if you go to amt's website (amt is the licensee of amgen's gdnf), there is a fascinating video about viral vectors...very encouraging. AMT is a relatively young company (1998) but this is quite impressive, and hopeful. Of course, they have the benefit of knowing already that gdnf works, the only trick is how to get it to where it's needed...I think this is the link to the video:

http://www.amtbiopharma.com/mod.php?...age&page_id=74