Goin’ Viral: More on Phages and the Microbiome

I’m excited!  More to report to you this week about other parts of the biome!  Tuesday was all about macrobiome/microbiome teamwork; today, I’m focusing on the virome.

Researchers have found that certain bacteriophages (remember these are viruses that infect and kill bacteria, and are a normal part of our inner ecosystems) can kill pathogenic bacteria in specified places in the gut.  From my past posts on the subject, you may remember that scientists are looking for replacement treatments for antibiotics, which are non-specific and kill off good bacteria as well as bad, causing major disruptions to the biome.  (In this post, I give you a whole history of phage research, which is (finally) really starting to take off.)

Antibiotic resistant bacteria have become a serious threat in the industrialized world, as you know. While they can infect people without actually causing a problem, sometimes they can make their way to other organs (urinary tract, brain, blood, etc.) and cause massive infections in millions of people each year.   This team of scientists have shown that phages can be used to treat a type of antibiotic resistant infection in previous research:  now they wanted to see if they could kill the bacteria BEFORE it caused an infection.

To summarize: mucin, a major component of mucus, creates a layer between the microbes of the gut and the cells of the gut, and can make it hard for phages to kill bacteria.  However, some phages have evolved means of getting around the mucin to get at bacteria even in places where the mucin content is high.  The researchers screened sewage and animal feces to find phages that could kill bacteria in the presence of mucin and found one called ES17 that actually binds to mucin to increase its ability to infect bacteria.  In tests they found that indeed, ES17 could target and kill the particular antibiotic resistant bacteria they were using, meaning that the phage should be able to successfully kill pathogens even in deep areas of the gut where reservoirs of pathogens may be hiding, and do so before these bacteria can become problematic.  One of the researchers states, “We foresee the possibility that positional targeting will be the way smart drugs work in the future. Drugs won’t be just distributed all through the body in the hopes that some of it will end in the right spot. The drugs of the future will go only precisely where they are supposed to work. Our work with phages is the first case in which this has been achieved.”[i]

Awesome, right?

If you are interested in this topic, there is a fairly comprehensive article that was just published in The Scientist you might want to check out.[ii]  It’s too long to summarize in this post, but just a couple of highlights:

  1. Harvard researchers have shown (in a 2019 study) that phages “…not only directly affect the bacteria they infect in the mouse gut, but also influence the rest of the microbiome community via cascading effects on the chemical and biological composition of the gut.”
  2. Studies are have explored, and are continuing to look at, the role phages play in human diseases including Crohn’s, diabetes, and certain cancers.
  3. It turns out that like their larger co-inhabitants (bacteria, macrobiotic organisms, etc.) phages do interact directly with the immune system, activating both innate and adaptive immune response. Way more work needs to be done in this field.
  4. Love the last line of this article, and it’s a good ending for today’s post. Says one of the researchers who is studying phages, their immune  and multi-kingdom interactions, “…it’s a lot more complex than what we’d appreciated.”

Who does that sound like?!

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[i] https://www.eurekalert.org/pub_releases/2021-02/bcom-pca020521.php

[ii] https://www.the-scientist.com/features/are-phages-overlooked-mediators-of-health-and-disease-68364

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