title: Virophage control of antarctic algal host-virus dynamics.
abstract: Viruses are abundant ubiquitous members of microbial communities and in the marine environment affect population structure and nutrient cycling by infecting and lysing primary producers. Antarctic lakes are microbially dominated ecosystems supporting truncated food webs in which viruses exert a major influence on the microbial loop. Here we report the discovery of a virophage (relative of the recently described Sputnik virophage) that preys on phycodnaviruses that infect prasinophytes (phototrophic algae). By performing metaproteogenomic analysis on samples from Organic Lake, a hypersaline meromictic lake in Antarctica, complete virophage and near-complete phycodnavirus genomes were obtained. By introducing the virophage as an additional predator of a predator-prey dynamic model we determined that the virophage stimulates secondary production through the microbial loop by reducing overall mortality of the host and increasing the frequency of blooms during polar summer light periods. Virophages remained abundant in the lake 2 y later and were represented by populations with a high level of major capsid protein sequence variation (25-100% identity). Virophage signatures were also found in neighboring Ace Lake (in abundance) and in two tropical lakes (hypersaline and fresh), an estuary, and an ocean upwelling site. These findings indicate that virophages regulate host-virus interactions, influence overall carbon flux in Organic Lake, and play previously unrecognized roles in diverse aquatic ecosystems.
authors: School of Biotechnology and Biomolecular Sciences, Centre for Marine Bio-Innovation, and Bioanalytical Mass Spectrometry Facility, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Sheree
authors: S
authors: Yau
authors: Federico M
authors: FM
authors: Lauro
authors: Matthew Z
authors: MZ
authors: DeMaere
authors: Mark V
authors: MV
authors: Brown
authors: Torsten
authors: T
authors: Thomas
authors: Mark J
authors: MJ
authors: Raftery
authors: Cynthia
authors: C
authors: Andrews-Pfannkoch
authors: Matthew
authors: M
authors: Lewis
authors: Jeffrey M
authors: JM
authors: Hoffman
authors: John A
authors: JA
authors: Gibson
authors: Ricardo
authors: R
authors: Cavicchioli
mesh_terms: D000864:Antarctic Regions; D001483:Base Sequence; D005618:Fresh Water / Q000821:virology*; D014644:Genetic Variation; D016679:Genome, Viral / Q000235:genetics*; D054892:Metagenome / Q000235:genetics*; D008969:Molecular Sequence Data; D017862:Phycodnaviridae / Q000145:classification / Q000235:genetics* / Q000502:physiology*; D010802:Phylogeny; D058009:Stramenopiles