In vitro inhibition of Herpesvirus sylvilagus by phosphonoacetic acid and phosphonoformate

Antiviral effects of phosphonoformate (PFA, foscarnet sodium)

This article describes the antiviral properties of foscarnet (trisodium phosphonoformate) at the enzyme level as well as in cell cultures and in vivo. The mechanism of action against herpesvirus DNA polymerases and reverse transcriptases is outlined. Clinical studies using topical foscarnet against mucocutaneous herpes simplex virus infections are presented. The clinical use of intravenous foscarnet against severe viral infections caused by cytomegalovirus, hepatitis B virus and human immunodeficiency virus is discussed.

In vitro antiviral effect of 9-(2-hydroxyethoxymethyl) guanine on the fish herpesvirus, Oncorhynchus masou virus (OMV)

The antiviral activity of 9-(2-hydroxyethoxymethyl) guanine (Acyclovir, ACV) on the salmon herpesvirus, Oncorhynchus masou virus (OMV), was studied in vitro. ACV showed high efficacy against the fish herpesvirus OMV, Herpesvirus salmonis and channel catfish virus (CCV). Cytopathic effect (CPE) induced by 100 TCID50/ml of OMV in rainbow trout gonad (RTG-2) cells was inhibited by 2.5 micrograms/ml of ACV. ACV was more effective than other compounds such as 9-beta-D-arabinofuranosyladenine (Ara-A), 5-iodo-2'-deoxyuridine (IUdR) and phosphonoacetate (PA). Growth of RTG-2 cells was considerably inhibited by ACV at 25 microgram/ml, but no morphological changes were observed in the cells. Replication of OMV in RTG-2 cells inoculated with 100 TCID50/ml was completely suppressed by 2.5 microgram/ml of ACV. Addition of ACV within 4 days post infection was effective in reducing OMV replication. In order to be effective, ACV had to be present continuously.

In vitro and in vivo inhibition of myxoma virus by treatment with phosphonoacetic acid

Both myxoma and fibroma viruses were found to be sensitive in vitro to the effects of phosphonoacetic acid. Detectable myxoma virus replication was inhibited at a drug concentration of 100 micrograms/ml. Fibroma virus replication was inhibited at a concentration of 500 micrograms/ml. Because of this difference in sensitivity, myxoma virus was used to infect rabbits to test that efficacy of phosphonoacetic acid in the treatment of a systemic viral disease. Rabbits were given 400 mg kg-1 day-1 of phosphonoacetic acid subcutaneously in two injections. Phosphonoacetic acid-treated animals showed a reduction in the severity of disease. Neither serum viral antigen nor infectious virus could be detected. In phosphate buffered saline-treated animals both serum viral antigen and infectious virus were found. All animals treated with phosphate buffered saline died of myxomatosis.