Project description:We describe a fourth type of giant virus infecting Acanthamoeba, Mollivirus sibericum, isolated from the same permafrost sample than Pithovirus sibericum.
Project description:We describe a fourth type of giant virus infecting Acanthamoeba, Mollivirus sibericum, isolated from the same permafrost sample than Pithovirus sibericum.
Project description:With its 2.5 Mb DNA genome packed in amphora-shaped particles of bacterium-like dimension (1.2 µm in length, 0.5 µm in diameter), the Acanthamoeba-infecting Pandoravirus salinus remained the most spectacular and intriguing virus since its description in 2013. Following its isolation from shallow marine sediment off the coast of central Chile, that of its relative Pandoravirus dulcis from a fresh water pond near Melbourne, Australia, suggested that they were the first representatives of an emerging worldwide-distributed family of giant viruses. This was further suggested when P. inopinatum discovered in Germany, was sequenced in 2015. We now report the isolation and genome sequencing of three new strains (P. quercus, P.neocaledonia, P. macleodensis) from France, New Caledonia, and Australia. Using a combination of transcriptomic, proteomic, and bioinformatic analyses, we found that these six viruses share enough distinctive features to justify their classification in a new family, the Pandoraviridae, distinct from that of other large DNA viruses.
Project description:Giant viruses are extraordinary members of the virosphere due to their structural complexity and high diversity in gene content. Haptophytes are ecologically important primary producers in the ocean, and all known viruses that infect haptophytes are giant viruses. Our in-depth electron microscopic, phylogenomic and virion proteomic analyses of two haptophyte-infecting giant viruses, Haptolina ericina virus RF02 (HeV RF02) and Prymnesium kappa virus RF02 (PkV RF02), unravel their large capacity for host manipulation and arsenals that functions during the infection cycle from virus entry to release. The virus infection induces significant morphological changes of host cell that are manipulated to build a virus proliferation factory. Both viruses’ genomes encode a putative nucleoprotein (dinoflagellate/viral nucleoprotein; DVNP), which was also found in the virion proteome of PkV RF02. Phylogenetic analysis suggests that DVNPs are widespread in marine giant metaviromes. Furthermore, the analysis shows that the dinoflagellate homologues were possibly acquired from viruses of the order Imitervirales.
Project description:Acanthamoeba-infecting Mimiviridae belong to three clades: Mimiviruses (A), Moumouviruses (B) and Megaviruses (C). The uniquely complex mobilome of these giant viruses includes virophages and linear 7 kb-DNA molecules called “transpovirons”. We recently isolated a new virophage (Zamilon vitis) and two new transpovirons (maBtv and mvCtv) respectively associated to B-clade and C-clade Mimiviridae. We used the capacity of the Zamilon virophage to replicate both on B-clade and C-clade host viruses to investigate the three partite interaction network governing the propagation of transpovirons. We notably performed proteomic comparisons of host viruses and virophage particles carrying or cleared of transpovirons in search of proteins involved in this adaptation process. These experiments revealed that transpoviron-encoded proteins are synthetized during the combined Mimiviridae/virophage/transpoviron replication process and are specifically incorporated into the virophage and Mimiviridae virions together with the cognate transpoviron DNA. This is a unique example of intricate commensalism in the viral world, where the Zamilon virophage and the transpoviron depend on their host giant virus to replicate, and the transpoviron depends on the virophage to propagate from one host virus to another.
Project description:This project describes the protein composition of the Cafeteria roenbergensis virus (CroV, strain BV-PW1: TaxID 693272) particle, a giant marine DNA virus that infects the heterotrophic nanoflagellate microeukaryote C. roenbergensis. CroV is a member of the Nucleo-Cytoplasmic Large DNA Virus clade and related to Acanthamoeba polyphaga mimivirus. CroV possesses a DNA genome of ~730 kilobase pairs that encodes 544 predicted proteins. We analyzed the protein composition of purified CroV particles by liquid chromatography - tandem mass spectrometry (LC-MS/MS) and identified 141 virion-associated CroV proteins. Predicted functions could be assigned to 37% of these proteins, which include structural proteins as well as enzymes for transcription, DNA repair, redox reactions and protein modification. Homologs of 36 CroV virion proteins have previously been found in the virion of Acanthamoeba polyphaga mimivirus. This study shows that giant DNA virus particles contain more than one hundred viral proteins that include specific enzymatic functions.
2014-05-22 | PXD000993 | Pride
Project description:Isolation and characterization of 14 Enterococcus faecalis infecting bacteriophages