Maintenance of human cytomegalovirus genome in human diploid fibroblast cells.

Human embryo lung cells pretreated with a combination of human leukocyte interferon and acyclovir were infected with human cytomegalovirus (HCMV) and treated daily for 14 days with the same inhibitor combination. After removal of the inhibitors, the incubation temperature was maintained at either 37 or 40.5 degrees. Incubation of infected cells at 37 degrees after inhibitor removal resulted in progressive virus-specific cytopathology and eventually total destruction of the cell culture. However, HCMV-infected cells incubated at 40.5 degrees after inhibitor removal exhibited little or no virus-induced cytopathology and HCMV remained noninfectious for 8 days. After extended incubation at 40.5 degrees, infectious HCMV was readily detectable even though virus-specific cytopathology was not evident. Reducing the incubation temperature from 40.5 to 37 degrees resulted in stimulation of infectious virus replication and subsequent destruction of the infected cell culture monolayer within 10 days.