Is there an alternative to antibiotics?

Should all viruses be considered villains? Scientists have discovered that viruses heavily influence the microbiome and, if harnessed correctly, could offer a potential alternative to antibiotics.

The human gastrointestinal tract is often looked at from a bacterial point of view, although it should be noted that other microbes also have important functional contributions. We are very bacteria-centric when we consider the gut microbiota and only a few studies have looked at the viral component (or virome).

What is a virome?

Virome is the term referring to the entire viral genetic material present in a sample. Viruses are the most numerous biological entities on Earth, inhabiting diverse environments ranging from the oceans to hydrothermal vents and the human body.

The virome consists of the genomes of viruses and considerable effort is being made to characterise the genomes of human viruses and bacteriophages (also known as phages). It has been postulated that the number of unique genes coded in the virome may be immense, as it includes not only those of viruses that infect cells but also bacteriophages, retroviruses, fungi viruses and others.

Researchers have historically focused on eukaryotic viruses because of their well-known impact on human health, including the influenza virus that causes seasonal flu epidemics and the viruses that cause devastating health consequences like Ebola, SARS or the recent COVID-19.

Prokaryotic viruses

However, increasing evidence suggests that prokaryotic viruses (bacteriophages) can also impact human health by affecting the structure and function of the bacterial communities that symbiotically interact with humans.

In the healthy human gut, bacteriophages are much more abundant than animal cell viruses and prevail in the human gut virome where they exhibit great variability among different individuals or within the same individual over time.

In detail, bacteriophages — viruses that infect commensal bacteria — are important for microbiota modulation and have been proposed to be used for microbiota modulation by targeting specific commensal groups, which may have a profound impact on the immune response at the mucosa level.

For example, like bacteria and fungi, certain viruses can stimulate a low level of immune response. For these reasons, further research will likely elucidate some of the effects of the gut virome not only in host disease, but as beneficial modulators of gut physiology.

Biological control

Biological control, or simply biocontrol, is a new theory that supports the application of certain microorganisms or their products in the gut or other human organs to reduce the number of undesirable organisms. An example is administration of a Vibrio cholerae-specific phage cocktail protecting against cholera by reducing both colonisation and cholera-like diarrhoea.

Thus, prokaryotic viruses may be perceived as bacterial load controllers and might be used as a therapeutic means of intervention in the future as a biological substitute for antibiotic treatment.