Development of Flavivirus Antivirals Targeting Dengue Virus and WNV Protease

DESCRIPTION provided by applicant Mosquito borne members of the Flavivirus family include four serotypes of dengue virus DENV and West Nile Virus WNV and are classified as re emerging pathogens due to the frequency and severity of recent epidemics There are an estimated million DENV infections reported each year resulting in nearly deaths More than billion people are at risk of infection by DENV Symptoms of dengue fever include fever rash and arthralgia In more severe cases viral infections can develop into life threatening dengue hemorrhagic fever or dengue shock syndrome Dengue shock syndrome occurs when leakage and or bleeding is sufficient to induce shock which often leads to death especially in children due to the lack of adequate supportive care WNV infections can result in meningitis encephalitis or paralysis leading to mortality among hospitalized patients Year witnessed a sudden surge in the number of WNV infections comprising andgt cases in states with deaths Despite the high morbidity and mortality resulting from flavivirus infections in a subset of patients there is currently no effective chemotherapeutic treatment for infections for any of the flaviviruses The combined global socioeconomic impact of flavivirus pathogens merits an urgent need for new and effective antiviral therapeutics The Flavivirus RNA genome encodes for three structural proteins C prM and E and seven nonstructural proteins NS NS A NS B NS NS A NS B and NS The NS protein is a multifunctional enzyme that contains protease helicase and RNA triphosphatase activities The N terminal region of NS has a serine protease domain which in the presence of the NS B cofactor NS B is an active serine protease This protease NS B NS pro plays an essential role in the cleavage of the viral precursor polyprotein and disruption of this function is lethal t viral replication Therefore blocking viral replication by inhibiting the quintessential viral protease could lead to the development of effective broad spectrum antiviral therapeutics and is the focus of our research proposal The innovation of our proposal is the discovery of two lead inhibitors which have broad spectrum DENV and WNV inhibitory activity and contain a catechol moiety which is also a substructure present in FDA approved drugs In addition the modeling data suggest the compounds bind to the enzyme substrate binding pocket and thus act as competitive inhibitors Therefore these properties of our leads support the feasibility for development into effective broad spectrum antiviral therapeutics The specific aims for Phase I of the proposal are Design and synthesize broad acting inhibitors of DENV and WNV NS pro Milestone Compounds with IC d nM against DENV and WNV protease will be advanced into cell based assays Evaluate the therapeutic indices of optimized lead compounds using in vitro cell based replicon infectivity EC and cytotoxicity CC assays Milestone Identify lead compounds with EC d nM and CC e uM representing the catechol and non catechol series Conduct in vitro ADME based lead optimization of compounds with broad spectrum in vitro activity and acceptable therapeutic indices Milestone Identify lead compounds exhibiting high bioavailability weak inhibitor of CYPP s optimum stability and are not hERG channel blockers for evaluation in in vivo animal models for acute toxicity efficacy and pharmacokinetics Phase II application PUBLIC HEALTH RELEVANCE Emerging human pathogens such as dengue virus serotypes DENV yellow fever virus YFV West Nile virus WNV and Japanese encephalitis virus JEV are in the NIAID list of Category A B or C priority agents which belong to the Flavivirus family Despite the morbidity and mortality caused by flavivirus infections there is currently no effective chemotherapeutic treatment for infections by any member of the Flavivirus family The combined global socioeconomic impact of the flavivirus pathogens merits an urgent need for development of effective antiviral therapeutics Given the overall similarity in the genomic organization and the known D structures of the DENV and WNV proteases suggest that blocking the viral replication by inhibiting the viral serine protease is a promising approach for anti flaviviral drug development and is the focus of this proposal