Characterization of T7SS in S. intermedius isolated from brain abscess to blood-brain barrier disruption

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K16257
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 49050:Bacteriology-related
• Research Institution: National Institute of Infectious Diseases
• Principal Investigator: Hashino Masanori 国立感染症研究所, 病原体ゲノム解析研究センター, 主任研究官 (30783633)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: Streptococcus / 7型分泌装置 / 膿瘍形成 / 細菌感染性脳膿瘍

Outline of Final Research Achievements

Streptococcus intermedius (SI) is known as one of the bacteria causing brain and liver abscess. However, specific virulence factors involved in abscess formation have not been identified. SI TYG1620 strain was isolated as the causative agent from a brain abscess in an infant. In this study, we identified the cytotoxic factor secreted via Type 7 Secretion System (T7SS) in TYG1620 strain. In addition, this cytotoxic factor is also involved in the secretion of other T7SS-dependent secretory proteins. These results suggested TYG1620 strain produces a T7SS-dependent cytotoxic factor, not any known virulence factors.

Free Research Field

病原細菌学

Academic Significance and Societal Importance of the Research Achievements

重篤な症状を引起す細菌感染性脳膿瘍は、予防・制御方法の確立が医学上重要な課題となっている。しかしながら、脳膿瘍原因菌であるStreptococcus intermedius (SI)の病態誘導機序は未解明である。本研究では、脳膿瘍由来のSI TYG1620株において、既知の病原因子とは異なり、Type 7 Secretion System依存的に分泌され細胞傷害性に寄与することが示唆された因子を見出した。本研究の成果は、SIにおける新たな病原因子を提示するものであるとともに、TYG1620株の臨床的背景から血液脳関門突破能を含めた脳膿瘍形成機序の解明に重要な知見となることが期待される。