Anesthetic action and virus replication: inhibition of measles virus replication in cells exposed to halothane.

Replication of measles virus in BSC cells was studied in the presence of halothane, a commonly used volatile anesthetic. At clinical concentrations of the anesthetic, appearance of progeny virus was decreased in a dose-related manner. This inhibition was reversible as the removal of halothane allowed virus replication to be resumed. Studies attempting to elucidate the mechanism of action of the anesthetic inhibition of virus replication revealed that halothane did not directly inactivate the virus particle or prevent viral adsorption to the cell. Infectious virus and nucleocapsid production were decreased or stopped, depending on the anesthetic dosage used. Direct immunofluorescent staining for measles virus antigen was negative in cells treated at the higher concentrations of halothane. Recovery of nucleocapsid production started within a few hours after removal of halothane. Furthermore, the combined inhibitory effects on viral ribonucleic acid synthesis of 5-azacytidine and halothane were additive. This evidence suggests that inhibition of measles virus replication occurs at or before ribonucleic acid synthesis.