Variation of herpes simplex virus in persistently infected tissue cultures.

Hinze, Harry C. (University of Wisconsin, Madison), and Duard L. Walker. Variation of herpes simplex virus in persistently infected tissue cultures. J. Bacteriol. 82:498-504. 1961.-Cultures of human conjunctiva, HeLa, and KB cells infected with herpes simplex virus (HF strain) were cultured for prolonged periods in medium containing low levels of antibody. After continuous culture of the infected cell lines for 6 months, two major changes were noted in the character of the virus present in the cultures. These changes consisted of an alteration in the type of cytopathic effect produced by the virus and marked loss of virulence for mice. Further study of the virus from the cultures revealed that it was still antigenically similar to the original strain of herpes virus. It was found that the variant produced an altered, proliferative type of cytopathic effect only in the presence of herpes antibody. The variant multiplied more slowly in human conjunctiva cells in culture than did the parent virus, and the variant had lost practically all capacity for multiplication in the brain of mice.