I think the best virus protection is common sense.

Even on my windows machines, I don't use it unless I have abnormal behaviour.
I've only been virused twice since I started using computers in '83.
One was virused by the system builder, we tracked it down to the mouse
disk. The other time was my fault, but I was on major pain killers in
the hospital at the time. I got curious and opened one of those
attachments.

With linux, it's so rare that you can for all practical purposes ignore it.