W97M/Ded is Word 97 class infector. Some variants of it are polymorphic. When an infected document is closed, W97M/Ded.A infects the global template and all closed documents thereafter.
The virus saves the the active document after it has been infected. While this action is visible in Word's status bar, the file is not added to the list of the recently accessed files list to the "File" menu.
W97M/Ded.A is polymorphic. It adds random comments to the code and splits code lines from a random position.
Disinfection & Removal
W97M/Ded.B is a non-polymorphic variant of W97M/Ded. When an infected document is closed, it infectes the global template.
The virus attempts to infect an active document when it is closed.
W97M/Ded.D is functionally similar to W97M/Ded.B.
Technical Details: Katrin Tocheva and Sami Rautiainen, F-Secure