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The antiviral activity of acycloguanosine 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. [ABSTRACT FROM PUBLISHER]

Comparisons of the anti-herpes virus activity of idoxuridine, cytarabine, vidarabine, trifluorothymidine and ara-DAP were made in vitro and in vivo. Although the activity of these compounds was substantiated in vivo, the test methods were insufficiently sensitive for adequate comparisons of relative activities to be made. It was found that such comparisons are best made in vitro by the plaque reduction technique, by which cytarabine was found to be the most active compound on a molar basis available at the present time. [ABSTRACT FROM PUBLISHER]

The anti-influenzal activity of ribavirin and amantadine hydrochloride has been compared in different test systems. Strains belonging to the four A sub-types H0N1, H1N1, H2N2 and H3N2 were employed. Although some variation was found between systems, the four strains were found to be of similar sensitivity to ribavirin, the inhibitory activity of which differed very little from that of amantadine hydrochloride with the more recent strains. In mice the sensitivity of the strains to the two compounds appeared to decrease with increasing passage in the mouse lung up to the 30th passage level. It is suggested that ribavirin should be used as a tool to check that viruses are similarly adapted to mice, particularly for strains which are not very sensitive to amantadine hydrochloride. [ABSTRACT FROM PUBLISHER]

Acycloguanosine, a recently developed compound with high inhibitory activity against viruses belonging to the herpes group, has been evaluated in experimental herpes simplex keratitis in rabbits in comparison with trifluorothymidine and preparations of idoxuridine and vidarabine at present in clinical use. All compunds were used in the form of ophthalmic ointments which were applied 5 times a day at intervals of 2 hours. Treatment began on the third day of infection and was continued for 4 days. Complete cure was obtained with acycloguanosine and idoxurdine; trifluorothymidine and vidarabine were considerably less effective. Acycloguanosine was equally effective when given intravenously in the form of its sodium salt, and could be detected in the tear fluid in inhibitory concentrations when given by mouth. The compound was relatively free from toxicity. [ABSTRACT FROM PUBLISHER]