We know that a very large proportion of bacteria are essential to our good health. Every other day we see press release about the microbiome, and its multitude of health implications. Is there something equivalent with viruses. Do we have a stealthy microvirome that is essential to our health?
We know a few things about viruses:
Typically, the more successful ones are more contagious but also less lethal. A virus that is more lethal and kills its human host more readily essentially commits suicide by depleting its resources quickly (human host).
Viruses kill a lot of bacteria.
Viruses fight each other off, crowd each other out.
From the above, we can advance an hypothesis of what a smart virus would do:
a) It would be highly contagious, but be rather benign;
b) It would kill "bad" bacteria and not "good" ones;
c) It would crowd out all other viruses to colonize the human host most successfully.
In other words, this smart virus would attempt to keep its human host as healthy as possible and keeping it free from all other bacterial and viral infections and diseases. Meanwhile, it would attempt to keep its human host as healthy and vibrant as possible. So, this human would remain mobile, interact closely with others, so the virus could propagate itself as successfully as possible.
I intuit they are many examples of such smart viruses. The common cold and the flu both come to mind. The common cold being the smarter of the two for obvious reasons (flu certainly reduces your energy and mobility a lot more relative to the common cold).
If the above has a grain of coherence, it would suggest that some benign viral infections and diseases such as the common cold may be actually good for us, as they actually protect us from a bunch of far worse bacterial and viral infections and diseases.
Similarly, do we have zillions of viruses within our bodies that are actually very good for us? They would not need to cause a disease at all, they would live in perfect harmony with their human host. Maybe they would be essential to a human host survival. In essence, do we have a bunch of good viruses within our system just as we have a bunch of good bacteria?