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FINDER: FIghtiNg DEngue viRus, a novel strategy for the development of fully protective antivirals that act by disrupting the DENV NS3/NS5 interaction

Periodic Reporting for period 1 - FINDER (FINDER: FIghtiNg DEngue viRus, a novel strategy for the development of fully protective antiviralsthat act by disrupting the DENV NS3/NS5 interaction)

Okres sprawozdawczy: 2018-05-01 do 2020-04-30

Dengue virus (DENV) is a virus transmitted by mosquitos that has spread to more than 130 countries in tropical and subtropical regions of the world. All four serologically different DENV are responsible for around 390 million infections, annually. While the majority of DENV infections cause a mild acute febrile illness called dengue, approximately 500,000 cases every year develop a severe dengue with potentially deadly consequences. Nearly half of the global population is currently exposed to the virus and due to global, environmental and economic factors (e.g. rising temperatures, increasing urbanization, and intercontinental travels), the frequency and the global distribution of DENV infections are expected to further grow in the future. Although DENV represents a major threat to global public health, no specific treatments or a fully protective and safe vaccine are available to treat and prevent DENV infections, highlighting the urgent need for developing new antiviral agents able to tackle this virus.
The identification of molecules able to block specific and critical viral targets would clearly have an enormous impact on society. Indeed, antiviral drugs would dramatically decrease the global disease burden of dengue by essentially preventing the deadly complications and reducing the mortality rate of DENV infections. As a consequence, the availability of effective therapeutic options for DENV would also have a profound economic benefit as it will help to reduce the huge economic losses due to the costs incurred for hospitalisation and supportive care, mostly in low/middle-income countries.
This project is focused on the early stages of the drug development and the main objective of FINDER is the development of innovative and effective anti-DENV therapeutic options able to disrupt the interaction between the viral NS3 and NS5 proteins, which play a key role in the viral replication. Since this target is highly conserved among the different DENV serotypes, the inhibition of this interaction by small molecules may represent a promising strategy for the development of drugs with efficacy against all DENV. Moreover, this class of compounds could be less prone to induce resistance as increasing evidence suggests that dissociative inhibitors of protein-protein interactions possess a high barrier to drug resistance. Overall, this project led to the identification of antiviral compounds acting by disrupting the NS3-NS5 interaction, paving the way for the development of a new class of selective anti-DENV agents.
In the effort to develop selective anti-DENV agents that act by interfering with the NS3-NS5 interaction, the available structural information of DENV NS3 and NS5 was analysed by computational techniques to identify conserved and druggable targets at the interaction interface of both proteins. The two identified targets were used to perform two distinct computer-aided virtual screening methods of millions of small molecules. Computer-aided drug design techniques allowed the rationalisation of the drug design, significantly reducing the duration and cost of early-stage drug discovery compared to the traditional approach. A series of increasingly more accurate computational programs were then applied to select Hit molecules for their potential to specifically interact with the viral targets. From both screening approaches, a number of potential inhibitors of NS3-NS5 interaction were selected, purchased and biologically evaluated. The ability of the selected Hit compounds to specifically interfere with NS3-NS5 interaction was tested in a developed and validated in vitro interaction assay able to measure the binding between these two viral proteins. All the Hit compounds were also tested in cell-based assays to assess their antiviral activity against DENV and cytotoxicity properties. Among the purchased Hit compounds, some molecules were able to specifically disrupt the interaction between NS3 and NS5 in a dose-dependent manner and block the DENV replication at non-cytotoxicity concentrations. The most interesting compounds were further evaluated in secondary cellular tests and subjected to Hit optimisation studies in order to identify structural analogs with more potent and selective activities and possibly endowed with drug-like properties. These studies led to the identification of structural analogs with improved inhibitory effects compared to the respective starting Hit compounds.
The results of this project, avoiding any confidential information, were extensively communicated at the most prestigious international conferences in the field of antiviral drug research and through academic seminars and several outreach activities. Considering the lack of available antiviral agents against DENV, the identification of potential preclinical drug candidates has a clear and attractive commercial potential, and we are currently exploring the possibility of protecting the new intellectual properties (IP) generated during the project. Finally, these results will be published in peer-reviewed, open access journals.
DENV is the most common mosquito-transmitted virus worldwide and poses an increasing global health threat. Since no specific treatment agents are yet licensed for DENV infections, the development of anti-DENV drugs is a priority for global health management. The project is well beyond the state of the art by providing an innovative and successful strategy for developing effective anti-DENV agents based on a novel mechanism of action, the disruption of the viral protein-protein interaction between NS3 and NS5. The research led to the identification of not only novel dissociative NS3-NS5 inhibitors with anti-DENV activity but above all new chemical scaffolds endowed with NS3-NS5 inhibitory activity. These research outputs set the foundation for the development of future therapeutic options for DENV infection that would address the lack of anti-DENV drugs and potentially reduce the global disease burden. Such an achievement would have a huge societal and economic benefit and would generate significant commercial potential and market opportunity.
For this reason, the IP generated throughout this project are expected to be protected and could potentially lead to industrial exploitation. Finally, new techniques (i.e. in vitro and cell-based assays), protocols and data were established and they will continue to be widely disseminated among the scientific community, making useful tools and information available not only for antiviral compound discovery but also for studying DENV biology.
3D structures of NS3 and NS5 proteins