2018 Fiscal Year Final Research Report

Does influenza C virus bud from lipid raft?

Research Project

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Project/Area Number	16K08816
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Virology
Research Institution	Iwate Medical University
Principal Investigator	Muraki Yasushi 岩手医科大学, 医学部, 教授 (00241688)
Co-Investigator(Kenkyū-buntansha)	野田岳志京都大学, ウイルス・再生医科学研究所, 教授 (00422410) 本郷誠治山形大学, 医学部, 教授 (90229245) 佐々木裕岩手医科大学, 医学部, 助教 (80526062)
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	C型インフルエンザウイルス / 出芽 / budozone / 粒子形成 / 細胞膜 / 脂質ラフト
Outline of Final Research Achievements	Accumulating evidence shows that influenza A virus buds from lipid raft of the infected cells. In contrast, we found that hemagglutinin-esterase-fusion (HEF) of influenza C virus could not be recovered in the lipid raft fraction of infected cells, suggesting that the budozone of influenza C virus is a region except lipid raft. The aim of the present project is to elucidate the budozone of influenza C virus. The lipid content of influenza C viruses grown in chicken eggs was not different from that of influenza A viruses, suggesting avian species may not be suitable for the analysis. Virus-infected cells were treated with methyl-beta-cyclodextrin (M-beta-CD), an inhibitor for raft biogenesis. The cells died due to the toxic effect of M-beta-CD. Influenza C virus-like particles (VLPs) were generated. The HEF, CM2 and NP proteins in VLPs and VLP-producing cells were recovered in detergent-insoluble fraction, suggesting that the budozone of influenza C virus is a region except lipid raft.
Free Research Field	ウイルス学
Academic Significance and Societal Importance of the Research Achievements	C型インフルエンザウイルスの病原性が低い理由として、感染性粒子の形成効率が低いことが推測される。この形成効率の低さは、C型インフルエンザウイルスの出芽部位budozoneが形質膜上の脂質ラフトlipid raft以外の領域であり、ウイルスを構成する成分（タンパクとゲノム）の集積の効率が悪いためであると考えられる。今回、この作業仮説を示唆する知見が得られた。従来のインフルエンザウイルスとは異なったものであり、インフルエンザウイルス学の粒子形成の分野に新規の概念を提唱することとなる。