There's a version of Sophos available for Linux systems. Can't express any opinions on it, and no idea what the price may be (we got it free as Uni members), but it's there.

FWIW, I use ClamAV, as that's available in both Debian and Ubuntu distributions' standard lists, for free; that, and serious (automated and manual) web-browser paranoia, serve my humble purposes. But I'm open to suggestions (and brickbats).

Quick, Jeeves! my asbestos mail-reading long-johns!