What is the current regulator perspective on antivirus for Linux/UNIX?

As a compliance analyst, I’m trying to determine whether current regulators are requiring antivirus on Linux/UNIX platforms? PCI-DSS states it must be deployed on all systems commonly affected by malicious software…I don’t believe Linux is to the point where it’s commonly affected. What about other regulations? I’ve also read that antivirus would be a good idea on the non-windows platforms in order to prevent transmission of windows viruses.
Thanks for the help.