Murine Norovirus Interaction with Enterobacter cloacae Leads to Changes in Membrane Stability and Packaging of Lipid and Metabolite Vesicle Content

An in-depth exploration of the multifaceted roles of EVs in the context of pathogenic single-cell microorganisms

SUMMARYExtracellular vesicles (EVs) have been recognized throughout scientific communities as potential vehicles of intercellular communication in both eukaryotes and prokaryotes, thereby influencing various physiological and pathological functions of both parent and recipient cells. This review provides an in-depth exploration of the multifaceted roles of EVs in the context of bacteria and protozoan parasite EVs, shedding light on their contributions to physiological processes and disease pathogenesis. These studies highlight EVs as a conserved mechanism of cellular communication, which may lead us to important breakthroughs in our understanding of infection, mechanisms of pathogenesis, and as indicators of disease. Furthermore, EVs are involved in host-microbe interactions, offering insights into the strategies employed by bacteria and protozoan parasites to modulate host responses, evade the immune system, and establish infections.

Changes in lipid composition of host-derived extracellular vesicles following Salmonella infection

IMPORTANCE

This study delves into the previously unexplored territory of extracellular vesicle (EV) cargo and composition, specifically focusing on lipid composition changes in EVs following Salmonella infection. EVs play crucial roles in intercellular communication, carrying a variety of biomolecules. Investigating how these EV cargo lipids change post-infection with Salmonella is significant for understanding the molecular mechanisms underlying lipid trafficking during infection. Given the impact of lipid composition on EV function, this research uncovers distinct differences in the lipid profiles of EVs at different time points post-infection and between infected and uninfected macrophages. This study identified lipids that are differentially abundant in EVs produced by the host during infection, offering novel insights into the dynamics of lipid profiles in EVs during cellular processes and infections. This work advances our understanding of host-pathogen interactions, specifically lipid-mediated EV functions during infection.

Comparison of Methods for Quantifying Extracellular Vesicles of Gram-Negative Bacteria

There are a variety of methods employed by laboratories for quantifying extracellular vesicles isolated from bacteria. As a result, the ability to compare results across published studies can lead to questions regarding the suitability of methods and buffers for accurately quantifying these vesicles. Within the literature, there are several common methods for vesicle quantification. These include lipid quantification using the lipophilic dye FM 4-64, protein quantification using microBCA, Qubit, and NanoOrange assays, or direct vesicle enumeration using nanoparticle tracking analysis. In addition, various diluents and lysis buffers are also used to resuspend and treat vesicles. In this study, we directly compared the quantification of a bacterial outer membrane vesicle using several commonly used methods. We also tested the impact of different buffers, buffer age, lysis method, and vesicle diluent on vesicle quantification. The results showed that buffer age had no significant effect on vesicle quantification, but the lysis method impacted the reliability of measurements using Qubit and NanoOrange. The microBCA assay displayed the least variability in protein concentration values and was the most consistent, regardless of the buffer or diluent used. MicroBCA also demonstrated the strongest correlation to the NTA-determined particle number across a range of vesicle concentrations. Overall, these results indicate that with appropriate diluent and buffer choice, microBCA vs. NTA standard curves could be generated and the microBCA assay used to estimate the particle number when NTA instrumentation is not readily available.

Roles of bacterial extracellular vesicles in systemic diseases

Accumulating evidence suggests that in various systems, not all bidirectional microbiota-host interactions involve direct cell contact. Bacterial extracellular vesicles (BEVs) may be key participants in this interkingdom crosstalk. BEVs mediate microbiota functions by delivering effector molecules that modulate host signaling pathways, thereby facilitating host-microbe interactions. BEV production during infections by both pathogens and probiotics has been observed in various host tissues. Therefore, these vesicles released by microbiota may have the ability to drive or inhibit disease pathogenesis in different systems within the host. Here, we review the current knowledge of BEVs and particularly emphasize their interactions with the host and the pathogenesis of systemic diseases.

Unraveling the interplay between norovirus infection, gut microbiota, and novel antiviral approaches: a comprehensive review

Norovirus infection is a leading cause of acute gastroenteritis worldwide and can also cause harmful chronic infections in individuals with weakened immune systems. The role of the gut microbiota in the interactions between the host and noroviruses has been extensively studied. While most past studies were conducted in vitro or focused on murine noroviruses, recent research has expanded to human noroviruses using in vivo or ex vivo human intestinal enteroids culture studies. The gut microbiota has been observed to have both promoting and inhibiting effects on human noroviruses. Understanding the interaction between noroviruses and the gut microbiota or probiotics is crucial for studying the pathogenesis of norovirus infection and its potential implications, including probiotics and vaccines for infection control. Recently, several clinical trials of probiotics and norovirus vaccines have also been published. Therefore, in this review, we discuss the current understanding and recent updates on the interactions between noroviruses and gut microbiota, including the impact of norovirus on the microbiota profile, pro-viral and antiviral effects of microbiota on norovirus infection, the use of probiotics for treating norovirus infections, and human norovirus vaccine development.