Bacteriophage adhering to mucus provide a non–host-derived immunity

Barr, Jeremy J.; Auro, Rita; Furlan, Mike; Whiteson, Katrine; Erb, Marcella L.; Pogliano, Joe; Stotland, Aleksandr; Wolkowicz, Roland; Cutting, Andrew S.; Doran, Kelly S.; Salamon, Peter; Youle, Merry; Rohwer, Forest

doi:10.1073/pnas.1305923110

Cited by 768 publications

(765 citation statements)

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“…Our initial BAM model proposed that the enrichment of phages in mucosal surfaces depended on the binding of the Ig-like Hoc proteins exposed on T4 phage capsids to mucin glycans (11). Thus, the difference in antimicrobial effect observed here might be a result of T4 phage accumulating to a higher abundance or persisting longer within the mucus layer.…”

Section: Resultsmentioning

confidence: 85%

“…Subsequently, we demonstrated that the Hoc proteins exposed on the T4 capsid bind to the mucin glycoproteins (11). The Hoc-bearing phages were enriched in mucus, reduced the bacterial load, and protected the underlying epithelial cells from infection, effects that we attributed to the putative mucin-binding activity of the Hoc protein (11). However, T4 and T4Δhoc phage particles also carry different capsid charges, as evidenced by their different electrophoretic mobilities (38).…”

Section: Discussionmentioning

confidence: 99%

“…Concurrently, the mucus is degraded by microbial proteases and subjected to shear forces that cause sloughing of the outermost layer (10). Despite this constant outward flux, in a diverse array of animals, phages are enriched on the mucosal surfaces compared with the surrounding milieu (11,12). Previous in vitro experiments using a T4 phage model (particle size ∼200 nm) demonstrated that this phage adhered to mucus via weak binding between Ig-like domains of the highly antigenic outer capsid protein (Hoc) and the abundant glycans of the mucin glycoproteins (11,12).…”

mentioning

confidence: 99%

“…Despite this constant outward flux, in a diverse array of animals, phages are enriched on the mucosal surfaces compared with the surrounding milieu (11,12). Previous in vitro experiments using a T4 phage model (particle size ∼200 nm) demonstrated that this phage adhered to mucus via weak binding between Ig-like domains of the highly antigenic outer capsid protein (Hoc) and the abundant glycans of the mucin glycoproteins (11,12). Moreover, T4 phage adhering to the mucus layer of tissue culture cells protected the underlying epithelium from bacterial infection.…”

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confidence: 99%

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Subdiffusive motion of bacteriophage in mucosal surfaces increases the frequency of bacterial encounters

Barr

Auro

Sam-Soon

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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181

186

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Bacteriophages (phages) defend mucosal surfaces against bacterial infections. However, their complex interactions with their bacterial hosts and with the mucus-covered epithelium remain mostly unexplored. Our previous work demonstrated that T4 phage with Hoc proteins exposed on their capsid adhered to mucin glycoproteins and protected mucus-producing tissue culture cells in vitro. On this basis, we proposed our bacteriophage adherence to mucus (BAM) model of immunity. Here, to test this model, we developed a microfluidic device (chip) that emulates a mucosal surface experiencing constant fluid flow and mucin secretion dynamics. Using mucus-producing human cells and Escherichia coli in the chip, we observed similar accumulation and persistence of mucus-adherent T4 phage and nonadherent T4Δhoc phage in the mucus. Nevertheless, T4 phage reduced bacterial colonization of the epithelium >4,000-fold compared with T4Δhoc phage. This suggests that phage adherence to mucus increases encounters with bacterial hosts by some other mechanism. Phages are traditionally thought to be completely dependent on normal diffusion, driven by random Brownian motion, for host contact. We demonstrated that T4 phage particles displayed subdiffusive motion in mucus, whereas T4Δhoc particles displayed normal diffusion. Experiments and modeling indicate that subdiffusive motion increases phage-host encounters when bacterial concentration is low. By concentrating phages in an optimal mucus zone, subdiffusion increases their host encounters and antimicrobial action. Our revised BAM model proposes that the fundamental mechanism of mucosal immunity is subdiffusion resulting from adherence to mucus. These findings suggest intriguing possibilities for engineering phages to manipulate and personalize the mucosal microbiome.BAM | virus | mucus | subdiffusion | search strategy I n all animals, mucosal surfaces provide critical immunological services by both protecting against invading bacterial pathogens and supporting large communities of commensal microorganisms (1, 2). Being exposed to the environment, mucosal surfaces are also the infection sites for many important bacterial diseases, including acute diarrhea and cystic fibrosis in humans. This, combined with their accessibility, make mucosal surfaces attractive venues for phage therapy; that is, the use of bacteriophages (phages) to treat and clear bacterial infections (3,4). Clinical success so far has been erratic (5). The complexities and dynamics of the mucus layer are rarely considered, and the activity of phages therein is mostly unknown. Not surprisingly, phages effective in vitro do not consistently reduce mucosal bacterial host levels in vivo (6, 7). An understanding of the interactions between phages and their bacterial hosts within the relevant physiological environment is critical for consistent success of phage therapy applications.The multilayered mucus is composed primarily of gel-forming mucin glycoproteins that are continually secreted by the underlying epithelium (8). The mucin...

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Section: Resultsmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Subdiffusive motion of bacteriophage in mucosal surfaces increases the frequency of bacterial encounters

Barr

Auro

Sam-Soon

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

181

186

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“…Hypervariable domains, including C-type lectins, have been identified in gut-associated phages (15), suggesting that extracellular sequestration with binding to mucus or epithelial cell surface glycans could represent another potential mechanism. Barr et al found that enrichment of phages in mucus occurs through binding of Ig-like domains exposed on phage capsids to carbohydrate residues present in the mucin glycoprotein component of mucus, thereby creating a form of antimicrobial defense that could protect mucosal surfaces (16). COPRO-Seq analysis of cecal samples obtained from mice in the germ-free treatment group that lacked the 15-member artificial community and were gavaged with the live p-VLP preparation alone revealed no detectable phages in the cecum at the time of sacrifice (Dataset S1), supporting the notion that persistence of ϕHSC03-ϕHSC05 may be dependent upon the presence of bacteria.…”

Section: Nonsimultaneous Detection Of Viruses and Community Rearrangementioning

confidence: 99%

Gnotobiotic mouse model of phage–bacterial host dynamics in the human gut

Reyes

McNulty

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

308

269

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Bacterial viruses (phages) are the most abundant biological group on Earth and are more genetically diverse than their bacterial prey/ hosts. To characterize their role as agents shaping gut microbial community structure, adult germ-free mice were colonized with a consortium of 15 sequenced human bacterial symbionts, 13 of which harbored one or more predicted prophages. One member, Bacteroides cellulosilyticus WH2, was represented by a library of isogenic transposon mutants that covered 90% of its genes. Once assembled, the community was subjected to a staged phage attack with a pool of live or heat-killed virus-like particles (VLPs) purified from the fecal microbiota of five healthy humans. Shotgun sequencing of DNA from the input pooled VLP preparation plus shotgun sequencing of gut microbiota samples and purified fecal VLPs from the gnotobiotic mice revealed a reproducible nonsimultaneous pattern of attack extending over a 25-d period that involved five phages, none described previously. This system allowed us to (i) correlate increases in specific phages present in the pooled VLPs with reductions in the representation of particular bacterial taxa, (ii) provide evidence that phage resistance occurred because of ecological or epigenetic factors, (iii) track the origin of each of the five phages among the five human donors plus the extent of their genome variation between and within recipient mice, and (iv) establish the dramatic in vivo fitness advantage that a locus within a B. cellulosilyticus prophage confers upon its host. Together, these results provide a defined community-wide view of phage-bacterial host dynamics in the gut.T he human gut is home to tens of trillions of microbial cells representing all three domains of life, although most are bacteria. These organisms collaborate and compete for functional niches and physical locations (habitats). Together, they form a continuously functioning microbial metabolic "organ." The microbial diversity, interpersonal variation, and dynamism of the human gut microbiota make the task of identifying the factors that define community configurations extremely challenging.In some ecosystems, phages maintain high bacterial strain level diversity through lysis of their host strains (constant diversity dynamics model; refs 1, 2). The resulting emptied niche is filled with either an evolved resistant bacterial strain or a taxonomically closely related bacterial species. These dynamics have been observed in open marine environments (1). In contrast, a recent study of 37 healthy adults indicated that a person's fecal microbiota was remarkably stable, with 60% of bacterial strains retained over the course of 5 y (3). Stability followed a power law dynamic that when extrapolated suggests that most strains in an individual's gut community are retained for decades (3). In a metagenomic analysis of virus-like particles (VLPs) purified from the fecal microbiota of healthy adult monozygotic twins and their mothers, sampled over the course of a year, viral community structure exh...

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The Human Intestinal Microbiota and Microbiome

Koren¹,

Ley²

2015

Yamada' S Textbook of Gastroenterology

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Bacteriophage adhering to mucus provide a non–host-derived immunity

Cited by 768 publications

References 72 publications

Subdiffusive motion of bacteriophage in mucosal surfaces increases the frequency of bacterial encounters

Subdiffusive motion of bacteriophage in mucosal surfaces increases the frequency of bacterial encounters

Gnotobiotic mouse model of phage–bacterial host dynamics in the human gut

The Human Intestinal Microbiota and Microbiome

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