ニシダ　タカシ   NISHIDA Takashi   西田　隆司    所属   医学部 医学科    職種   助教
論文種別	原著
言語種別	英語
査読の有無	査読あり
表題	Survival of Bordetella bronchiseptica in Acanthamoeba castellanii.
掲載誌名	正式名：Microbiology spectrum 略　 称：Microbiol Spectr ISSNコード：21650497/21650497
掲載区分	国外
巻・号・頁	11(2),pp.e0048723
著者・共著者	Dendi Krisna Nugraha, Takashi Nishida, Yuki Tamaki, Yukihiro Hiramatsu, Hiroyuki Yamaguchi, Yasuhiko Horiguchi
発行年月	2023/03
概要	The respiratory pathogenic bacterium Bordetella bronchiseptica can persistently survive in terrestrial and aquatic environments, providing a source of infection. However, the environmental lifestyle of the bacterium is poorly understood. In this study, expecting repeated encounters of the bacteria with environmental protists, we explored the interaction between B. bronchiseptica and a representative environmental amoeba, Acanthamoeba castellanii, and found that the bacteria resisted amoeba digestion and entered contractile vacuoles (CVs), which are intracellular compartments involved in osmoregulation, to escape amoeba cells. In prolonged coculture, A. castellanii supported the proliferation of B. bronchiseptica. The avirulent Bvg- phase, but not the virulent Bvg+ phase, of the bacteria was advantageous for survival in the amoebae. We further demonstrate that two Bvg+ phase-specific virulence factors, filamentous hemagglutinin and fimbriae, were targeted for predation by A. castellanii. These results are evidence that the BvgAS two-component system, the master regulator for Bvg phase conversion, plays an indispensable role in the survival of B. bronchiseptica in amoebae. IMPORTANCE The pathogenic bacterium Bordetella bronchiseptica, which causes respiratory diseases in various mammals, exhibits distinct Bvg+ and Bvg- phenotypes. The former represents the virulent phase, in which the bacteria express a set of virulence factors, while the role of the latter in the bacterial life cycle remains to be understood. In this study, we demonstrate that B. bronchiseptica in the Bvg- phase, but not the Bvg+ phase, survives and proliferates in coculture with Acanthamoeba castellanii, an environmental amoeba. Two Bvg+ phase-specific virulence factors, filamentous hemagglutinin and fimbriae, were targeted by A. castellanii predation. B. bronchiseptica turns into the Bvg- phase at temperatures in which the bacteria normally encounter these amoebae. These findings demonstrate that the Bvg- phase of B. bronchiseptica is advantageous for survival outside mammalian hosts and that the bacteria can utilize protists as transient hosts in natural environments.
DOI	10.1128/spectrum.00487-23
PMID	36971600