“No virus has been obtained in an absolutely pure state. Not even the washed granules of vaccine virus can be accepted as representing only virus. Therefore it is impossible to say that virus alone is being filtered rather than virus attached to aggregates of protein or particles of degraded cells.”
-Thomas Rivers, Filterable Viruses: A Critical Review
Even after Rivers 1927 admission and as technology progressed, virologists have never obtained a pure sample of any “virus” directly from the fluids. The pictures we see of “viruses” today are of particles created after a cell culture experiment takes place.