A virus requires a host cell, so one cannot propagate it in medium. One has to grow the host cell and infect the host cell with the virus. Then one can isolate the virus from the host cell (or medium depending on whether it is a lytic virus or not).
Thank you Dr. Gerad Tromp . I am aware of that sir , That is what we do in plaque assay to isolate viruses against bacteria. But in case of fungi what methodology has to be adopted ? Fungal cells are entirely different so how can one propagate the virus . i am so curious to know the procedure for the isolation and propagation