Evaluating removal of unculturable human enteric viruses during drinking water treatment by using DNA-encapsulated virus-like particles

Research Project

Project/Area Number	17K20054
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Research Field	Environmental conservation measure and related fields
Research Institution	Hokkaido University
Principal Investigator	Matsushita Taku 北海道大学, 工学研究院, 准教授 (30283401)
Co-Investigator(Kenkyū-buntansha)	白崎伸隆北海道大学, 工学研究院, 准教授 (60604692)
Research Collaborator	Shirakawa Daiki
Project Period (FY)	2017-06-30 – 2019-03-31
Project Status	Completed (Fiscal Year 2018)
Budget Amount *help	¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000) Fiscal Year 2018: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000) Fiscal Year 2017: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Keywords	環境保全学 / 土木環境システム / ウイルス / 環境技術
Outline of Final Research Achievements	To evaluate the removals of unculturable viruses during drinking water treatment, we attempted to lower the quantification limit of virus-like particles (VLPs) of the viruses by encapsulating foreign DNA to the VLPs, which enables us to evaluate the removals of unculturable viruses by measuring the encapsulated DNA with PCR. We firstly confirmed the followings by using a phage (model virus): (1) a reductant addition unfolded the phage capsid to a constituent protein, (2) an Au nanoparticle (model DNA) addition to the unfolded protein followed by a ClCl2 addition refolded the protein to the same structure as the native phage, and (3) the Au nanoparticles were encapsulated in the refolded proteins. We secondly attempted to encapsulate foreign DNAs to the norovirus VLPs, but the encapsulating ratio was lower ( 0.001%) than expected. Mass balance revealed that the low ratio was due to the low affinity between the VLPs and the DNA used.
Academic Significance and Societal Importance of the Research Achievements	本研究で行う、DNA封入VLPsにより浄水処理性を評価しようとする試みは世界的にも全く前例がなく、いかなる「培養不可能なウイルス」に対しても適用可能であるため、これまで浄水処理性を調べることができなかったサポウイルスやE型肝炎ウイルスなどの他のウイルスの浄水処理性の評価が可能となる。また、得られる結果は、実際の処理場の技術者にも大きなインパクトを与えるとともに、ウイルスの水道水質基準への組み込みについての議論にも大きく貢献でき、社会的に大きい意義を持つのみならず、これまでの病原性微生物の浄水処理性評価法を大きく変革・転換させる可能性を持った極めて意欲的な研究となり、学術的な意義も極めて大きい。