In a paper published Monday in the journal Proceedings of the National Academy of Sciences, scientists say that bacteria in the gut can manufacture and use viruses as weapons against other rival bacteria in what the website LiveScience.com calls “intestinal shootouts.”
Raw Story spoke to Dr. Breck Duerkop of the Hooper Lab at University of Texas Southwestern Medical Center, the research team that authored the study. Duerkop, who was on Dr. Lora Hooper’s research team, said that while phages are among the most common organisms on earth and scientists have known of their existence in mammalian digestive tracts and oral cavities and on our skin for generations, it has been “very understudied” how exactly they have functioned in relation to their hosts.
“The bacteria we’re studying in the lab under standard culture conditions, when subject to certain environmental stressors will begin to produce viruses,” said Duerkop, stresses like the absence or abundance of certain nutrients, or, as most people have experienced, the presence of antibiotics. The shifts in the bacteria’s normal conditions give rise to competition for resources and sends species of bacteria to war, which is what can cause the stomach upset and diarrhea sometimes associated with taking antibiotics.
Researchers focused on Enterococcus faecalis, a bacterium found in the gut that is commonly associated with antibiotic-resistant hospital-acquired blood infections. Phages have woven their genetic code directly into that of E. faecalis, where they remain dormant until the system becomes stressed, at which point the bacteria begin to manufacture phages, which are their chemical weapons against other species.
“This phage confers benefit to its E. faecalis host by acting as a weapon against other E. faecalis strains that are competing for nutrients in the same intestinal niche,” Dr. Hooper told LiveScience. ”This is one of the first examples of intraspecies bacterial warfare in the intestinal ecosystem.”
According to Duerkop, phage-producing bacteria are fairly easy to grow in the lab and manipulate via genetics. He foresees a time when treatments could be administered to patients that fight infections in one of three ways.
“You could imagine genetically engineering bacteria with a remote control to produce a particular temperate phage [a phage capable of lying dormant in a bacteria cell] under a very specific condition at a very specific time,” said Duerkop, “that would release virus to target a particular pathogenic organism at a particular tissue site,” such as when the system is stressed or an invasive pathogen is detected.
Or scientists could also produce bacteriophages that are administered at the time of an active infection to fight hostile bacteria. Duerkop said that patients could potentially the treatment orally or even apply it topically to the skin.
Finally, when bacteria produce phages, the phages free themselves of the host cell using proteins called lysins. These lysins chemically match proteins produced by a wide range of bacteria, and their presence can inhibit other bacteria’s ability to release their own viral weapons, blocking a disease’s ability to spread in the body.
These treatment options point the way, researchers hope, to the next generation of anti-microbial medicines.
In June, scientists at the Brain-Body Institute at McMaster University in Ontario released a study that indicated that the health and diversity of microorganisms living in the gut could have a profound impact on hosts’ moods, perception and cognitive health. The Hooper team’s findings show that we may soon have a way to influence that balance, by choosing sides and stoking tiny, raging bacteriological wars.
David Ferguson is an editor at Raw Story. He was previously writer and radio producer in Athens, Georgia, hosting two shows for Georgia Public Broadcasting and blogging at Firedoglake.com and elsewhere. He is currently working on a book.
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