Virtual Screening and Biological Validation of Novel Influenza Virus PA Endonuclease Inhibitors

The Influenza Virus RNA-dependent RNA polymerase complex (RdRp), a heterotrimeric protein complex responsible for viral RNA transcription and replication, represents a primary target for Antiviral drug development. One particularly attractive approach is interference with the endonucleolytic "cap-snatching" reaction by the RdRp subunit PA, more precisely by inhibiting its metal-dependent catalytic activity which resides in the N-terminal part of PA (PA-Nter). Almost all PA inhibitors (PAIs) thus far discovered bear pharmacophoric fragments with chelating motifs able to bind the bivalent metal ions in the catalytic core of PA-Nter. More recently, the availability of crystallographic structures of PA-Nter has enabled rational design of original PAIs with improved binding properties and Antiviral potency. We here present a coupled pharmacophore/docking virtual screening approach that allowed us to identify PAIs with interesting inhibitory activity in a PA-Nter enzymatic assay. Moreover, Antiviral activity in the low micromolar range was observed in cell-based Influenza Virus assays.

Influenza virus PA endonuclease; PA inhibitors (PAIs); dihydroxy-1H-indole-2-carboxamides; metal chelation; pharmacophore−structure virtual screening; polymerase.