Vibrio cholerae Outer Membrane Vesicles Inhibit Bacteriophage Infection

Abstract

Novel preventatives could help in efforts to limit infection and the spread of cholera. Bacteriophage (or phage) treatment has been proposed to be an alternative intervention, given the rapid replication of virulent phages, prey specificity, and relative ease of finding new virulent phages. Phage tropism is dictated in part by the presence of phage receptors on the bacterial surface. While many phages that can kill have been isolated, whether this pathogen is able to defend itself by neutralizing phage binding is unknown. Here we show that secreted outer membrane vesicles (OMVs) act as a defense mechanism that confers protection to against phage predation and that this OMV-mediated inhibition is phage receptor-dependent. Our results suggest that phage therapy or prophylaxis should take into consideration the production of OMVs as a bacterial decoy mechanism that could influence the outcome of phage treatment. Phages have been increasingly realized for the significance of their interactions with bacterial cells in multiple environments. Bacteria use myriad strategies to defend against phage infection, including: restriction modification, abortive infection, phase variation of cell surface receptors, phage-inducible chromosomal islands, and CRISPR-Cas systems. The data presented here suggest that the apparently passive process of OMV release can also contribute to phage defense. By considering the effect of OMVs on infection of by three unique virulent phages, ICP1, ICP2 and ICP3, we show that, a reproducible reduction in bacterial killing is both dose- and phage receptor-dependent. This work supports a role for OMVs as natural decoys to defend bacteria from phage predation.

PQS Produced by the Pseudomonas aeruginosa Stress Response Repels Swarms Away from Bacteriophage and Antibiotics

“…This long-range stress response complements the short-range kin lysis stress system previously reported in P. aeruginosa (54). PQS activates heightened stress responses in P. aeruginosa, including the formation of outer membrane vesicles, which interfere with cytokine production and deliver toxins to target host cells (55)(56)(57). Through activation of the PqsR receptor, PQS also induces pqsE expression, which synthesizes a QS molecule that activates RhlR and is thereby responsible for regulation of key virulence factors that kill plants and animals, including hydrogen cyanide and elastase (41,58,59).…”

“…In natural environments, the stress response could mitigate the spread of phage infection throughout a population and thereby serve as a bacterial defense mechanism against phage to complement other defenses, including the CRISPR-Cas system (60). In particular, membrane vesicles function as phage decoys, and their production is upregulated in response to PQS in P. aeruginosa (56,57,61). Thus, the production of PQS and membrane vesicles in response to phage infection could function as a mechanism to increase transient immunity to phage.…”

Niche adaptation limits bacteriophage predation of Vibrio cholerae in a nutrient-poor aquatic environment

“…We show that ICP3 is able to attach to V. cholerae but is incapable of replicating in fresh or estuary water, and the majority becomes inactive after a short period of time. ICP3 when bound to outer membrane vesicles cannot inject its DNA and 90% of bound ICP3 shows a full capsid (30). T7 DNA ejection needs active transport into the bacterial host that is mediated by the host RNA polymerase (31).…”

“…V. cholerae HC1037, a O1 El Tor clinical isolate (30) was grown in LB Miller broth or LB Miller agar plates at 37°C. Fresh water was collected from Massapoag Lake in MA, USA.…”

Viral metagenomic analysis of the cheese surface: a comparative study of rapid procedures for extracting virus-like particles

“…In the bacterial domain, they have multifaceted roles including the delivery of autolysins, cytotoxins and virulence factors, as well as nucleic acids (34, 35). In our membrane vesicle sample, DNA sequencing leads us to formulate several suppositions: i) since half of vesicle reads map to contigs classified as potential phages, it may be that Epoisses membrane vesicles serve as decoys and trap phages, as recently reported in Vibrio cholerae (36). The interaction between phage tail fibers and membrane vesicles harboring proper phage receptors could contribute to the emptying, and thereby inactivating of phage virions, after DNA injection.…”