My lab experience is far removed, involving soil bacteria, archaea and fungi, the isolation of which can be done with feedstock, toxins and centrifuges. It is interesting that 'we' were not able to differentiate archaea from bacteria prior to genetic analysis. [not via microscopy]yes, we do have a different definition of "isolation" - you are using the virologist definition. however when they say " using Vero CCL-81 cells by observing cytopathic effects (CPEs) ", that is not a separation of the virion from everything else, what i would call isolation - Vero cells are monkey kidney cells. and cytopathic effects refers to shooting the monkey cells with antibiotics and starving the cells so it breaks down. all this makes my engineering-mind go into critical questioning mode. i don't have the lab experience to really get the details, so i read studies from those that do.
have they characterized/isolated/sequenced all the cellular debris they are bringing into the test? the answer is no, since everyone does it this way.
have they done a control study, where they run all the same procedure but without putting the virion into the stew? the answer is no, cause nobody does that. except one guy that got all the same results but using yeast cells instead of virion.