First of all note that you don't need antivirus for linux. Check the answer for this question Linux Anti-Virus
For clamav it comes with noGUI but to do it in command line :
To Install Clamav
sudo apt-get install clamav
To update pattern files
To scan all your filesystem and remove infected files
sudo clamscan --infected --remove --recursive /
To download test virus
sudo apt-get remove clamav
But you can use a frontend GUI that works with calmav called AntiVirus Scanner(avscan). you can download from here.
Moreover there are many GUI frontends for calmav. you can check this menu here and choose one of them but i advise you by the one above(avscan)
If you want to use other GUI i advise to use comodo.Comodo has a free, modern, easy to use anti-virus program for various GNU/Linux distributions including Ubuntu 12.04.x.y 32 and 64 bit LTS. The graphical user interface is easy to learn how to use.