This was posted by Treed last December.
We do not, and for good reason. You should not allow anything to scan Time Machine backups!
Time Machine backups have a special, unique structure that can be very fragile if it is disturbed, and changes should not be made to Time Machine backups by anything other than Time Machine. Allowing a third-party program to alter the backups in any way can destroy the entire backup set. Worse, it can do so without making the problem immediately obvious.
I've seen cases where people have somehow edited these backups outside of Time Machine itself, and the backup continues to work for a while. But then, when it's needed most, it fails and cannot be used to restore data.
For this reason, my advice is as follows:
With any backup system, it's important to have at least two different, redundant backups, created by at least two different backup programs. In my case, that is Time Machine to a Time Capsule plus an external drive, and Carbon Copy Cloner to a couple additional external drives.
Since Time Machine backups can be fragile, never let anything other than Time Machine mess with them. Do not scan them with any antivirus software!
If your machine gets infected and the malware ends up backed up, it can't hurt you unless you restore your machine from Time Machine to a point in time when the machine was infected. Once your machine is clean, all subsequent backups will be clean, and the malware present in older "snapshots" will eventually be flushed from the backup during normal pruning, once the drive becomes full.