In-depth study of Mollivirus sibericum , a new 30,000-y-old giant virus infecting Acanthamoeba

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Legendre, Matthieu, Lartigue, Audrey, Bertaux, Lionel, Jeudy, Sandra, Bartoli, Julia, Lescot, Magali, Alempic, Jean-Marie, Ramus, Claire, Bruley, Christophe, Labadie, Karine, Shmakova, Lyubov, Rivkina, Elizaveta, Coute, Yohann, Abergel, Chantal, Claverie, Jean-Michel
• Other Authors: Information génomique et structurale (IGS), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Biologie à Grande Échelle (BGE - UMR S1038), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Génomique d'Evry (IG), Université Paris-Saclay-Institut de Biologie François JACOB (JACOB), Institute of Physicochemical and Biological Problems in Soil Science, RAS, ANR-14-CE14-0023,Pandoravirus,Caractérisation fonctionnelle et moléculaire des Pandoravirus(2014), ANR-10-INBS-0008,ProFI,Infrastructure Française de Protéomique(2010), ANR-10-INBS-0009,France Génomique,Organisation et montée en puissance d'une Infrastructure Nationale de Génomique(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: [SDV]Life Sciences [q-bio]; permafrost
• Online Access: https://cea.hal.science/cea-01825900; https://doi.org/10.1073/pnas.1510795112

International audience Acanthamoeba species are infected by the largest known DNA viruses. These include icosahedral Mimiviruses, amphora-shaped Pandoraviruses, and Pithovirus sibericum, the latter one isolated from 30,000-y-old permafrost. Mollivirus sibericum, a fourth type of giant virus, was isolated from the same permafrost sample. Its approximately spherical virion (0.6-µm diameter) encloses a 651-kb GC-rich genome encoding 523 proteins of which 64% are ORFans; 16% have their closest homolog in Pandoraviruses and 10% in Acanthamoeba castellanii probably through horizontal gene transfer. The Mollivirus nucleocytoplasmic replication cycle was analyzed using a combination of “omic” approaches that revealed how the virus highjacks its host machinery to actively replicate. Surprisingly, the host’s ribosomal proteins are packaged in the virion. Metagenomic analysis of the permafrost sample uncovered the presence of both viruses, yet in very low amount. The fact that two different viruses retain their infectivity in prehistorical permafrost layers should be of concern in a context of global warming. Giant viruses’ diversity remains to be fully explored.