I am not sure you understand the term isolation in relation to so called virology. From the Merriam-Webster dictionary: “to isolate is to separate from another substance so as to obtain pure or in a free state”. So they have to collect samples of bodily fluids from supposedly infected persons, then using various techniques separate the viral particle from all other cellular waste in the samples. Then when it becomes the only thing left in the sample in its purest form, it needs to be properly characterised. And finally it has to be scientifically proven to be contagious which must include conducting proper control experiments.

The last paper you sent does nothing of the sorts. It just takes some supposed viral samples (who knows how they were originally obtained) from 3 different sources and basically just injects them straight to mice brain. Which personally I think is completely pointless animal cruelty. What is interesting, the authors themselves write that they could not make any mice sick by natural means of propagation, only with brain injections. Duh 🤦‍♂️