First Isolation of Mimivirus in a Patient With Pneumonia

Saadi, Hanene; Pagnier, Isabelle; Colson, Philippe; Chérif, J.; Beji, Mohammed; Boughalmi, Mondher; Azza, Saı̈d; Armstrong, Nicholas; Robert, Caroline; Fournous, Ghislain; Scola, Bernard La; Raoult, Didier

doi:10.1093/cid/cit354

Cited by 121 publications

(119 citation statements)

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“…Because these giant viruses are resistant to killing by phagocytic protists, we hypothesized that they may also reproduce in macrophages and might therefore infect humans. This proposition was validated experimentally by the isolation of mimivirus from atypical pneumonia patients and by the detection of marseilleviruses in blood donors and in human lymph nodes (7)(8)(9). Moreover, we and others identified sequences associated with giant viruses in metagenomes generated from human tissues, suggesting that giant viruses are a component of the human virome (10).…”

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confidence: 65%

Faustovirus, an Asfarvirus-Related New Lineage of Giant Viruses Infecting Amoebae

Reteno

Benamar

Khalil

et al. 2015

J Virol

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Giant viruses are protist-associated viruses belonging to the proposed order Megavirales; almost all have been isolated from Acanthamoeba spp. Their isolation in humans suggests that they are part of the human virome. Using a high-throughput strategy to isolate new giant viruses from their original protozoan hosts, we obtained eight isolates of a new giant viral lineage from Vermamoeba vermiformis, the most common free-living protist found in human environments. This new lineage was proposed to be the faustovirus lineage. The prototype member, faustovirus E12, forms icosahedral virions of Ϸ200 nm that are devoid of fibrils and that encapsidate a 466-kbp genome encoding 451 predicted proteins. Of these, 164 are found in the virion. Phylogenetic analysis of the core viral genes showed that faustovirus is distantly related to the mammalian pathogen African swine fever virus, but it encodes Ϸ3 times more mosaic gene complements. About two-thirds of these genes do not show significant similarity to genes encoding any known proteins. These findings show that expanding the panel of protists to discover new giant viruses is a fruitful strategy. IMPORTANCEBy using Vermamoeba, a protist living in humans and their environment, we isolated eight strains of a new giant virus that we named faustovirus. The genomes of these strains were sequenced, and their sequences showed that faustoviruses are related to but different from the vertebrate pathogen African swine fever virus (ASFV), which belongs to the family Asfarviridae. Moreover, the faustovirus gene repertoire is Ϸ3 times larger than that of ASFV and comprises approximately two-thirds ORFans (open reading frames [ORFs] with no detectable homology to other ORFs in a database). G iant viruses were first described in 2003, with the discovery of Acanthamoeba polyphaga mimivirus (1, 2). They are protistassociated viruses that belong to a major monophyletic group of double-stranded DNA (dsDNA) viruses known as nucleocytoplasmic large DNA viruses (NCLDVs), and they have been classified under the proposed order Megavirales (3). Since the first description of Acanthamoeba polyphaga mimivirus, giant viruses have been isolated from other phagocytic protists, primarily Acanthamoeba spp. (4-6). Because these giant viruses are resistant to killing by phagocytic protists, we hypothesized that they may also reproduce in macrophages and might therefore infect humans. This proposition was validated experimentally by the isolation of mimivirus from atypical pneumonia patients and by the detection of marseilleviruses in blood donors and in human lymph nodes (7-9). Moreover, we and others identified sequences associated with giant viruses in metagenomes generated from human tissues, suggesting that giant viruses are a component of the human virome (10). Because the investigation of a virome typically starts with a filtration procedure that eliminates giant viruses (11), we developed a new culture approach that does not prevent the detection of these viruses.In the present study, we de...

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confidence: 65%

Faustovirus, an Asfarvirus-Related New Lineage of Giant Viruses Infecting Amoebae

Reteno

Benamar

Khalil

et al. 2015

J Virol

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177

233

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“…Independently of the sugar that first interacted with the mimivirus particles, attachment to any sugar prevents interaction of the viral particles with other molecules, because the fibrils are completely saturated by the carbohydrate. Mimiviruses have already been isolated from distinct animals, such as the Shan virus and the LBA111 virus from humans (25,26), Hirudovirus from the invertebrate Hirudo medicinalis (27), and some viruses that have not yet been characterized from oysters (28). Furthermore, it has already been demonstrated that mimiviruses circulate among nonhuman mammals (29).…”

Section: Discussionmentioning

confidence: 99%

Mimivirus Fibrils Are Important for Viral Attachment to the Microbial World by a Diverse Glycoside Interaction Repertoire

Rodrigues

Silva

Dornas

et al. 2015

J Virol

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Acanthamoeba polyphaga mimivirus (APMV) is a giant virus from the Mimiviridae family. It has many unusual features, such as a pseudoicosahedral capsid that presents a starfish shape in one of its vertices, through which the ϳ1.2-Mb double-stranded DNA is released. It also has a dense glycoprotein fibril layer covering the capsid that has not yet been functionally characterized. Here, we verified that although these structures are not essential for viral replication, they are truly necessary for viral adhesion to amoebae, its natural host. In the absence of fibrils, APMV had a significantly lower level of attachment to the Acanthamoeba castellanii surface. This adhesion is mediated by glycans, specifically, mannose and N-acetylglucosamine (a monomer of chitin and peptidoglycan), both of which are largely distributed in nature as structural components of several organisms. Indeed, APMV was able to attach to different organisms, such as Gram-positive bacteria, fungi, and arthropods, but not to Gram-negative bacteria. This prompted us to predict that (i) arthropods, mainly insects, might act as mimivirus dispersers and (ii) by attaching to other microorganisms, APMV could be ingested by amoebae, leading to the successful production of viral progeny. To date, this mechanism has never been described in the virosphere. IMPORTANCEAPMV is a giant virus that is both genetically and structurally complex. Its size is similar to that of small bacteria, and it replicates inside amoebae. The viral capsid is covered by a dense glycoprotein fibril layer, but its function has remained unknown, until now. We found that the fibrils are not essential for mimivirus replication but that they are truly necessary for viral adhesion to the cell surface. This interaction is mediated by glycans, mainly N-acetylglucosamine. We also verified that APMV is able to attach to bacteria, fungi, and arthropods. This indicates that insects might act as mimivirus dispersers and that adhesion to other microorganisms could facilitate viral ingestion by amoebae, a mechanism never before described in the virosphere.

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“…Moreover, the first giant virus isolated from a patient sample was a member of the Marseilleviridae, called senegalvirus, which was isolated from a stool sample of an asymptomatic patient from Senegal (154,292). Later, the first human virus of the Mimiviridae, LBA111, was isolated from a pulmonary sample (293). Finally, a last giant virus of the Mimiviridae, called Shan virus, was isolated from a stool sample of a patient presenting with pulmonary disease (294).…”

Section: Fig 3 Amoeba Culturing Methods For Recovering Amoeba-resistimentioning

confidence: 99%

Current and Past Strategies for Bacterial Culture in Clinical Microbiology

et al. 2015

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SUMMARY A pure bacterial culture remains essential for the study of its virulence, its antibiotic susceptibility, and its genome sequence in order to facilitate the understanding and treatment of caused diseases. The first culture conditions empirically varied incubation time, nutrients, atmosphere, and temperature; culture was then gradually abandoned in favor of molecular methods. The rebirth of culture in clinical microbiology was prompted by microbiologists specializing in intracellular bacteria. The shell vial procedure allowed the culture of new species of Rickettsia . The design of axenic media for growing fastidious bacteria such as Tropheryma whipplei and Coxiella burnetii and the ability of amoebal coculture to discover new bacteria constituted major advances. Strong efforts associating optimized culture media, detection methods, and a microaerophilic atmosphere allowed a dramatic decrease of the time of Mycobacterium tuberculosis culture. The use of a new versatile medium allowed an extension of the repertoire of archaea. Finally, to optimize the culture of anaerobes in routine bacteriology laboratories, the addition of antioxidants in culture media under an aerobic atmosphere allowed the growth of strictly anaerobic species. Nevertheless, among usual bacterial pathogens, the development of axenic media for the culture of Treponema pallidum or Mycobacterium leprae remains an important challenge that the patience and innovations of cultivators will enable them to overcome.

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First Isolation of Mimivirus in a Patient With Pneumonia

Cited by 121 publications

References 30 publications

Faustovirus, an Asfarvirus-Related New Lineage of Giant Viruses Infecting Amoebae

Faustovirus, an Asfarvirus-Related New Lineage of Giant Viruses Infecting Amoebae

Mimivirus Fibrils Are Important for Viral Attachment to the Microbial World by a Diverse Glycoside Interaction Repertoire

Current and Past Strategies for Bacterial Culture in Clinical Microbiology

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