Methisoprinol-effect on the replication cycle of human hepatitis A virus

The antiviral activity of methisoprinol was investigated under different conditions using a strain of hepatitis A virus (HAV), that shows a strong cytopathic effect on the Frp/3 cell line 7-9 days post-infection. Treatment of Frp/3 at a dose range of 125-1200 micrograms/ml had no toxic effect and showed a dose dependent inhibition of the HAV replication cycle. At the methisoprinol dose of 500 micrograms/ml the cytopathic effect was completely abolished and HAV antigen production reduced by 50% as measured by indirect immunofluorescence (IIF) and commercial enzyme-linked assay (ELISA). The virus yield was virtually abolished at the highest dose employed (1000 micrograms/ml).