In Hershey and Chase experiment, they worked with viruses that infect bacteria called bacteriophages.

The steps involved in their experiment :

Infection - Radioactive phages were allowed to attach to E. coli bacteria

Blending - The viral coats were removed from the bacteria by agitating them in a blender. 

Centrifugation - The virus particles were separated from the bacteria by spinning them in a centrifuge.