here is a viral experiment: take a sample from somebody who is unwell. grow vero cells at 10% fetal bovine serum (FBS). ensure the cells are virus free because you got them from a certified supplier. reduce the FBS to 2% for maintenance. then inject the viral sample. Then wait and observe the cytopathic effects of cell death. then sample the dish to look for foreign genomic material that you call virus.

1. the cytopathic effects might be from the maintenance concentration

2. the cytopathic effects might be from the virus

3. of course you will find foreign dna because you introduced it to the medium.

this is a modern viral experiment and it unfortunately can't show anything except that you can get foreign DNA from a sample that you introduced foreign dna into in the first place.