lili
December 18th, 2008, 03:15 AM
Infectiologie
Un virus à virus
Il y avait les bactériophages, des virus qui infectent les bactéries. Il y a maintenant les virophages : des virus qui infectent d’autres virus. Cette nouvelle catégorie de virus ne compte cependant pour l’instant qu’un seul membre, identifié par une équipe de chercheurs français (CNRS Aix-Marseille II).
Le virophage a été observé à l’intérieur d’un mimivirus, un virus géant qui infecte lui-même des amibes. L’équipe marseillaise l’a baptisé Spoutnik. Comme tous les virus, le virophage Spoutnik vampirise son hôte afin de se multiplier. Dans ce cas précis, il apparaît que la multiplication du virophage conduit à une inhibition de la réplication du mimivirus.
Une analyse du génome de Spoutnik a révélé la présence de gènes d’origine virale et de gènes de bactériophages. Les recherches imaginent que ce virus d’un nouveau type pourrait contribuer au transfert horizontal de gènes viraux.
› E. B.
B. La Scola et coll., « Nature », septembre 2008, vol. 455, pp. 100-104
Le Quotidien du Médecin du : 18/12/2008
http://www.quotimed.com/journal/index.cfm?fuseaction=viewarticle&DartIdx=421171
Letter
Nature 455, 100-104 (4 September 2008) | <abbr title="Digital Object Identifier">doi</abbr>:10.1038/nature07218; Received 16 June 2008; Accepted 27 June 2008; Published online 6 August 2008Article Links
The virophage as a unique parasite of the giant mimivirus
Bernard La Scola<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1),</sup><sup>6 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a6)</sup>, Christelle Desnues<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1),</sup><sup>6 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a6)</sup>, Isabelle Pagnier<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Catherine Robert<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Lina Barrassi<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Ghislain Fournous<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Michèle Merchat<sup>2 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a2)</sup>, Marie Suzan-Monti<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Patrick Forterre<sup>3 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a3),</sup><sup>4 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a4)</sup>, Eugene Koonin<sup>5 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a5)</sup> & Didier Raoult<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>
URMITE, Centre National de la Recherche Scientifique UMR IRD 6236, Faculté de Médecine, Université de la Méditerranée, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 5, France
Climespace, 185 Rue de Bercy, 75012 Paris, France
Biologie Moléculaire du Gène chez les Extrêmophiles, Institut de Génétique et Microbiologie, Bâtiment 409, Université Paris Sud, Centre d'Orsay, 91405 Orsay Cedex, France
Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
National Center for Biotechnology Information (NCBI), National Library of Medicine, National Institutes of Health, Building 38A, Room 5N503, 8600 Rockville Pike, Bethesda, Maryland 20894, USA
These authors contributed equally to this work.
Correspondence to: Didier Raoult<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup> Correspondence and requests for materials should be addressed to D.R. (Email: didier.raoult@gmail.com).
Top of page (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#top)Abstract
Viruses are obligate parasites of Eukarya, Archaea and Bacteria. Acanthamoeba polyphaga mimivirus (APMV) is the largest known virus; it grows only in amoeba and is visible under the optical microscope. Mimivirus possesses a 1,185-kilobase double-stranded linear chromosome whose coding capacity is greater than that of numerous bacteria and archaea<sup>1, (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B1)</sup><sup>2, (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B2)</sup><sup>3 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B3)</sup>. Here we describe an icosahedral small virus, Sputnik, 50 nm in size, found associated with a new strain of APMV. Sputnik cannot multiply in Acanthamoeba castellanii but grows rapidly, after an eclipse phase, in the giant virus factory found in amoebae co-infected with APMV<sup>4 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B4)</sup>. Sputnik growth is deleterious to APMV and results in the production of abortive forms and abnormal capsid assembly of the host virus. The Sputnik genome is an 18.343-kilobase circular double-stranded DNA and contains genes that are linked to viruses infecting each of the three domains of life Eukarya, Archaea and Bacteria. Of the 21 predicted protein-coding genes, eight encode proteins with detectable homologues, including three proteins apparently derived from APMV, a homologue of an archaeal virus integrase, a predicted primase–helicase, a packaging ATPase with homologues in bacteriophages and eukaryotic viruses, a distant homologue of bacterial insertion sequence transposase DNA-binding subunit, and a Zn-ribbon protein. The closest homologues of the last four of these proteins were detected in the Global Ocean Survey environmental data set<sup>5 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B5)</sup>, suggesting that Sputnik represents a currently unknown family of viruses. Considering its functional analogy with bacteriophages, we classify this virus as a virophage. The virophage could be a vehicle mediating lateral gene transfer between giant viruses.
http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html
<!-- generated by Nature-branded standard table template -->
Un virus à virus
Il y avait les bactériophages, des virus qui infectent les bactéries. Il y a maintenant les virophages : des virus qui infectent d’autres virus. Cette nouvelle catégorie de virus ne compte cependant pour l’instant qu’un seul membre, identifié par une équipe de chercheurs français (CNRS Aix-Marseille II).
Le virophage a été observé à l’intérieur d’un mimivirus, un virus géant qui infecte lui-même des amibes. L’équipe marseillaise l’a baptisé Spoutnik. Comme tous les virus, le virophage Spoutnik vampirise son hôte afin de se multiplier. Dans ce cas précis, il apparaît que la multiplication du virophage conduit à une inhibition de la réplication du mimivirus.
Une analyse du génome de Spoutnik a révélé la présence de gènes d’origine virale et de gènes de bactériophages. Les recherches imaginent que ce virus d’un nouveau type pourrait contribuer au transfert horizontal de gènes viraux.
› E. B.
B. La Scola et coll., « Nature », septembre 2008, vol. 455, pp. 100-104
Le Quotidien du Médecin du : 18/12/2008
http://www.quotimed.com/journal/index.cfm?fuseaction=viewarticle&DartIdx=421171
Letter
Nature 455, 100-104 (4 September 2008) | <abbr title="Digital Object Identifier">doi</abbr>:10.1038/nature07218; Received 16 June 2008; Accepted 27 June 2008; Published online 6 August 2008Article Links
The virophage as a unique parasite of the giant mimivirus
Bernard La Scola<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1),</sup><sup>6 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a6)</sup>, Christelle Desnues<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1),</sup><sup>6 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a6)</sup>, Isabelle Pagnier<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Catherine Robert<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Lina Barrassi<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Ghislain Fournous<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Michèle Merchat<sup>2 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a2)</sup>, Marie Suzan-Monti<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>, Patrick Forterre<sup>3 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a3),</sup><sup>4 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a4)</sup>, Eugene Koonin<sup>5 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a5)</sup> & Didier Raoult<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup>
URMITE, Centre National de la Recherche Scientifique UMR IRD 6236, Faculté de Médecine, Université de la Méditerranée, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 5, France
Climespace, 185 Rue de Bercy, 75012 Paris, France
Biologie Moléculaire du Gène chez les Extrêmophiles, Institut de Génétique et Microbiologie, Bâtiment 409, Université Paris Sud, Centre d'Orsay, 91405 Orsay Cedex, France
Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
National Center for Biotechnology Information (NCBI), National Library of Medicine, National Institutes of Health, Building 38A, Room 5N503, 8600 Rockville Pike, Bethesda, Maryland 20894, USA
These authors contributed equally to this work.
Correspondence to: Didier Raoult<sup>1 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#a1)</sup> Correspondence and requests for materials should be addressed to D.R. (Email: didier.raoult@gmail.com).
Top of page (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#top)Abstract
Viruses are obligate parasites of Eukarya, Archaea and Bacteria. Acanthamoeba polyphaga mimivirus (APMV) is the largest known virus; it grows only in amoeba and is visible under the optical microscope. Mimivirus possesses a 1,185-kilobase double-stranded linear chromosome whose coding capacity is greater than that of numerous bacteria and archaea<sup>1, (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B1)</sup><sup>2, (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B2)</sup><sup>3 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B3)</sup>. Here we describe an icosahedral small virus, Sputnik, 50 nm in size, found associated with a new strain of APMV. Sputnik cannot multiply in Acanthamoeba castellanii but grows rapidly, after an eclipse phase, in the giant virus factory found in amoebae co-infected with APMV<sup>4 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B4)</sup>. Sputnik growth is deleterious to APMV and results in the production of abortive forms and abnormal capsid assembly of the host virus. The Sputnik genome is an 18.343-kilobase circular double-stranded DNA and contains genes that are linked to viruses infecting each of the three domains of life Eukarya, Archaea and Bacteria. Of the 21 predicted protein-coding genes, eight encode proteins with detectable homologues, including three proteins apparently derived from APMV, a homologue of an archaeal virus integrase, a predicted primase–helicase, a packaging ATPase with homologues in bacteriophages and eukaryotic viruses, a distant homologue of bacterial insertion sequence transposase DNA-binding subunit, and a Zn-ribbon protein. The closest homologues of the last four of these proteins were detected in the Global Ocean Survey environmental data set<sup>5 (http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html#B5)</sup>, suggesting that Sputnik represents a currently unknown family of viruses. Considering its functional analogy with bacteriophages, we classify this virus as a virophage. The virophage could be a vehicle mediating lateral gene transfer between giant viruses.
http://www.nature.com/nature/journal/v455/n7209/full/nature07218.html
<!-- generated by Nature-branded standard table template -->