Scientists recently described a new form of symbiosis at our mucosal sites with an unassuming partner: bacteriophage. In a paper published in PNAS, Jeremy Barr and colleagues noticed that phage are enriched at mucosal surfaces compared to surrounding surfaces and demonstrated that a specific interaction between Ig-like domains on the phage capsid and mucin glycans is what holds them in place. Their findings suggest that the presence of phage in mucin protects the underlying epithelial cells from bacterial infection, a good reason for us to have evolved to keep them there. The relationship benefits the phage too – mucosal sites are a buffet of bacteria for the phage to infect and multiply within.
Join us at the Pheonix next Friday May 31st at 1 PM for a discussion over drinks about our friendly phage.
Here are some reasons we chose this paper and a few things to think about for discussion:
• It’s important to consider the diversity of microorganisms in our microbiome and their interactions with each other and the host in order to understand the ecosystem. Given phage specificity for certain bacterial species, does our virome change with fluctuations in bacterial communities? How does this alter community dynamics? (Interesting read on virome research: The other microbiome)
• We’ve coerced bacteriophage to act as our microscopic army against invading pathogens. It’s a strategy that not only humans, but also other metazoans with mucosal sites use as a strategy to defend against infection. But bacteria are smart too and aren’t content with the short end of the stick. They have their own defense against phages – the CRISPR/Cas systems. Recently this system is also implicated in bacterial virulence and immune evasion. Have our friendly phage contributed to pathogen evolution?
If you’re not able to make it, but are equally as fascinated with our inner viromes as we are, check out these links for more info and check back for a follow-up post on our discussion.
Carl Zimmer, The Loom: Meet your new symbionts: Trillions of Viruses
Ed Yong, Nature News: Viruses in the gut protect from infection
Story behind the paper by Jeremy Barr, The Tree of Life
Bacteriophage Paper: Barr, J. J. et al. Proc. Natl. Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1305923110 (2013)