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A study identifies a new virus that lives in the human gut. Tom Werner/Getty Images
  • Scientists have broadly studied the identity and roles of human gut bacteria.
  • However, research into human gut viruses is lagging.
  • In a new study, scientists identify a new virus that may have an important influence on human health and disease.

Human gut microbiota, including bacteria, fungi, and viruses, are major players in human health.

Scientists have studied the effects of imbalances in gut bacteria extensively. Several conditions, including obesity, diabetes, cancer, inflammatory bowel disease, and neurological diseases, all have associations with an imbalance among these bacteria.

Although researchers are still working out the details, there is little doubt these microorganisms have an intricate link to health and disease.

Health experts know much less about the viruses, called gut virobiota, that exist within the human gut. A recent study that appears in mSystems investigated and identified numerous viral genomes present in humans worldwide.

Most viruses residing in the human gut are called bacteriophages, or phages. These viruses require a bacterial host to reproduce.

Scientists have linked this close association between bacteria and viruses to numerous diseases, such as liver disease and some forms of cancer.

“It is therefore important to shed more light on the virobiota, and their collective genomes referred to as the virome, as this will pave the way to unraveling the complex interactions within the gut microbiota and their effect on the human host,” state the authors of this study.

Studying the gut virome is no small feat. Phages appear to be quite diverse and somewhat unique in each individual, according to the study’s principal researcher Jelle Matthijnssens, Ph.D., a professor in the Laboratory of Viral Metagenomics at KU Leuven in Belgium.

The individuality of gut viromes appears to be influenced by geographical origin, age, diet, and health status.

In addition, gut virome is a relatively new area of study. Because this research is in its infancy, scientists have yet to identify and classify the majority of these phages.

The researchers analyzed 254 fecal samples from 204 Danish participants, comprising children and adolescents aged 6–18 years and adults aged 40–73 years. The study team used the Novel Enrichment Technique of Viromes protocol to purify the stool samples and sequence their genomes.

From this data, researchers developed the Danish Enteric Virome Catalog, or DEVoC. According to the authors, DEVoC is “the largest human gut virome catalog generated from consistently processed fecal samples.”

Using DEVoC, they compared 91 healthy gut viromes from the study population.

While most phage genomes were unique to individuals, 39 were present in more than 10 healthy participants. Three of the 39 most common genomes appeared to be associated with age.

The team then cross-referenced the study results with global virome data. Two of the 39 phage genomes — crAss-like phage and LoVEphage — showed remarkably high prevalence worldwide, at 20.6% and 14.4%, respectively.

The researchers identified one as a crAss-like phage belonging to the AlphacrAssvirinae subfamily, which also includes herpes simplex virus 1 and 2. The other was a previously undescribed phage, which they dubbed LoVEphage because it encodes “lots of viral elements.”

“Our finding of the widespread distribution of this novel phage raises interesting questions with respect to [phages’] role in the human gut microbiota and potential implications in human health and disease,” said Prof. Matthijnssens in an interview with Medical News Today. He continued:

“The vast majority of genes encoded by these novel phages have unknown functions, making it hard to predict how they could influence their bacterial host and the human host.”

MNT also spoke with Anthony William Maresso, Ph.D., a professor at Baylor College of Medicine in Houston, TX, about the study. He said:

“A strength of this study is the examination of viral signatures from many different subjects. It shows how the virome is somewhat individualized, much like what was found for the human microbiome project. There seems to be an association with age as well, and a new undescribed phage in high abundance was described.”

“In this field,” continued Prof. Maresso, “which is only scratching the surface, we are learning just how immeasurably complex and diverse is the total phage virome. The next frontier for this field will be the development of ways to harness the functional power of this cryptic genosphere to enhance our understanding of molecular medicine, cell biology, predator-prey ecology, and protein enzymology.”

Speaking about future research, Prof. Matthijnssens explained that “it would be very interesting to further screen human stool samples for the presence of this phage as well as their genetic relatives, and further characterize their interactions with their bacterial host.”

Studying the virome is still in its infancy, but fascinating discoveries are sure to exist just beyond the horizon.