Bacteriophage adhering to mucus provide a non-host-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, Forest Rohwer

Research output: Contribution to journalArticleResearchpeer-review

350 Citations (Scopus)

Abstract

Mucosal surfaces are a main entry point for pathogens and the principal sites of defense against infection. Both bacteria and phage are associated with this mucus. Here we show that phageto- bacteria ratios were increased, relative to the adjacent environment, on all mucosal surfaces sampled, ranging from cnidarians to humans. 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. In particular, phage Ig-like domains bind variable glycan residues that coat the mucin glycoprotein component of mucus. Metagenomic analysis found these Ig-like proteins present in the phages sampled from many environments, particularly from locations adjacent to mucosal surfaces. Based on these observations, we present the bacteriophage adherence to mucus model that provides a ubiquitous, but non-host-derived, immunity applicable to mucosal surfaces. The model suggests that metazoan mucosal surfaces and phage coevolve to maintain phage adherence. 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.
Original languageEnglish
Pages (from-to)10771-10776
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume110
Issue number26
DOIs
Publication statusPublished - 25 Jun 2013
Externally publishedYes

Keywords

  • Host-pathogen
  • Immune system
  • Immunoglobulin
  • Symbiosis
  • Virus

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