Scientists have identified more than 140,000 previously unknown viruses that live in the human intestine. But how they affect our body remains a mystery. A virus database created by scientists will help solve this problem in the future.
The gut microbiome, or the community of bacteria that is found in the human digestive system, plays an important role in the digestion of food and the regulation of the immune system. But many studies have also linked imbalances in gut microbes to liver disease, obesity, and allergies.
However, surprisingly little is known about the microbiome at all. Although the microbiome includes many microorganisms, including bacteria and viruses, previous research has focused primarily on gut bacteria. The point is, they are much easier to spot.
In the new study, a team of researchers used metagenomics to identify viruses. It includes the analysis of the entire genetic material of the bacterial community and the subsequent comparison of the found individual sequences with specific species. They analyzed more than 28,000 gut microbiome samples from people from 28 countries.
In the course of this process, the complete genomes of more than 140 thousand types of viruses inhabiting the human intestine were identified. However, it is worth noting that one person carries only a small portion of these species.
Basically, the intestines are inhabited by bacteriophages, or phages. These are viruses that selectively infect bacterial and archaeal cells. Most often, bacteriophages multiply inside bacteria and cause their lysis. As a rule, a bacteriophage consists of a protein coat and a single-stranded or double-stranded nucleic acid genetic material.
The researchers limited their capabilities to bacteriophages, as they sought to find out their role in human health. Most of them are not harmful to humans and are simply an integral part of the microbiota of our body, but perhaps their functions do not end there.
Phages can play a central role in the gut microbiome – for example, providing beneficial properties to their bacterial hosts and influencing how these bacteria develop.
Since bacterial communities are a critical component of our gut, it is not hard to imagine that phages could play a key role in maintaining a healthy balance in the human gut. However, there are cases when phages contributed to the development of the disease. For example, diphtheria, a serious bacterial infection, and botulism, a serious disease that affects the body’s nerves. The disease is caused by toxins that are encoded by phage genes.
In an interview with Live Science, the scientists said they had published the genomes of viruses that invaded bacteria in a new database they created called the Intestinal Phage Database. Scientists said it could be used to conduct further research on these viruses.