Symbiont-Mediated Defense against Legionella pneumophila in Amoebae (MBio, 2019, 14:10(3))

報告日期: 2019/10/22
報告時間: 17:10/18:00
報告學生: 王昱仁
講評老師: 彭貴春

Symbiont-Mediated Defense against Legionella pneumophila in Amoebae

König Let al, MBio, 14;10(3), 2019

SpeakerYu-Jen Wang(王昱仁)                                       Time17:00~17:50 Oct. 22. 2019

CommentatorGuey-Chuen Perng, Ph.D.(彭貴春老師)     PlaceRoom 602


Legionella pneumophila is a crucial opportunistic microorganism from theenvironment to humans. In the environment,free-living amoebae as an important host who provides nutrients and shelterfor highly efficient intracellular proliferation of L. pneumophila, which finallyleads to lysis of the protest [1]. However, the characterize of other microbesfor the mechanism of interaction between L. pneumophila and host is poorly understood [2]. In this research, the author used auniversal amoeba and bacterial endosymbiont to investigate the impact of thiscommon association on L. pneumophila infection. The author demonstrates that L. pneumophilaproliferation was strictly suppressed in Acanthamoeba castellanii containingthe Protochlamydia amoebophila. The amoebae survived the infectionand were able to keep growth. Diverse environmental amoeba isolatesharboring the symbiont were equally well protected as different L. pneumophila isolateswere diminished, suggesting the mechanism of P. amoebophila mediateddefense. Next, protection was not mediated by impaired L. pneumophila uptake.On the other hand, the author observed the virulence reduction of L. pneumophila which was released fromsymbiont-containing amoebae. Precise gene expression changes in the presenceof the symbiont show that interference with the transition to the transmissivephase impedes the L. pneumophila infection. Finally, the data show that the defensiveresponse of amoebae containing P. amoebophila lets the amoebae withimmunological-like memory. Given that mutualistic associationsbetween bacteria and amoebae, P. amoebophila andpotentially other amoeba endosymbionts was a critical point in environmentalsurvival, abundance, and virulence of L. pneumophila, thereby influence theopportunity of human infection.


  1. Fritsche T et al.1993.Occurrence of bacterial endosymbionts in Acanthamoeba spp. isolated from corneal and environmental specimens and contact lenses. J Clin Microbiol 31:1122–1126. (1993)
  2. Horn M. 2008. Chlamydiae as symbionts in eukaryotes. Annu Rev Microbiolc