Virophage control of antarctic algal host-virus dynamics

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Yau, S, Lauro, FM, DeMaere, MZ, Brown, MV, Thomas, T, Raftery, MJ, Andrews-Pfannkoch, C, Lewis, M, Hoffman, JM, Gibson, JA, Cavicchioli, R
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Academy of Science 2011
• Subjects: Biological Sciences; Microbiology; Microbial Ecology; Ace Lake; Antarctic; Sputnik; Antarc*; Antarctica
• Online Access: https://doi.org/10.1073/pnas.1018221108; http://www.ncbi.nlm.nih.gov/pubmed/21444812; http://ecite.utas.edu.au/77816

Viruses are abundant ubiquitous members of microbial communitiesand in the marine environment affect population structureand nutrient cycling by infecting and lysing primary producers.Antarctic lakes are microbially dominated ecosystems supportingtruncated food webs in which viruses exert a major influence onthe microbial loop. Here we report the discovery of a virophage(relative of the recently described Sputnik virophage) that preyson phycodnaviruses that infect prasinophytes (phototrophic algae).By performing metaproteogenomic analysis on samples fromOrganic Lake, a hypersaline meromictic lake in Antarctica, completevirophage and near-complete phycodnavirus genomes wereobtained. By introducing the virophage as an additional predatorof a predatorprey dynamic model we determined that the virophagestimulates secondary production through the microbialloop by reducing overall mortality of the host and increasing thefrequency of blooms during polar summer light periods. Virophagesremained abundant in the lake 2 y later and were representedby populations with a high level of major capsid proteinsequence variation (25100% identity). Virophage signatures werealso found in neighboring Ace Lake (in abundance) and in twotropical lakes (hypersaline and fresh), an estuary, and an oceanupwelling site. These findings indicate that virophages regulatehostvirus interactions, influence overall carbon flux in OrganicLake, and play previously unrecognized roles in diverse aquaticecosystems.