In-Silico Drug Discovery of Dengue Virus Protease Inhibitors

An estimated 2.5 billion people live in regions at high risk for Dengue virus (DENV) related epidemic transmission and up to 100 million people are infected annually.  Long-term goal of this project is to provide a therapeutic alternative that can be used for effective treatment of DENV infections.  Working hypothesis to be tested was that: “Selective, high-affinity inhibitors of Dengue virus replication can be identified via an In Silico approach targeting NS2B/NS3 viral protease complex formation”.  In order to test this hypothesis we followed our novel drug discovery strategy including: (1) Creation of pharmacophore models based on information obtained from In Silicodocking of small chemical probes; (2) Prescreening of a lead-like drug database (>1.7 Million small chemical compounds) against these pharmacophore models; (3) Docking of drugs selected by the models, against a well-defined protein target in NS3.  Top-hits were ranked by predicted “binding energies” (kcal/mol), with a total of 418 compounds identified with values below -9.5 kcal/mol (predicted sub-micromolar affinities).  Five of those compounds were randomly selected and tested for cell toxicity and antiviral activity.  Four of the five compounds were found to have significant viral replication inhibition, while three of those compounds demonstrated an average survival of over 85% at a concentration of 100µM.  In conclusion, our initial In Silico campaign resulted in the identification of large number of potentially high affinity top-hits, while results from our limited bioassay is consistent with the possibility that a significant number of those top-hits are biologically active and with low toxicity.