Our traditional view of viruses has been narrowly perceived to that their sole role is as organic aggressors. Certainly, their visible effect upon our human history, at least until now, has only been understood as the source of myriad scourges throughout human history. Viral epidemics have accounted for an enormous number of deaths including measles, smallpox, chickenpox, influenza, dengue, and, more recently, AIDS and Ebola. However, recent studies have expanded our understanding of other consequential effects that viruses have on us as humans. Previous studies have emphasized the importance of bacteria to our metabolism, immune system and overall health. This bacterial cooperation between our general cellular selves and our microbial partners has been termed our microbiome. Now, there is emerging data about a coexistent virome. This is the collection of viruses that play an intrinsic part in our vast microbial partnership and enables us to survive as complex organisms.
New information is revealing that certain viruses are essential for our well-being. For instance, the commons murine norovirus has been demonstrated to help repair inflamed intestinal tissue in mice. It helps restore immune defenses when the microbial component of our immune systems is damaged by antibiotic therapy. In research studies, mice that have their microbiome artificially depleted are protected from damage if pre-treated with murine norovirus.
The symbiotic contribution of commercial bacteria is well known. What has remained obscured until now is the essential contribution that eukaryotic viruses have on our homeostatic mechanisms. This refers to the complex biochemical and immunological checks and balances that all complex organisms display. A recent study confirms and further defines these deep interlocking relationships. The presence of murine norovirus among gut flora restores intestinal morphology and lymphocyte function. Research has confirmed that these effects are profound. Investigators found that those effects included transcriptional changes in the intestinal mucsoa associated with immune development and potent effects on interferon, an essential mediator of our immune system. These studies demonstrate that the presence of murine norovirus can compensate for the loss of necessary bacterial companions. What experiments such as these are proving is that viruses are also part of our enlarged hologenome and essential for the balance of cellular forces that keep us healthy. Viruses are not just pathogens. Some of them are necessary to support intestinal homeostasis and are critical in shaping intestinal mucosal immunologic status. This range of action is similar to that of the microbiome that has itself only recently been explored in depth.
What might we make of these findings? The answer lies within re-envisioning ourselves as much more than unitary beings. We are vast interlocking collectives of life seamlessly constructed as to seem one. We are hologenomes.