Microbial Ecology in States of Health and Disease Workshop Summary (2014) / Chapter Skim
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A15 Bacteriophage adhering to mucus providea nonhost-derived immunity--Jeremy J. Barr, Rita Auro, Mike Furlan, Katrine L. Whiteson, Marcella L. Erb, Joe Pogliano, Aleksandr Stotland, Roland Wolkowicz, Andrew S. Cutting, Kelly S. Doran, Peter Salamon, Merry Youle, and Forest Rohwer
A15 Bacteriophage adhering to mucus providea nonhost-derived immunity--Jeremy J. Barr, Rita Auro, Mike Furlan, Katrine L. Whiteson, Marcella L. Erb, Joe Pogliano, Aleksandr Stotland, Roland Wolkowicz, Andrew S. Cutting, Kelly S. Doran, Peter Salamon, Merry Youle, and Forest Rohwer
Pages 383-400
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From page 383... ...
In vitro studies of tissue culture cells with and without surface mucus demonstrated that this increase in phage abundance is mucus dependent and protects the underlying epithelium from bacterial infection. Enrichment of phage in mucus occurs via binding interactions between mucin glycoproteins and Ig-like protein domains exposed on phage capsids.
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From page 384... ...
This benefits the metazoan host by limiting mucosal bacteria, and benefits the phage through more frequent interactions with bacterial hosts. The relationships shown here suggest a symbiotic relationship between phage and metazoan hosts that provides a previously unrecognized antimicrobial defense that actively protects mucosal surfaces.
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From page 385... ...
model whereby phages provide a non– host-derived antimicrobial defense on the mucosal surfaces of diverse metazoan hosts. Results Phage Adhere to Mucus Our preliminary investigations of mucosal surfaces suggested that phage concentrations in the mucus layer were elevated compared with the surrounding
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From page 386... ...
(C) Phage adherence to uncoated agar plates and agar coated with mucin, DNA, or protein (n = 12, t = 5.306, *
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From page 387... ...
Phage Adherence and Bacterial Infection The mucus layer is an optimal environment for microbial growth, providing structure as well as nutrients in the form of diverse, mucin-associated glycans. To limit this growth, the metazoan host retards microbial colonization by diverse antimicrobial mechanisms (Phalipon et al., 2002; Raj and Dentino, 2002; Schluter and Foster, 2012; Vaishnava et al., 2011)
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Cells then were scraped from the plates and the attached bacteria were fluorescently stained and counted by epifluorescence microscopy. Phage pretreatment of mucus-producing TC cell lines (T84, A549)
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T4 phage pretreatment significantly decreased subsequent bacterial adherence to mucus-producing TC cell lines (T84: n > 30, t = 32.05, *
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Second, a competition assay using hoc+ and hoc– T4 phage and mucusproducing TC cells was performed to demonstrate the role of mucin in phage adherence. Phage suspended in mucin solutions ranging from 0% to 5% (wt/vol)
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From page 391... ...
Thus, all three of these experimental approaches supported our hypothesis that the Hoc proteins displayed on the T4 phage capsid interact with mucin. Phage Capsid Ig-Like Domains Interact with Glycans It is known that ∼25% of sequenced tailed dsDNA phages (Caudovirales)
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The hoc+ T4 phage adhered to many diverse glycans and showed a preference for the O-linked glycan residues typically found in mucin glycoproteins (Figure A15-4B, SI Materials and Methods, and Table S2)
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In vivo, similar phage binding to mucin glycans would increase phage residence time in mucus layers. Because bacterial concentrations typically are enriched in mucus (Fig.
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(4) Mucus-adherent phage are more likely to encounter bacterial hosts, thus are under positive selection for capsid proteins that enable them to remain in the mucus layer.
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Through such mechanisms, we envision that adherent lytic phages provide a dynamic and adaptable defense for their metazoan hosts -- a unique example of a metazoan–phage symbiosis. We posit that BAM immunity reduces bacterial pathogenesis and provides a previously unrecognized, mucosal immunity.
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From page 396... ...
The number of adherent phage was calculated from the number of plaque-forming units observed multiplied by the initial phage dilution. To determine whether ucus macro olecules directly affected phage infectivity, hoc+ and hoc– T4 m m phage (109 pfu·mL−1)
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From page 397... ...
Cells were scraped from plates, and adherent phage and bacteria were counted by either epifluorescence microscopy, as described above, or colony-forming and plaque-forming units. Then, 100 μL of a relevant dilution was spread onto an agar plate and incubated overnight at 37°C, and the number of adherent bacteria was calculated from the colonyforming units observed multiplied by the initial dilution.
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From page 398... ...
Proc Natl Acad Sci USA 110(12)
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From page 399... ...
Proc Natl Acad Sci USA 107(2)
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Evolutionary transitions in bacterial symbiosis. Proc Natl Acad Sci USA 108(Suppl 2)
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