/opt/sophos-av folder disappeared in Ubuntu server

Hello, I had installed a copy of the sophos antivirus before it became a payed product: I then kept using the savscan utility for casual scanning, with the outdated virus database, until the other day, when I launched savscan only to find that there was no more savscan command available. I found out that all the folder /opt/sophos-av was missing, and I did not delete it: I'm the only one with root access to the machine. I haven't found any trace or symptom of intrusion, by looking at logs and running a coupe of rootkit hunters. Moreover, the folder disappeared in a timeframe of some hours because it's available in a backup.

Is it possible that the installation has been deleted itself? Any suggestions? Thank you