Not at this time. See:
Helpful Links Regarding Malware Protection
An excellent link to read is Tom Reed's Mac Malware Guide.
Also, visit The XLab FAQs and read Detecting and avoiding malware and spyware.
See these Apple articles:
If you require anti-virus protection I recommend using ClamXav.
No..... do not installed any anti-virus for mac,will not perform well at all particular mac keeper stay this away,all macs have their own defence for protection from malwares unlike windows must installed protection ....if you are on mountain lion then have even much stronger defence this call gatekeeper...so you dont need any protection at all
If you manage file coming and going to Win PC's your Mac might not detect PCs viruses but for your costumer's health would be nice to kill viruses in incoming files (in order to don't have them in outgoing files). It depends on what you're doing and what you wanto to do.
Personally I do have ClamXav and I run it once a while.