They do know the vector, but from what I have read there is no cure.
You may be interested in reading Ann Peck's e-book. It was written in 2007 and she has done further studies and work on rose rosette since then, but I still think her e-book is a very good starting point in learning both about RRD and about the misleading research that had been published.
http://www.rosegeeks.com/
From what I have read, many of the new studies haven't added anything new to what is known about RRD and is already mentioned in Ann's book.
It's worth a look.
