PC viruses cannot infect your system, so you're pretty much safe.
You could still get infection from some Amiga software you download online, however I haven't seen infected downloads (say for example Aminet) in years.
Anyway, it's better to be safe than sorry. I suggest using latest VirusZ III, xvs.library, xfdmaster.library and xadmaster.library from
Virus Help Denmark - Amiga antivirus download site.
