Which DNA mutation of ebola does this vaccination counter?
Ebola is an RNA virus and has no DNA.
This vaccine is against the Zaire strain of Ebola. It should cover the West African variants of the virus as well as the Congo variants used to develop it.
For all we've heard about the mutations, there really are not very many of them, those that exist are within the normal variability of virus that we expect, and the mutations affected the genetic material more than the structure of the virus. So the vaccine, if it performs well in testing, should be effective.