Subversion of host cell signaling: The arsenal of Rickettsial species

Abstract

Rickettsia is a genus of nonmotile, Gram-negative, non-spore-forming, highly pleomorphic bacteria that cause severe epidemic rickettsioses. The spotted fever group and typhi group are major members of the genus Rickettsia. Rickettsial species from the two groups subvert diverse host cellular processes, including membrane dynamics, actin cytoskeleton dynamics, phosphoinositide metabolism, intracellular trafficking, and immune defense, to promote their host colonization and intercellular transmission through secreted effectors (virulence factors). However, lineage-specific rickettsiae have exploited divergent strategies to accomplish such challenging tasks and these elaborated strategies focus on distinct host cell processes. In the present review, we summarized current understandings of how different rickettsial species employ their effectors’ arsenal to affect host cellular processes in order to promote their own replication or to avoid destruction.

Anaphylatoxin signaling activates macrophages to control intracellular Rickettsia proliferation

“…The relative importance of each of these host activation markers has yet to be determined, but together, these proteins serve as the foundation for examining how Rickettsia “deactivates” infected host cells. Rickettsial manipulation of host signaling is currently exemplified at a molecular level by modulation of PI3K and Arf6 activity but is also apparent by noninflammatory changes to transcriptional and proteomic profiles induced by infection ( 15 , 60 , 108 – 110 ). It is clear that there is an ongoing battle for cell signaling mechanisms occurring within the cytoplasm of Rickettsia -infected leukocytes.…”

The intricate dance: host autophagy and Coxiella burnetii infection

“…The effector proteins of C. burnetii , similar to those of Legionella species ( Song et al, 2021 , 2022 ; Fu J. et al, 2022 ), play a crucial role as key virulence factors by being transported into the host cell cytoplasm. Once inside, they strategically manipulate host cell functions to promote bacterial survival and replication ( Huang et al, 2022 ; Zhang et al, 2022 ).…”

Editorial: Innate immunity against intracellular bacteria: mechanisms and strategies

“…However, the battle between intracellular bacteria and the immune system is not a one-sided affair. Intracellular bacteria have evolved various mechanisms to evade or subvert the host immune response (5)(6)(7). One such mechanism is the ability to modulate host cell signaling pathways to evade detection by PRRs or to interfere with immune cell activation (8).…”