Viruses don’t only infect animals. Some, called bacteriophages, can infect bacteria. As we learn more about the bacteria that humans carry in their gut, and how important that microbial community is to our health, scientists want to know more about how to manipulate those microbes to improve health. It may be possible to use bacteriophages for that purpose. While ingesting viruses may not seem like a therapy, scientists at Colorado State University have found that a special cocktail of bacteriophages they created is safe for people and can reduce harmful gut inflammation.
This work, which has been reported in the Journal of the American College of Nutrition, suggested that this method can encourage the growth of good bacteria that keep the gut, and immune function, healthy. At the same time, it lowers the level of bad bacteria that can cause inflammation, like Escherichia coli. This work may also open up new avenues to fighting specific bacterial pathogens, instead of using antibiotics that can destroy bad, and good bacteria.
"If you told someone to go eat viruses for a month, they'd probably say you're crazy," said study co-investigator Tiffany Weir, an associate professor in CSU's Department of Food Science and Human Nutrition. "Bacteriophages are pretty cool because their host range is so specific that you're not going to get sick from them. The ones we used infect E. coli cells and cause them to explode."
Watch E. coli getting destroyed by bacteriophages in the video by Nanolive.
"People taking antibiotics can develop resistance and experience gastrointestinal distress since antibiotics kill both bad and good bacteria in the gut," said study co-investigator Taylor C. Wallace, principal and CEO of the Think Healthy Group Inc. and professor in the Department of Nutrition and Food Studies at George Mason University. "Using bacteriophages that infect only specific types of bacteria spares the many good bacteria in the gut that are linked to numerous long-term beneficial health outcomes. We have shown for the first time that bacteriophage treatment has no apparent side effects in humans, at least with short-term use."
Scientists began fighting microbes with bacteriophages in the early 1900s, but finding the right phage to kill a specific pathogen was, for them, an impossible task. They found antibiotics did the job effectively and abandoned the phage approach. As our knowledge of the human microbiome expanded, research focus turns back toward those phages, and the first clinical study in the US to assess the effects of bacteriophages in patients, The Bacteriophage for Gastrointestinal Health (PHAGE) Study, was launched.
The PHAGE study ran from 2016 to 2017 at CSU's Human Performance Clinical Research Laboratory; 36 participants that did not have a diagnosed disease but did experience symptoms like diarrhea, gas or bloating - occasional gastrointestinal distress - were enrolled. One group received a placebo while the other got the phage cocktail for four weeks. The participants then went two weeks with no treatment, then went through the opposite treatment for the remaining four weeks. The scientists were trying to target E. coli in the gut for destruction.
"We used a combination of four strains to prevent the bacteria from developing resistance to the phages," Weir noted.
The participants did well on the phage treatment, reporting no adverse effects. A protein linked to inflammation, interleukin 4, was significantly reduced. The bacterial populations in the gut remained stable while E. coli levels went down.
Phages, suggested the researchers, may be useful for treating diseases as well as the nutritional deficits that are caused by chronic diarrhea.
"With the current interest in modifying the gut bacteria for improved health, people are beginning to seriously look at phages again for the first time in nearly 100 years," Weir said.
A facility for bacteriophage research has been opened at the University of California, San Diego. Learn more about recent microbiology news and the phage center (which is discussed around minute 31) from the video above by the American Society for Microbiology.