Studies on herpes simplex virus. I. The stability and preservation of egg-adapted herpes simplex virus.

In animal tissues the virus of herpes simplex is very stable and can be preserved at refrigerator temperature or in the frozen state for many months. Egg-adapted herpes virus, on the other hand, is said to be relatively unstable so that it cannot be satisfactorily preserved and stored (Scott, 1948a,b). Two recent standard texts on viruses state that "egg virus appears harder to keep, very little surviving for 6 months even in a dry-ice cabinet" (Scott, 1948a) and "as egg material, however, only 1 out of 7 specimens were recoverable after 7 months in the dry-ice box. This deterioration is apparently not influenced by quick or slow freezing or by any of the three recommended diluents.2 When frozen from the moist state and kept at -20 C the activity of the egg virus should not be relied upon for more than 7-10 days" (Scott 1948b). These statements might imply that the physical, chemical, or even biological properties of herpes virus in egg material differ greatly from those of the virus in animal tissues. As an alternative the possibility must be considered that the chemical and physical properties of the menstruum greatly influence the stability of the virus. In this respect the complexity of animal tissues might well have advantages over simpler suspending media. In this report it is shown that certain suspending media permit the adequate storage of egg-adapted herpes simplex virus for many months. Quantitative data are given indicating the relative efficiency of several menstrua in the preservation of such virus at low temperatures. In addition, storage in the dry-ice cabinet (-70 C) is compared with storage in the electrically operated mechanical refrigerator (-20 C).