@The Mighty Monkey of Mim The Klingon and Human brains are not a unknown quantity; Kobliad brains kind of were.
Also, why would there be a different version of the Augment Virus in play? That doesn't make any sense.
If the Klingon scientists created the one virus we know about, it's certainly possible they created other strains we didn't hear about until now. Either at the same time, or later than the 2150's.