An international team of scientists who studied the faeces of 647 Danish children for five years found something startling.
The diaper samples contained 10,000 types of viruses, ten times the number of types of bacteria in the same babies. Most viruses have not been previously described.
This may bother many readers. Viruses have not had a good reputation in recent years. But what many people don’t realize is that the vast majority of viruses don’t infect humans, and don’t infect humans or animals at all. The viruses I’m talking about are phages. It only infects bacteria and makes up the majority of the human microbiome.
In fact, about 90% of the viruses found in Danish diapers were bacteriostatic.
The human gut microbiome is a complex collection of microorganisms, including bacteria, archaea, microbial eukaryotes, and viruses. The viral or viral component of the gut microbiome consists primarily of phages that help maintain a healthy and diverse microbiome.
In this new study, researchers — a collaborative team from Denmark, Canada and France — looked at how many of the 10,000 new viruses count and how best to describe all this new viral diversity in an accessible way.
They created an “atlas of infant gut DNA virus diversity” by grouping viruses into new viral families and ranking them based on how similar their genomes are to each other. They found 248 families, of which only 16 were previously known.
The researchers named 232 recently identified virus families: Sylvesterviridae, Rigmorviridae and Tristanviridae. The interesting thing about phages and other viruses in the gut is that each person has their own unique combination, with little or no overlap between two different people.
While each intestinal virus is unique, it is also stable over time in adults, which means you carry the same set of viruses with you as you age. But immediately after the birth of a child, this virus is very different from an adult and stabilizes only after two years.
Comparing the nearly 10,000 viruses in this new study with large-scale control groups of healthy adults, the researchers found that only about 800 of these viruses had previously been detected.
This means that when children are born and the first phages colonize the intestine, not all “baby phages” remain there, but are gradually replaced by “adult phages”.
This substitution may be partly related to the bacterial host that these phages infect. For example, Bacteroides, Faecalibacterium and Bifidobacterium have been among the most putative hosts for phages in infants.
In contrast, the largest group of adult enterobacteria, members of the order Crassvirales, did not circulate in the faeces of children, which means that children acquire these phages as they grow older.
And with the addition of 10,000 new virus species and many new families from just one group of a few hundred Danish children, it’s clear that we don’t know more about the virus than we do.
The report was prepared by Evelyn Adriansens, Head of the Enterovirus and Virus Group, Quadram Institute.
Source: Science Alert
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