Experimental fossilisation of viruses from extremophilic Archaea
- 1Centre de Biophysique Moléculaire, UPR4301, CNRS, Rue Charles Sadron, 45071 Orléans Cedex 2, France
- 2Observatoire des Sciences de l'Univers en région Centre, UMS3116, 1A Rue de la Férollerie, 45071 Orléans Cedex 2, France
- 3Université de Bretagne Occidentale, UMR 6539, CNRS – Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, Rue Dumont d'Urville, 29280 Plouzané, France
- 4Molecular Biology of the Gene in Extremophiles Unit, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
Abstract. The role of viruses at different stages of the origin of life has recently been reconsidered. It appears that viruses may have accompanied the earliest forms of life, allowing the transition from an RNA to a DNA world and possibly being involved in the shaping of tree of life in the three domains that we know presently. In addition, a large variety of viruses has been recently identified in extreme environments, hosted by extremophilic microorganisms, in ecosystems considered as analogues to those of the early Earth. Traces of life on the early Earth were preserved by the precipitation of silica on the organic structures. We present the results of the first experimental fossilisation by silica of viruses from extremophilic Archaea (SIRV2 – Sulfolobus islandicus rod-shaped virus 2, TPV1 – Thermococcus prieurii virus 1, and PAV1 – Pyrococcus abyssi virus 1). Our results confirm that viruses can be fossilised, with silica precipitating on the different viral structures (proteins, envelope) over several months in a manner similar to that of other experimentally and naturally fossilised microorganisms. This study thus suggests that viral remains or traces could be preserved in the rock record although their identification may be challenging due to the small size of the viral particles.