Previously unknown marine ssDNA satellite viruses associating to diatom ssDNA viruses

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K14963
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Aquatic bioproduction science
• Research Institution: Fisheries Research and Education Agency
• Principal Investigator: Tomaru Yuji 国立研究開発法人水産研究・教育機構, 瀬戸内海区水産研究所, 主任研究員 (10416042)
• Research Collaborator: Kimura Kei
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 珪藻 / ssDNAウイルス / サテライト / 沿岸

Outline of Final Research Achievements

This study demonstrated the basic biological characters of a virus-like agent that infects the marine planktonic diatom Chaetoceros debilis. The virus-like agent was considered to be composed of a known diatom ssDNA virus (>30 nm in diameter) and a previously unknown smaller virus-like particle (VLP) (~20 nm). Based on the morphologic and genomic analysis, the smaller VLP was considered to be a satellite virus associating to the diatom ssDNA virus. Phylogentic analysis for a putative capsid protein gene of the smaller VLP revealed that it makes monophyly with those of unrevealed environmental viruses, which is independent of the diatom ssDNA viruses. Furthermore, the satellite like agents that infectious to a different diatom species were detected from sediment pore waters in western Japan. These results might suggest the satellite viruses associating to the diatom ssDNA viruses are present in Japanese coastal waters as active agents, although their ecological roles are still unknown.

Free Research Field

海洋微生物生態学

Academic Significance and Societal Importance of the Research Achievements

環境メタゲノム研究は技術の発展とともに急速にデータが蓄積しているものの、次世代シーケンスに基づくウイルス様配列の正体は、現在全く理解されていない。本研究はそのような未知ウイルスに対して意味付けを行い、それらの海洋における重要性を評価するという観点できわめて重要な作業である。現在、海洋の珪藻研究は分子生物学と融合したフロンティア分野であり、海外からの注目も高い。新奇性が高く、生物地球科学的にも重要な成果が次々に生まれている分子珪藻学分野においても、今回発見した新種珪藻ウイルスの性状解明は大きな意味を持つ。