Comparison of a Modern and Fossil Pithovirus Reveals Its Genetic Conservation and Evolution

International audience Most theories on viral evolution are speculative and lack fossil comparison. Here, we isolated a modern Pithovirus-like virus from sewage samples. This giant virus, named Pithovirus massiliensis, was compared with its prehistoric counterpart, Pithovirus sibericum, found in Sib...

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Bibliographic Details
Published in:Genome Biology and Evolution
Main Authors: Levasseur, Anthony, ANDREANI, JULIEN, Delerce, Jeremy, Khalil, Jacques Bou, Robert, Catherine, La Scola, Bernard, Raoult, Didier
Other Authors: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-IFR48, INSB-INSB-Centre National de la Recherche Scientifique (CNRS)
Format: Article in Journal/Newspaper
Language:English
Published: HAL CCSD 2016
Subjects:
[SDV.MHEP.MI]Life Sciences [q-bio]/Human health and pathology/Infectious diseases
permafrost
Online Access:https://hal.archives-ouvertes.fr/hal-01455587
https://doi.org/10.1093/gbe/evw153
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Summary:International audience Most theories on viral evolution are speculative and lack fossil comparison. Here, we isolated a modern Pithovirus-like virus from sewage samples. This giant virus, named Pithovirus massiliensis, was compared with its prehistoric counterpart, Pithovirus sibericum, found in Siberian permafrost. Our analysis revealed near-complete gene repertoire conservation, including horizontal gene transfer and ORFans. Furthermore, all orthologous genes evolved under strong purifying selection with a non-synonymous and synonymous ratio in the same range as the ratio found in the prokaryotic world. The comparison between fossil and modern Pithovirus species provided an estimation of the cadence of the molecular clock, reaching up to 3 x 10(-6) mutations/site/year. In addition, the strict conservation of HGTs and ORFans in P. massiliensis revealed the stablegenetic mosaicism in giant viruses and excludes the concept of a bag of genes. The genetic stability for 30,000 years of P. massiliensis demonstrates that giant viruses evolve similarly to prokaryotes by classical mechanisms of evolution, including selection and fixation of genes, followed by selective constraints.

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