Louis, I am far from a lab guy or scientist or expert on the matter but I can tell you what I know. typically virused seedlings have a very hard time with growth. secondly, most sharry baby come from massed produced clones and are in GH packed with plants. This is great for the spreading of botrytis which I thought was the leaf spotting on many Onc types.
I personally have owned a few plants with the spotting and have grown out the spotting by constant spraying of physan on new growths and cutting old growths. If it was a virus I would assume it would show up on the growths no matter what you did.
I would be shocked to find it's a virus whose effects can be stopped by an antibacterial.