Descrizione del progetto
Traiettoria evolutiva dei virus giganti nel mondo cellulare
Mimivirus (famiglia Mimiviridae) è un virus icosaedrico gigante visibile al microscopio ottico, che usa l’ameba come ospite naturale. La scoperta di questo e di altri virus giganti ha sollevato domande sulla loro origine ed evoluzione. Il progetto VIREVOL, finanziato dall’UE, studierà la coevoluzione di questi virus e dei loro ospiti amebici, concentrandosi sulle caratteristiche specifiche dei virioni. L’ipotesi dello studio è che una transizione dai virioni rigidi icosaedrici alle particelle più plastiche a forma di anfora sia avvenuta tramite il dirottamento del percorso di sintesi della cellulosa dell’ospite da parte dell’antenato di questi virus. La ricerca si concentrerà anche sulla struttura a bastoncello e sull’organizzazione del loro genoma per scoprire i legami evolutivi con i sistemi di impacchettamento del genoma nel mondo cellulare.
Obiettivo
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.
Campo scientifico
Parole chiave
Programma(i)
Argomento(i)
Meccanismo di finanziamento
ERC-ADG - Advanced GrantIstituzione ospitante
75794 Paris
Francia