A Tale of Many Tails: Bacterial Actin-Based Motility and the Host Interplay

Intracellular microbes that deploy actin-based motility (ABM) as a virulence mechanism are phylogenetically diverse pathogens that cause a wide range of infections in animals and humans. These include bacteria that share pathogenic features such as the invasion of host cells, the rupture of intracellular compartments, and exploitation of host cytoskeletal proteins for cytosolic movement. The virulence factors that mediate ABM and the underlying molecular mechanisms differ substantially across genera and even within species when multiple proteins are encoded within a genome. Emerging evidence from these pathogens now reveals significant heterogeneity in bacterial actin-tail architecture, motility behaviors across distinct host-cell contexts, and susceptibility to immune restriction. This review provides an update on the recent advances in bacterial ABM, highlighting the emerging complexities of the interplay between host immunity and this important microbial virulence mechanism.