From what I read, it's simply an oligomerizer - a composition of 3 major proteins structures : identifier (identify virus related dsRNA > 30~50) + activator (trigger the cell suicide with precaspase) + deliverer (allow DRACO entering living cell), in essence a chimeric protein. It's probably introducing these 3 domains of combined DNA into certain engineered bacteria and incubated, then purified the chimeric protein the bacteria produced. In standardized manufacturing, I think it will be cheap. (Some medicines already using similar manufacturing methods). I am not sure how they were sure the combined protein structure remained folding with the right shape and functions, but I guess they just try it anyway, or the details are just not included.
Customized is done via different domains. It's already mark at least 5 different Identifiers for identifying different dsRNA. (the identifier using in mice is PKR). And 3 different kind of activators to trigger cell suicide. And the deliverer is just added to allow the DRACO entering the cell, but it also has 3 kinds. (It compares the effectiveness of these 3 kinds of deliveries combined with one kind of identifier - PKR. Two of the deliverer proteins are even from HIV, since it's so successful in masking its way into human cell.). So it's not customized to particular person, but rather combined all the bests in these 3 domains and create a series of different DRACOs.
And I don't think the sequences itself (and the proteins) can be patents, but the manufacturing processes can.