Descripción del proyecto
Trayectoria evolutiva de virus gigantes en el mundo celular
Los «Mimivirus» (de la familia «Mimiviridae») son virus icosaédricos gigantes visibles a través del microscopio óptico y que usan las amebas como hospedador natural. El descubrimiento de estos y otros virus gigantes ha planteado preguntas sobre su origen y evolución. El proyecto financiado con fondos europeos VIREVOL investigará la coevolución de estos virus y sus amebas hospedadoras centrándose en características específicas de los viriones. La hipótesis del estudio es que se produjo una transición de los viriones icosaédricos rígidos a las partículas más plásticas con forma de ánfora a través del secuestro de la ruta de síntesis de la celulosa del hospedador por parte del antepasado de estos virus. La investigación también se centrará en la estructura con forma de barra y en la organización de su genoma para desvelar los vínculos evolutivos con los sistemas de empaquetado del genoma en el mundo celular.
Objetivo
The discovery of Mimivirus, the first icosahedral virus visible by light microscopy, was followed by the characterization of many other relatives. Its aquatic relative Megavirus chilensis, has a 1.2 Mb genome and encodes more than 1000 proteins, 2/3 unique to the Mimiviridae. Their infectious cycle is cytoplasmic. During the last 10 years, my laboratory discovered three other giant virus families: -the pandoraviridae, with their unique amphora-shaped 1µm long virion morphologies, genome sizes reaching 3Mb and encoding thousands of proteins, most of which without homologues in the cellular or the viral world – the mollivirus, which was isolated from a 30,000 years old Siberian permafrost sample, presents common features with the pandoraviruses. They share 60 unique genes and the roughly spherical (0.6µm) mollivirions present an external tegument resembling the pandoravirions. Both viruses have an early nuclear phase – the pithovirus, despite its amphora-shaped virions, has a fully cytoplasmic cycle. Our work raised questions on the origin of these intriguing viral families and their position in the tree of life. My project is unique as it will address the coevolution of these viruses and their amoebal hosts by focusing on specific features of the virions in two overall aims. 1) Promising preliminary results led us to hypothesize that a progressive transition from the rigid icosahedral virions to the more plastic amphora-shaped particles was made possible through hijacking of the host cellulose synthesis pathway by the ancestor of pandoraviruses. 2) The icosahedral mimivirus package its genome in a complex rod-shaped structure. My team will investigate this structure to unveil possible evolutionary links with the genome packaging systems in the cellular world. We will characterize the machinery responsible for such organization. These two high-risk/high-gain aims will continue to revisit the concept of virus and their evolutionary trajectory in the living world.
Ámbito científico
Palabras clave
Programa(s)
Régimen de financiación
ERC-ADG - Advanced GrantInstitución de acogida
75794 Paris
Francia