Downadup is a worm even if you clean one PC & fi the other PC are infected it come back . you need to Make sure you have these thing in place you wont get the virus back.
1.Make sure that all the Microsoft security patch & KB958644 is installed on all the machines.
2.Install the latest rapid release signatures on all the machines.
3.Disable Autoplay from all the machines for all the drives.
Click Edit to start Group Policy Editor. In the Computer Configuration section of the GPO, expand the Administrative Templates folder.
Click System, and then in the right pane, double-click the Disable Autoplay policy object.
Click Enabled, and then confirm that the All drives object is selected.
Click OK, quit Group Policy Editor, click the Properties dialog box, and then quit the Active Directory Users and Computers snap-in
4.Enable network scanning on SEP from the Manager.
5.Close the default shares.(Admin$, C$ and other open shares).
6.Start scanning on all the machines.