By analyzing the viral component of the intestinal microbiota, researchers have discovered over 33,000 different viral populations. This makes the composition of each individual’s microbiota unique.
It is not only our fingerprints or our DNA that are unique, but also our virome, the viral component of the intestinal microbiota. This is the discovery made by researchers at Ohio State University. In their study, which was published in the journal Cell Host & Microbe and which aims to build a comprehensive database of virus populations in the human digestive system, the researchers analyzed viruses from the intestines of 1,986 healthy and sick people in 16 Western countries. They were able to identify 33,242 unique virus populations, most of which are completely harmless.
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A Bacteriophage
“We have created a solid starting point to see what the virome looks like in humans,” says Olivier Zablocki, a post-doctoral researcher in microbiology and co-author of the study. If we can characterize the viruses that keep us healthy, we could use this information to design future therapies for pathogens that cannot be treated with drugs”.
A unique viral signature
Based on a careful analysis of 32 studies of intestinal viruses over a period of ten years, researchers have found that although some virus populations are distributed among a subgroup of humans, there is no common core group of intestinal viruses for all humans.
Their work is even more difficult because, unlike bacteria, viruses are difficult to detect because their genome does not contain a common signature gene sequence. “We used machine learning about known viruses to help us identify unknown viruses,” says Ann Gregory, the lead author of the paper.
Viruses to fight multi-resistant bacteria
Although there is no common group of viruses, researchers have identified trends. For example, age in healthy Western people influences the diversity of viruses in the intestine, which increases dramatically from infancy to adulthood, and which drops after the age of 65.
People living in non-Western countries have a greater diversity of intestinal viruses than people living in the West. This suggests that diet and environment are responsible for the differences in the virome.
“A general rule of ecology is that greater diversity leads to a healthier ecosystem,” says Gregory. We know that a greater diversity of viruses and microbes is usually associated with a healthier individual. And we’ve seen that healthy people tend to have a greater variety of viruses, indicating that these viruses have the potential to do something positive and play a useful role.
For researchers, this finding gives hope that viruses could soon represent a new class of drugs to combat pathogenic bacteria, especially those that have developed resistance to antibiotics. A better understanding of the viruses in the intestinal environment could also improve our understanding of the gastrointestinal symptoms experienced by some of the most affected patients with COVID-19. “They could also provide the basis for something that we could use in the oceans to combat climate change,” says Matthew Sullivan, Professor of Microbiology and co-author of the study.
References
Gregory, A. C., Zablocki, O., Zayed, A. A., Howell, A., Bolduc, B., & Sullivan, M. B. (2020). The Gut Virome Database reveals age-dependent patterns of virome diversity in the human gut. Cell Host & Microbe, 28(5), 724–740.e8. https://doi.org/10.1016/j.chom.2020.08.003
