Babies walk around with more than 200 previously unknown viral families inside their intestines. This large number surprises researchers from the University of Copenhagen and COPSAC, who closely studied the nappies of 647 Danish babies and did the first mapping of its kind. It is very likely that these viruses play an important role in protecting children against chronic diseases.
Viruses are generally associated with disease. But our bodies are full of bacteria and viruses that constantly proliferate and interact with each other in our gastrointestinal tract. While we’ve known for decades that gut bacteria in young children are vital to protecting them from chronic disease later in life, our knowledge of the many viruses found there is minimal.
A few years ago, this gave University of Copenhagen professor Dennis Sandris Nielsen the idea to delve further into this question. As a result, a team of researchers from COPSAC (Copenhagen Prospective Studies on Asthma in Childhood) and the UCPH Department of Food Sciences, among others, spent five years studying and mapping the contents of the diapers of 647 healthy Danish children from one year.
“We found an exceptional number of unknown viruses in the feces of these babies. Not just thousands of new virus species, but to our surprise, the viruses represented more than 200 virus families yet to be described. This means that, from the beginning In life, healthy children are faced with an extreme diversity of intestinal viruses, which are likely to have a major impact on the development of various diseases later in life,” says Professor Dennis Sandris Nielsen from the Department of Food Sciences, lead author of the research paper on the study, now published in microbiology of nature.
The researchers found and mapped a total of 10,000 viral species in the children’s feces, a number ten times greater than the number of bacterial species in the same children. These viral species are distributed in 248 different viral families, of which only 16 were previously known. The researchers named the remaining 232 unknown viral families after the children whose diapers made the study possible. As a result, new viral families include names like sylvesterviridae, Rigmorviridae and Tristanviridae.
Bacterial viruses are our allies
“This is the first time that such a systematic overview of intestinal viral diversity has been compiled. It provides an entirely new basis for discovering the importance of viruses to our microbiome and immune system development. We hypothesize that, because the immune system has not yet learned to separate the wheat from the chaff by the age of one year, an extraordinarily high species richness of intestinal viruses emerges, and is likely needed to protect against chronic diseases such as asthma and diabetes more later in life,” says Shiraz Shah, first author and COPSAC Principal Investigator.
Ninety percent of the viruses found by researchers are bacterial viruses, known as bacteriophages. These viruses have bacteria as hosts and do not attack children’s own cells, which means they do not cause disease. The hypothesis is that bacteriophages serve primarily as allies:
“We work from the assumption that bacteriophages are largely responsible for shaping bacterial communities and their function in our intestinal system. Some bacteriophages can provide their host bacterium with properties that make it more competitive by integrating its own genome. in the bacterium’s genome. When this occurs, a bacteriophage can increase a bacterium’s ability to absorb, for example, various carbohydrates, allowing the bacterium to metabolize more stuff,” explains Dennis Sandris Nielsen, who continues:
“It also appears that bacteriophages help maintain the balance of the gut microbiome by controlling individual bacterial populations, ensuring there aren’t too many bacterial species in the ecosystem. It’s a bit like lion and gazelle populations in the savannah.”
Shiraz Shah adds:
“Previously, the research community focused primarily on the role of bacteria in relation to health and disease. But viruses are the third leg of the stool, and we need to learn more about them. It’s very likely that viruses, bacteria and the immune system interact and affect each other in some kind of balance. Any imbalance in this relationship likely increases the risk of chronic disease.”
The remaining ten percent of viruses found in children are eukaryotic, that is, they use human cells as hosts. These can be both friends and enemies for us:
“It’s sobering that every child is running around with 10-20 of these types of viruses that infect human cells. So there’s a constant viral infection, which doesn’t seem to make them sick. We only know very little about what’s really going on.” at play. I suppose they are important for training our immune systems to recognize infections later. But it may also be that they are a risk factor for diseases that we have yet to discover,” says Dennis Sandris Nielsen.
Could play an important role in inflammatory diseases
Researchers have yet to figure out where the many viruses in one-year-olds come from. Your best answer so far is environment:
“Our intestine is sterile until we are born. During birth, we are exposed to bacteria from the mother and from the environment. It is likely that some of the first viruses arrive along with these initial bacteria, while many others are introduced later to through dirty fingers, pets, dirt children put in their mouths, and other things in the environment,” says Dennis Sandris Nielsen.
As Shiraz Shah points out, the entire field of research speaks to a huge global health problem:
“Much research suggests that most of the chronic illnesses we’re familiar with, from arthritis to depression, have an inflammatory component. That is, the immune system isn’t working as it should, which could be because it wasn’t properly trained.” So if we learn more about the role that bacteria and viruses play in a well-trained immune system, it can hopefully lead us to being able to avoid many of the chronic diseases that afflict so many people today.”
Research groups have begun to investigate the role of intestinal viruses in relation to a number of different diseases that occur in childhood, such as asthma and ADHD.
ABOUT BACTERIOPHAGES
- There are generally two types of bacteriophages. Virulent bacteriophages take over the bacteria and produce 30 to 100 new virus particles inside. After this, the bacterial cell explodes from the inside and the new virus particles escape into the environment. Virulent bacteriophages help maintain the balance of the intestinal ecosystem.
- So-called temperate bacteriophages can reproduce by integrating their genetic material into the genome of the host bacterial cell. When the cell divides, so does the bacteriophage. Temperate bacteriophages help transfer new genes to the bacterium to make it more competitive. However, there are also studies suggesting that an imbalance in the temperate bacteriophage population is associated with various diseases, eg inflammatory bowel disease.
ABOUT VIRUSES
- A virus is a microorganism consisting of a genome, either DNA or RNA, encapsulated in a protein membrane. Viruses cannot multiply. Instead, a virus attacks a host cell, which it uses to make copies of itself.
- Viruses are classified into viral families, which are further divided into a larger number of viral genera and viral species. A better-known example of a viral family is the coronavirus, which includes the Covid-19, MERS, SARS, and various common cold viruses.