Written by: Bonnie Feldman, DDS, MBA, Hailey Motooka, BS and Becca Malizia, BS
So we’ve been talking a lot about bacteria, specifically the millions of bacteria that live in our mouths. We’ve talked about the geographies they live in, communities they form, the good guys, the bad guys, and most importantly how they influence oral health and disease.
But talking only about the bacteria that inhabit our mouths is like only talking about the crust of a pizza. There’s so much more to it!
Now, we want to turn our attention to the other guys– the fungi and viruses–whose presence within the oral microbiome may, like bacteria, have influences beyond the mouth.
Here at Your Autoimmunity Connection, we take a closer examination into the mycobiome (fungi) and virome (viruses) of the oral cavity in our most recent presentation at the Molecular Med TRI-CON conference in San Francisco. In our talk we focus mainly on a type of virus called bacteriophage.
What’s a Bacteriophage?
While the name bacteriophage sounds extremely science-esque, don’t let it intimidate you. They are easily remembered for their unique structure that very much resembles that of a futuristic spider.
Bacteriophages (or just phages) reproduce by essentially infecting and replicating their DNA within a bacterium. They can then hijack the host cell’s reproductive machinery to replicate and multiply. If the surrounding conditions of the host are unfavorable, the phages replicate via the lytic cycle, in which the host cell eventually bursts and new bacteriophages are ‘born’ upon the host cells demise. Yup, pretty scary stuff.
Alternatively, if the surrounding host-cell conditions are favorable, the bacteriophages can reproduce via the lysogenic cycle (yes, that is what you want). The main difference between the two is that the phage does not kill the host cell in the lysogenic life cycle. Instead, the phage attaches to the surface of the bacterium and injects its DNA into the host, eventually integrating itself into the host’s genome.
The whole replication process is reminiscent of The Body Snatchers or Alien, and extremely successful. Within the oral cavity, viruses outnumber bacteria 35:1. Their sub-microscopic size and immense abundance are two reasons why viruses were ignored as having any notable impact on oral health. However, with modern technological advances in -omics research, further understanding of bacteriophages have revealed their increasing importance in biofilm accumulation and, potentially, biofilm management. Oral biofilms are the sticky, white substance that your dentist most likely refers to as plaque. When plaque builds up on the surfaces and within the crevices between teeth, this can eventually lead to oral diseases such as dental caries and periodontal disease.
The Importance of Bacteriophages in the Future of Oral Care
The discovery of antibiotics in the early 20th century revolutionized healthcare dramatically. However, the widespread use of antibiotics to manage and treat bacterial infections has also brought with it the real problem of antibiotic resistance. Scientists are now looking to bacteriophages as a new, and perhaps even more effective method for controlling bacteria and mitigating oral diseases.
Current antibiotic treatments of oral diseases fail to penetrate biofilms and only kill bacteria superficially. Phages, on the other hand, can infect bacterial cells on the outer layer of the biofilm, multiply, and in a chain reaction penetrate into deeper layers of the biofilm. Bacteriophages also exhibit high levels of specificity for the host cells they attach to. Manipulation of this specificity allows for targeting of particular bacterial species, meaning scientists can selectively eliminate certain pathogenic (bad) bacteria in the oral cavity, benefiting both oral health and sparing the deleterious effects of broad-spectrum antibiotics on systemic health.
New understanding of the oral microbiome is shaping how we think about caries, periodontal and oral diseases, as well as diseases far removed from the mouth, such as heart and lung disease, cancer, and some autoimmune diseases. While the traditional view held that mouth diseases were caused by a small number of specific pathogens, we now think of the oral microbiome as an ecosystem of finely tuned bacterial, fungal, and viral communities that all play a role in oral microbiome equilibrium.
View the presentation here