Mode of action in vitro against mengovirus of substituted 5-amino-4-cyanopyrazoles.

Substituted amino pyrazoles were found to exhibit plaque reduction and inhibition of the cytopathic effect of mengovirus on FL cells. Their antiviral activity was not caused by a virucidal effect or by inhibition of viral adsoprtion or penetration but by suppression of the virus multiplication. During a one-step growth cycle maximum suppression of virus yield occurred after compound addition from 0 to 2 h after infection. Progressively less viral inhibition appeared when compound was applied during the later part of virus replication. The antiviral effect was reversible by removal of the compound, and no inhibitor-resistant period occurred.