Perhaps it would help us to 'know what non-cytolytic enterovirus is' if you were to point us in the direction of some research papers or other document that explain what it is. I apologise if you have already done so - I'm having trouble keeping up with this thread.
Very happy to, Trish.
As you know, viral particles normally come in spherical shells (called capsids), which break into human cells, then once inside, crack open their shells to release their genetic payload, and these viral genes then start replicating in the cell, in order to construct thousands more viral particles. Those thousands of viral particles made in the cell then eventually break out of the cell, and float off to try to infect more cells. This is normal viral replication.
Some viruses, like the herpesviruses, have a way of entering a cell, and going to sleep, so that they can hide from the immune system inside the cell, undetected for months or years, waiting to return back to life at a later date. That's called latency. Latency is the basis of the chronic presence of a virus in the body. All these viruses like EBV, HHV-6 and cytomegalovirus that are found as a chronic presence in most of the adult population are able to survive long-term in the body because of latency.
You never find a virus like rhinovirus (cold virus) taking up long-term residence in the body, as rhinovirus is not capable of latency, so it cannot hide away from the immune system inside cells, and thus the immune system will completely wipe out any rhinovirus infection, leaving no trace of the virus in the body once the acute infection is over. It's totally eradicated by the immune system.
The typical way a virus maintains a chronic presence in the body is by going into latency (hiding from the immune system). So if a virus is incapable of latency, it may not be able to exist in the body on long-term chronic basis, because the immune system will wipe it out.
Now enteroviruses are not capable of forming latency states, so it is hard to see how you can have a chronic enterovirus infection, ie, a chronic presence of enterovirus in the body.
Thus it was always a puzzle why in conditions such as chronic coxsackievirus B myocarditis, enterovirus was able to produce a chronic infection of the heart muscle lasting years. If enterovirus cannot form latency in order to hide away from the immune system, then you might expect the adaptive immune response to completely wipe out any enterovirus infection of the heart in a matter of days or weeks. But the research showed that enterovirus RNA could be detected in the heart muscle in chronic coxsackievirus B myocarditis even years after the initial acute infection was over.
For decades, that paradox had researchers scratching their heads, until finally, about 20 years ago, it was realized that although coxsackievirus B cannot form latency states, at can form something similar, called a non-cytolytic infection.
A non-cytolytic enterovirus infection is where the naked genetic material of the virus, its RNA, lives inside human cells on a long-term basis, in such a way that the immune system has a hard time trying to kill it. In these non-cytolytic infections, enterovirus no longer lives as the usual spherical viral particle, but rather as strands of naked RNA within cells.
But unlike latency, where the virus usually has gone to sleep, in non-cytolytic enterovirus infections, these strands of RNA are not sleeping, they are actively replicating, albeit at a low-level of activity (ie, they are not prolifically replicating like in the fierce acute infection, but more like a slow, smoldering infection). But even though the non-cytolytic infection is slow and smoldering, the immune system often cannot clear it.
So that is the basis of a non-cytolytic enterovirus infection: it's a smoldering intracellular infection comprising naked strands of RNA that replicate inside our cells. And it is found in ME/CFS.
