title: Snapshot of virus evolution in hypersaline environments from the characterization of a membrane-containing Salisaeta icosahedral phage 1.
abstract: The multitude of archaea and bacteria inhabiting extreme environments has only become evident during the last decades. As viruses apply a significant evolutionary force to their hosts, there is an inherent value in learning about viruses infecting these extremophiles. In this study, we have focused on one such unique virus-host pair isolated from a hypersaline environment: an icosahedral, membrane-containing double-stranded DNA virus--Salisaeta icosahedral phage 1 (SSIP-1) and its halophilic host bacterium Salisaeta sp. SP9-1 closely related to Salisaeta longa. The architectural principles, virion composition, and the proposed functions associated with some of the ORFs of the virus are surprisingly similar to those found in viruses belonging to the PRD1-adenovirus lineage. The virion structure, determined by electron cryomicroscopy, reveals that the bulk of the outer protein capsid is composed of upright standing pseudohexameric capsomers organized on a T = 49 icosahedral lattice. Our results give a comprehensive description of a halophilic virus-host system and shed light on the relatedness of viruses based on their virion architecture.
authors.affiliation: Institute of Biotechnology and Department of Biosciences, Biocenter 2, University of Helsinki, FI-00014 Helsinki, Finland.
authors.forename: Antti P
authors.initials: AP
authors.lastname: Aalto
authors.forename: David
authors.initials: D
authors.lastname: Bitto
authors.forename: Janne J
authors.initials: JJ
authors.lastname: Ravantti
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Bamford
authors.forename: Juha T
authors.initials: JT
authors.lastname: Huiskonen
authors.forename: Hanna M
authors.initials: HM
authors.lastname: Oksanen
mesh_terms: D001435:Bacteriophages / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology / Q000648:ultrastructure; D041963:Bacteroidetes / Q000821:virology*; D001483:Base Sequence; D002213:Capsid / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D004279:DNA, Viral / Q000235:genetics; D004777:Environment; D019143:Evolution, Molecular; D016679:Genome, Viral; D054884:Host-Pathogen Interactions; D021621:Imaging, Three-Dimensional; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012462:Saline Solution, Hypertonic; D016662:Virus Integration
chemical_list: D004279:DNA, Viral; D012462:Saline Solution, Hypertonic