Factors affecting the interferon sensitivity of human cytomegalovirus

Several factors affected the interferon sensitivity of human cytomegalovirus in human foreskin fibroblast cultures. An inoculum of infected cells was up to 300-fold less sensitive than a cell-free inoculum of equivalent input multiplicity. A 10-fold increase in the dose of infectious units of either type of inoculum was associated with a 10-fold or greater decrease in interferon sensitivity. Several aspects of the virus-cell interaction were examined and parameters indicative of cell infection were less inhibited by interferon than were those for virus replication.