Targeting of Mammalian Glycans Enhances Phage Predation in the Gastrointestinal Tract

The human mucosal surface consists of a eukaryotic epithelium, a prokaryotic microbiota, and a carbohydrate-rich interface that separates them. Bacteriophage parasitize the prokaryotes but are not known to associate with eukaryotic cells. In the gastrointestinal tract, the interaction of these two domains influences the health of the host, especially colonization with invasive pathobionts. Antibiotics may be used but they also kill protective commensals and lack the physio-chemical properties to be specifically and optimally active in this complex milieu. Here, we report a novel phage whose lytic cycle is enhanced in intestinal environments. The enhanced activity is encoded in its tail fiber gene, whose protein product binds human heparan sulfated proteoglycans and localizes the phage to the epithelial cell surface, thereby positioning it near its bacterial host, a type of locational targeting mechanism. This finding offers the prospect of developing epithelial-targeting phage to selectively remove invasive pathobiont species from mucosal surfaces. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=159 SRC="FIGDIR/small/212829v2_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@13219f6org.highwire.dtl.DTLVardef@469d7borg.highwire.dtl.DTLVardef@d31e0org.highwire.dtl.DTLVardef@458e14_HPS_FORMAT_FIGEXP M_FIG C_FIG Model showing (1) mucins from the intestinal mucus layer inhibit phage infection, (2) phage ES17 can bind to mucin and utilize other intestinal glycans as a receptor to infect and kill mucus-coated bacteria, and (3) phages like ES17 can be utilized to coat the intestinal epithelium by binding heparan sulfate glycans to protect from invasive pathogen infection.