If you beg and plead, some of the anti-virus vendors will sell you "Linux anti-virus software". As opposed to anti-virus software that filters Windows viruses that attempt to pass through a Linux system.
While it is possible to write viruses for Linux - and in fact, the first Internet Worm was a Unix program - Linux so far has not been a target for virus authors except indirectly (malware in PDFs and Flash files). Linux is not the most gratifying platform for virus writers. In large part because it runs with tighter security, especially regarding OS-level privileges, in part because there's not as many targets as compared to Windows. And in part because Linux users tend to be more technically savvy, so they're less likely to succumb to most of the social engineering ploys.
So you won't find much in the way of anti-virus software installed for Linux. So far, anyway.
Customer surveys are for companies who didn't pay proper attention to begin with.
The AV-people try to sell you their product, but if you ask them for a signature-file, especially for linux-systems, not for linux as mail~ or fileserver, serving windowsmachines, but for linux as runtime-environment for viruses, you don't get anything.
If you can prove me wrong, I would be very interested in receiving such a file.