Molecular epidemiology of novel bovine-associated pVAPN in Rhodococcus equi and genetic analysis of the plasmid

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H02351
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 42020:Veterinary medical science-related
• Research Institution: Kitasato University
• Principal Investigator: Takai Shinji 北里大学, 獣医学部, 教授 (80137900)
• Co-Investigator(Kenkyū-buntansha): 角田 勤 北里大学, 獣医学部, 准教授 (80317057)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: ロドコッカス・エクイ / 病原性プラスミド / 毒力関連抗原 / 病原性遺伝子 / 反芻獣 / 山羊 / 牛 / 分子疫学調査

Outline of Final Research Achievements

Rhodococcus equi isolates from the infected Boa goat in Okinawa reported in 2015 were reexamined by the PCR for VapN gene. The VapN gene was detected in all the 32 isolates from the lesions of the goat, and they possessed a 120-kb linear virulence plasmid. Ten (34.5%) of 29 environmental isolates from soil in the goat farm were VapN-positive. Serological surveillance in goats at the farm was done using an enzyme-linked immunosorbent assay with recombinant glutathione S-transferase-tagged VapN as an immobilized antigen, and revealed that the VapN antibody titer was elevated in 12 of 42 goats. Subsequently, we attempted to isolate R. equi from the feces of goats and soil on Farm A. vapN-positive R. equi was isolated from the feces of Goat No. 27 and one soil sample near the shed. The pulsed-field gel electrophoresis (PFGE) patterns of five vapN-harboring R. equi strains show two PFGE patterns. Further study on the epidemiology of VapN-positive R. equi in ruminants in Japan is needed.

Free Research Field

獣医学

Academic Significance and Societal Importance of the Research Achievements

ロドコッカス・エクイはウマの化膿性肺炎の起因菌であるが、近年、牛・山羊など反芻動物に対して新規毒力関連抗原VapNをコードする線状プラスミドを保有し、肉芽腫性疾患を引き起こすことが明らかとなった。本研究は、我が国における山羊や牛における本菌の疫学調査が殆ど調査されていない。本研究では簡便にスクリーニングできるELISA法を確立し、疫学調査が容易となったことは学術的意義が高い。