I'll let the McAfee Labs people answer you but I would imagine that as this is a game of catch-up with new variants of these things appearing constantly there will always be things that escape antiviruses of any brand.
They rely on submissions a lot to cover unknowns and there are various tools for that and to help rid your machine of pests in the last link in my signature. GetSusp and Stinger for instance.
There is a white paper on this infection published by McAfee here: http://www.mcafee.com/us/resources/reports/rp-operation-high-roller.pdf
You'll need Adobe Reader or Acrobat to read it.
Hopefully they will add to this thread soon.