title: Evolutionary history of ssDNA bacilladnaviruses features horizontal acquisition of the capsid gene from ssRNA nodaviruses.
abstract: Bacilladnaviruses have single-stranded (ss) DNA genomes and infect diatoms, a major group of unicellular algae widespread in aquatic habitats. Despite their ecological importance, the provenance and relationships of bacilladnaviruses to other eukaryotic viruses remain unclear. Accordingly, they are currently classified into the 'floating' genus Bacilladnavirus. Here we present three new bacilladnavirus genomes recovered from a mollusc Amphibola crenata and benthic sediments from the Avon-Heathcote estuary in New Zealand. Our analysis shows that the rolling-circle replication-initiation proteins of bacilladnaviruses display unique conserved motifs and in phylogenetic trees form a monophyletic clade separated from other groups of ssDNA viruses. Unexpectedly, distant homology detection combined with structural modeling indicates that bacilladnavirus capsid proteins are homologous to those of ssRNA viruses from the Nodaviridae family. Considering the sequence diversity within the expanding Bacilladnavirus genus, we argue that classification of these viruses has to be revised and the current genus upgraded to the family level.
authors.affiliation: Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, Vilnius 10257, Lithuania. Electronic address: d.kazlauskas@ibt.lt.
authors.forename: Darius
authors.initials: D
authors.lastname: Kazlauskas
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand; Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA. Electronic address: anisha.dayaram@gmail.com.
authors.forename: Anisha
authors.initials: A
authors.lastname: Dayaram
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand; Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin 10315, Germany. Electronic address: simona.kraberger@gmail.com.
authors.forename: Simona
authors.initials: S
authors.lastname: Kraberger
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand. Electronic address: sharyn.goldstien@canterbury.ac.nz.
authors.forename: Sharyn
authors.initials: S
authors.lastname: Goldstien
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand; The Biodesign Center for Fundamental and Applied Microbiomics, School of Life sciences, Center for Evolution and Medicine, Arizona State University, Tempe, AZ 85287, USA; Structural Biology Research Unit, Department of Clinical Laboratory Sciences, University of Cape Town, Observatory 7700, South Africa. Electronic address: arvind.varsani@asu.edu.
authors.forename: Arvind
authors.initials: A
authors.lastname: Varsani
authors.affiliation: Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, 25 rue du Docteur Roux, Paris 75015, France. Electronic address: krupovic@pasteur.fr.
authors.forename: Mart
authors.initials: M
authors.lastname: Krupovic
mesh_terms: D000818:Animals; D036022:Capsid Proteins / Q000235:genetics*; D004267:DNA Viruses / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification / Q000648:ultrastructure; D004270:DNA, Circular / Q000235:genetics; D004277:DNA, Single-Stranded / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D019143:Evolution, Molecular; D049851:Gastropoda / Q000821:virology*; D014644:Genetic Variation / Q000235:genetics; D016679:Genome, Viral / Q000235:genetics; D009520:New Zealand; D030381:Nodaviridae / Q000235:genetics; D014779:Virus Replication / Q000235:genetics
chemical_list: D036022:Capsid Proteins; D004270:DNA, Circular; D004277:DNA, Single-Stranded; D004279:DNA, Viral
keywords: Bacilladnavirus; CRESS DNA viruses; Capsid protein; Nodaviridae; ssDNA viruses