It's an interesting story but it looks pretty speculative to me. Certainly the link to ME is entirely speculative.
When you say it looks speculative, do you mean the idea that terminally deleted viruses are playing a causal role in myocarditis and ME/CFS is speculative? Or that it is speculative that these terminally deleted viruses are present in myocarditis and ME/CFS?
Certainly it would be nice if we could have more investigation into terminally deleted enteroviruses, to establish their degree of involvement (if any) in various enterovirus-associated diseases, such as CVB myocarditis, ME/CFS and type 1 diabetes.
There is evidence for terminally deleted enterovirus involvement in ME/CFS: Dr John Chia in his
2008 study (full paper
here) showed that normal lytic enteroviruses are not always found in ME/CFS patients, in spite of the fact that enteroviral RNA can be detected. So this state of affairs, like the CVB myocarditis case, suggests there is an infection with terminally deleted enteroviruses, and that this might be playing a causal role.
Also,
Cunningham et al in 1990 (full paper
here) found that in the enteroviral RNA isolated from the tissues in ME/CFS patients, there was much more negative stand RNA than is normally found in normal lytic enterovirus infections. Normally in lytic enterovirus infections, you find a 100 times more positive strand RNA than negative strand RNA.
But Cunningham et al found that in ME/CFS patients, there was roughly
equal amounts of positive and negative strand enteroviral RNA; this is characteristic of non-cytolytic, terminally deleted enterovirus infections.
After an acute enterovirus infection has been cleared up by the immune system, and no more viral particles can be found, an intracellular non-cytolytic enterovirus infection may remain, and this ongoing chronic non-cytolytic infection may turn out to provide an explanation of why we observe continued chronic immune attack / inflammation (even if it is not true autoimmunity) in organs or cells hit by an acute enterovirus infection.