (accessed April 2018), as viruses within the Mimiviridae (Table S1).…”

The Old and the New on Viral Diseases in Sturgeon

“…This family includes a variety of large, double-stranded DNA viruses affecting eukaryotic organisms, mainly algae and protists. Should sNCLDV eventually be confirmed Mimiviridae, they will be first viruses in this family capable of infecting vertebrate organisms [45].…”

“…The only report of NV infection is by Clouthier and co-authors [20]. Other studies on NV focus mainly on the hypothesis that this and other sNCLDV belong to the Mimiviridae family [44,45,54].…”

Exploration of the propagation of transpovirons within Mimiviridae reveals a unique example of commensalism in the viral world

“…Giant viruses infect unicellular eukaryotes, some regulating the populations of bloom forming algae [14][15][16][17][18][19]. As of today, the Mimiviridae family appears composed of several distinct subfamilies [10,[15][16][17][18][20][21][22][23][24] one of which, the proposed Megamimivirinae [5,17,18], corresponds to the family members specifically infecting These authors contributed equally: Sandra Jeudy, Lionel Bertaux Acanthamoeba [20][21][22][23]. Members of this subfamilies, collectively refers to as "mimiviruses" throughout this article, can be infected by dsDNA satellite viruses called virophages only able to replicate using the already installed intracytoplasmic viral factory [16,[25][26][27][28].…”