The activity in vitro against herpes virus of 9-(2-hydroxyethoxymethyl)guanine (acycloguanosine), a new antiviral agent

Abstract

The antiviral activity of acycloguanosine in vitro was compared with that of idoxuridine, cytarabine, trifluorothymidine, vidarabine and phosphonoacetic acid by means of plaque reduction assays in VERO cells with several strains of type 1 and type 2 herpes virus. The dose-response lines thus obtained showed that acycloguanosine was considerably more active than the other compounds. The activity of all compounds was somewhat lower in HeLa cells. Acycloguanosine was equally effective against type 1 and type 2 herpes, and individual strains varied little in their sensitivity. The other compounds showed wider variations in strain sensitivity, with a tendency for type 2 strains to be less sensitive. Preliminary studies with acycloguanosine showed that its antiviral action took place in the early stages of the multiplication cycle of the virus. Acycloguanosine had very low toxicity to VERO cells. At concentrations at the limit of solubility (20,000 μM), it caused only limited changes in cell morphology and inhibition of cell growth which was reversible. The favourable properties of acycloguanosine indicate that it may be of clinical use in the treatment of herpes virus infections.