''Mimiviridae'' is a family of

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almo ...

Amoeba An amoeba (; less commonly spelled ameba or amœba; : amoebas (less commonly, amebas) or amoebae (amebae) ), often called an amoeboid, is a type of Cell (biology), cell or unicellular organism with the ability to alter its shape, primarily by ...

and other

protists A protist ( ) or protoctist is any Eukaryote, eukaryotic organism that is not an animal, Embryophyte, land plant, or fungus. Protists do not form a Clade, natural group, or clade, but are a Paraphyly, paraphyletic grouping of all descendants o ...

serve as natural hosts. The family contains three subfamilies that contain nine genera., UCPMS ID: 1889607
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/ref> Fig. 4 and §Discussion: "Considering that tupanviruses comprise a sister group to amoebal mimiviruses..." Viruses in this family belong to the

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 ...

clade (NCLDV), also referred to as

giant viruses A giant virus, sometimes referred to as a girus, is a very large virus, some of which are larger than typical bacteria. All known giant viruses belong to the phylum '' Nucleocytoviricota''. Description While the exact criteria as defined in the s ...

History

The first member of this family, Mimivirus, was discovered in 2003, and the first complete genome sequence was published in 2004. However, the mimivirus

Cafeteria roenbergensis virus ''Cafeteria roenbergensis'' virus (CroV), scientific name ''Rheavirus sinusmexicani'', is a giant virus that infects the marine bicosoecid flagellate ''Cafeteria roenbergensis'', a member of the microzooplankton community. History The virus was ...

was isolated and partially characterized in 1995, although the host was misidentified at the time, and the virus was designated BV-PW1.

Taxonomy

The family contains the following subfamilies and genera (-''virinae'' denotes subfamily and -''virus'' denotes genus): * '' Aliimimivirinae'' ** '' Rheavirus'' * '' Klosneuvirinae'' ** '' Fadolivirus'' ** '' Theiavirus'' ** '' Yasminevirus'' * '' Megamimivirinae'' ** '' Cotonvirus'' ** ''

Megavirus ''Megavirus'' is a viral genus, phylogenetically related to '' Acanthamoeba polyphaga mimivirus'' (APMV). In colloquial speech, ''Megavirus chilense'' is more commonly referred to as just "Megavirus". Until the discovery of pandoraviruses in 2 ...

'' ** ''

Mimivirus ''Mimivirus'' is a genus of giant viruses, in the family ''Mimiviridae''. It is believed that Amoeba serve as their natural hosts. It also refers to a group of phylogenetically related large viruses. In colloquial speech, APMV is more commonly ...

'' ** '' Moumouvirus'' ** ''

Tupanvirus ''Tupanvirus'' is a genus of viruses first described in 2018. The genus is composed of two species of virus that are in the giant virus group. Researchers discovered the first isolate in 2012 from deep water sediment samples taken at 3,000 m ...

Structure

Viruses in ''Mimiviridae'' have icosahedral and round geometries, with between T=972 and T=1141, or T=1200 symmetry. The diameter is around 400 nm, with a length of 125 nm. Genomes are linear and non-segmented, around 1200kb in length. The genome has 911 open reading frames.

Life cycle

Replication follows the DNA strand displacement model. DNA-templated transcription is the method of transcription. Amoeba serve as the natural host.

Molecular biology

Three putative DNA

base excision repair Base excision repair (BER) is a cellular mechanism, studied in the fields of biochemistry and genetics, that repairs damaged DNA throughout the cell cycle. It is responsible primarily for removing small, non-helix-distorting base lesions from t ...

enzymes were characterized from Mimivirus.Lad SB, Upadhyay M, Thorat P, Nair D, Moseley GW, Srivastava S, Pradeepkumar PI, Kondabagil K. Biochemical Reconstitution of the Mimiviral Base Excision Repair Pathway. J Mol Biol. 2023 Sep 1;435(17):168188. doi: 10.1016/j.jmb.2023.168188. Epub 2023 Jun 26. PMID 37380013 The base excision repair (BER) pathway was experimentally reconstituted using the purified recombinant proteins

uracil-DNA glycosylase Uracil-DNA glycosylase (also known as UNG or UDG) is an enzyme. Its most important function is to prevent mutagenesis by eliminating uracil from DNA molecules by cleaving the N-glycosidic bond and initiating the base-excision repair (BER) pathway ...

(mvUDG),

AP endonuclease Apurinic/apyrimidinic (AP) endonuclease is an enzyme that is involved in the DNA base excision repair pathway (BER). Its main role in the repair of damaged or mismatched nucleotides in DNA is to create a nick in the phosphodiester backbone of t ...

(mvAPE), and

DNA polymerase A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create t ...

X protein (mvPolX). When reconstituted in vitro mvUDG, mvAPE and mvPolX function cohesively to repair uracil-containing DNA predominantly by long patch base excision repair, and thus these processes likely participate in the BER pathway early in the Mimivirus life cycle.

Clinical

Mimiviruses have been associated with pneumonia but their significance is currently unknown. The only virus of this family isolated from a human to date is LBA 111. At the Pasteur Institute of Iran (Tehran), researchers identified mimivirus DNA in bronchoalveolar lavage (BAL) and sputum samples of a child patient, utilizing real-time PCR (2018). Analysis reported 99% homology of LBA111, lineage C of the ''Megavirus chilensis''. With only a few reported cases previous to this finding, the legitimacy of the mimivirus as an emerging infectious disease in humans remains controversial. ''Mimivirus'' has also been implicated in

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and h ...

References

External links

Viralzone: Mimiviridae

ICTV
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