Abstract
Outer membrane vesicles are nano-sized microvesicles shed from the outer membrane of Gram-negative bacteria and play important roles in immune priming and disease pathogenesis. However, our current mechanistic understanding of vesicle-host cell interactions is limited by a lack of methods to study the rapid kinetics of vesicle entry and cargo delivery to host cells. Here, we describe a highly sensitive method to study the kinetics of vesicle entry into host cells in real-time using a genetically encoded, vesicle-targeted probe. We found that the route of vesicular uptake, and thus entry kinetics and efficiency, are shaped by bacterial cell wall composition. The presence of lipopolysaccharide O antigen enables vesicles to bypass clathrin-mediated endocytosis, which enhances both their entry rate and efficiency into host cells. Collectively, our findings highlight the composition of the bacterial cell wall as a major determinant of secretion-independent delivery of virulence factors during Gram-negative infections.
Highlights
Outer membrane vesicles (OMVs) are nano-sized proteoliposomes released from the bacterial cell envelope [1]
We developed a method to monitor the rapid vesicle entry into host cells in real-time. This method highlighted differences in kinetics and entry route of vesicles into host cells, which varied with the bacterial cell wall composition and the vesicle surface
Using this assay to study entry of OMVs from different E. coli serotypes and pathovars into host cells, we identified key bacterial and host factors that determine the route of entry, and thereby kinetics and efficiency of vesicular cargo delivery and trafficking
Summary
Outer membrane vesicles (OMVs) are nano-sized proteoliposomes released from the bacterial cell envelope [1]. OMVs contain and deliver a broad range of cargos, from large hydrophobic molecules to DNA, making them a versatile and generalised form of secretion that enhances bacterial fitness in hostile environments [3,4,5,6]. They contribute significantly to pathogenesis, via the delivery of virulence factors such as toxins, adhesins and immunomodulatory compounds directly into the host cell [7,8,9]. Understanding these mechanisms could help to identify targets for inhibition of OMV-associated toxin delivery and lead to attenuation of bacterial infections, as well as helping to achieve their therapeutic potential in medicine, via vaccines and engineered delivery vehicles [12,13,14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
