An important observation concerning the development of the in vitro cytopathic effect is that it can also be inhibited by substances that accumulate in the media of infrequently fed cultures. These substances can be removed by frequently replacing the tissue culture medium. They have been partially purified and characterized, especially since they hold promise in the potential therapy of stealth viral infection. The name "Epione" was coined for the stealth virus inhibitor(s). Epione, is the wife of Ascepius, the Greek God of medicine and mother of Hygenica and Panacea. She was known for her skills in soothing pain, a laudable goal for therapy of stealth virus infected patients.