AUTHOR=Watanabe Kenta , Higuchi Yusei , Shimmura Mizuki , Tachibana Masato , Fujishima Masahiro , Shimizu Takashi , Watarai Masahisa 

TITLE=Peculiar Paramecium Hosts Fail to Establish a Stable Intracellular Relationship With Legionella pneumophila

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.596731

DOI=10.3389/fmicb.2020.596731

ISSN=1664-302X

ABSTRACT=<p><italic>Legionella pneumophila</italic>, an intracellular human pathogen, establishes intracellular relationships with several protist hosts, including <italic>Paramecium caudatum</italic>. <italic>L. pneumophila</italic> can escape the normal digestion process and establish intracellular relationships in <italic>Paramecium</italic>. In this study, we identify new <italic>Paramecium</italic> strains that significantly reduce the number of <italic>L. pneumophila</italic> during infection. As a result, stable intracellular relationships between <italic>L. pneumophila</italic> and these <italic>Paramecium</italic> strains were not observed. These digestion-type <italic>Paramecium</italic> also showed high efficiency for <italic>Escherichia coli</italic> elimination compared to other strains of <italic>Paramecium</italic>. These results suggest that the digestion-type strains identified have high non-specific digestion activity. Although we evaluated the maturation process of <italic>Legionella</italic>-containing vacuoles (LCVs) in the <italic>Paramecium</italic> strains using LysoTracker, there were no discriminative changes in these LCVs compared to other <italic>Paramecium</italic> strains. Detailed understanding of the mechanisms of high digestion efficiency in these strains could be applied to water purification technologies and <italic>L. pneumophila</italic> elimination from environmental water.</p>