The Norwegian woman, infected by the Ebola in Sierra Leone and currently receiving treatment in Oslo, will get the last dose of the virus treatment medicine ZMapp
…and yet again, the emphasis is on how slow it is to make it – when the whole point of biofarming and transient expression is that it is supposed to be QUICK to make things, and easy to scale up production!!
What is the problem here? KBP has facilities – or says it does – for large-scale production of proteins via transient expression in N benthamiana via rTMV or even BeYDV-based vectors. SO why has it been so difficult to make more ZMapp??
Why, in fact, are we told via other reports that the US government is considering getting Caliber to make it, or even to make the cocktail in CHO cells, because of capacity, when KBP has the equipment?
It can’t be supply of plants, surely: if they’d planted out a big greenhouse or two of N benth the moment ZMapp hit the news, they’d have enough to make many grams of ZMapp right now – given that it takes just a few days of incubation post-infiltraiton to make the protein.
Surely it’s not a protein purification thing – because THAT’S pretty quick too, once the plants have been mushed.
So what IS the bottleneck? cGMP requirement? Lack of certified protocols / equipment? Can someone tell us?? Otherwise, a posterchild for biofarming will end up being made by good old stainless steel cell culture technology, and our favourite way of doing things will have been found to be wanting.
NOTE ADDED 10th October:
Never let it be said I was unwilling to get schooled by a former colleague…Kenneth Palmer just told me what the problem is:
“You may not be aware that the human dose of Zmapp is 12 grams per patient, 3 infusions of 4 grams each. Check the dose in recent Nature paper. If yield of one antibody is 100 mg per kg and you have to produce three antibodies for Zmapp… If you do the arithmetic you will see why the process is “slow””.
So…. Doing just that, you end up with 30 kg N benthamiana per gm of ZMapp as a best-case yield – meaning 360 kg PER PATIENT.
That’s a LOT of N benth – and tooling up for that sort of plant production takes time. Thanks, Kenneth!
I would be VERY interested in a cost breakdown of ZMapp vs CHO cell-produced MAbs – because producing at that sort of scale MUST be prohibitively expensive in stainless steel?