Virus classification http://www.ictvonline.org a virus species is a polythetic class of viruses that constitute a replicating lineage and occupy a particular ecological niche Apolythetic class is one whose members have several properties in common, although they do not necessarily all share a single common defining property. In other words, the members of a virus species are defined collectively by a consensus group of propertiesVirus Classification http://www.ictvonline.org/ “a virus species is a polythetic class of viruses that constitute a replicating lineage and occupy a particular ecological niche”. A “polythetic class” is one whose members have several properti i l h h h d il ll ies in common, a l thoug h they do not necessarily all share a single common defining property. In other words, th b f i i d fi d ll ti l b the mem bers o f a virus spec ies are d efine d collective ly by a consensus group of properties