Elucidation of bacterial virulence systems using in vivo experimental evolutionary systems

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K22523
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 49:Pathology, infection/immunology, and related fields
• Research Institution: Okayama University
• Principal Investigator: KAITO Chikara 岡山大学, 医歯薬学域, 教授 (60420238)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: 実験的進化 / LPSトランスポーター / ペリプラズムグルカン

Outline of Final Research Achievements

On Earth, since the emergence of multicellular organisms, environmental bacteria are thought to have evolved into commensal and pathogenic bacteria by adapting and evolving the functions of various genes to the internal environment of multicellular organisms, but the molecular mechanisms leading to the differences between pathogenic and nonpathogenic bacteria remain largely unexplored. In this study, using a silkworm infection model, we experimentally captured the process by which nonpathogenic bacteria accumulate mutations in their own genes and develop a state in which they are not eliminated by the host immune system or outperform the host immune system. By analyzing E. coli mutant isolates, we found amino acid substitution mutations in the LPS transporter and gene disruptions in periplasmic synthase that cause increased virulence.

Free Research Field

分子生物学，生化学，微生物学

Academic Significance and Societal Importance of the Research Achievements

本研究は，カイコ感染モデルを利用して非病原性細菌から病原性細菌への進化プロセスを捉えることに成功した。さらに，病原性上昇を引き起こす細菌の遺伝子変異を２種類同定した。これらの研究成果は，病原性細菌の進化プロセスを研究する新たな方法論を確立した点，ならびに，細菌の感染能力獲得の新たな分子メカニズムを明らかにした点で学術的意義がある。また，高病原性化を引き起こす遺伝子変異の検出は高病原性の細菌変異株を検出する新たな技術につながり，社会的意義がある。