IMO viral infections can be enablers/triggers or opportunistic bystanders adding to the damage, doesn't mean you shouldn't treat them if necessary. But the countless inconclusive serum studies suggest that a virus is unlikely as a chronic agent at this point. I don't have a problem if they eventually come around and announce a virus like EBV or coxsackie as the culprit, but I have the gut-feeling that this will not happen. Simply considering how much effort has been spent chasing viruses/parasites etc. and how little effort has been spent looking for misplaced opportunistic bacteria, it would make sense to do some research there. But again, this can only happen with tissue samples and biopsies which are notoriously hard to get due their invasive nature, cost, and legal reasons.