Mosnodenvir (JNJ-1802) is an orally active pan serotype dengue virus ( DENV ) inhibitor, with EC 50 values ranging from 0.057 to 11 nM for four dengue virus ( DENV ) serotypes. Mosnodenvir blocks viral replication by inhibiting the formation of complexes between two viral proteins , nonstructural protein 3 (NS3) and NS4B, thereby preventing the formation of new viral RNA. Mosnodenvir exhibits picomolar to nanomolar antiviral activity in vitro and has antiviral efficacy in mice and non-human primates .