Dodatak:Popis virusa, O
Ok uredi
Okavirus uredi
Ol uredi
, Oleavirus:
Om uredi
, Omegapapillomavirus: , Omegatetravirus: , Omikronpapillomavirus:
Op uredi
, Ophioviridae , Ophiovirus:
Or uredi
, Orbivirus: , Orthobunyavirus: , Orthohepadnavirus: , Orthomyxoviridae , Orthopoxvirus: , Orthoreovirus: , Oryzavirus:
Os uredi
, Oscivirus: , Ostreavirus:
Ou uredi
, Ourmiavirus: