Seeing as how there aren't any that makes very little sense to go looking for them.
It is bit like looking for elepants at the north poles. You can do it but why?
What makes you think that it might be infected?
Have you been visiting questionable sites?
Downloading software from untrustworthy sites?
There are no viruses in the open for Macs, but there is malware that can be a mess to deal with. See the site http://www.thesafemac.com for further information.
Avoid commercial anti-virus software like Norton and McAfee as they are particularly bad for Macs.