Drug-design against the emerging dengue virus – DENGUE D.-D.

In terms of morbidity and mortality, Dengue Fever (DF)1 and Dengue Hemorrhagic Fever/Dengue Shock Syndrome (DHF/DSS) are considered as the most important arthropod-borne viral diseases of humans. It is estimated that at least 50 million individuals are infected annually in the Americas, South-east Asia and Western Pacific resulting in >250,000 DHF cases and at least 21,000 deaths, predominantly of children. Efforts towards the overall control of dengue virus (DENV) infection combine vector control, vaccine development, and antiviral drug-discovery. The four serotypes of DENV (DENV-1 to 4) are members of the genus Flavivirus within the family Flaviviridae, along with a number of other medically important viruses such as West-Nile (WN), yellow fever (YF) and tick-borne and Japanese encephalitis (JE) viruses. In recent years, there has been a gradual geographical expansion of dengue endemic regions. At the French level, DF and DHF/DSS are an important problem in the Caribean, Indian ocean, and Pacific ocean regions. These tropical regions suffer with an already heavy toll, and might witness potentially devastating epidemics not only in terms of morbidity and mortality but also in economical impact. For example, the 2001-2002 outbreak in Martinique touched 24000 people (6% of the island population), and led to the death of 4 victims 2. The increased general mortality during dengue epidemics is not known, and dengue prevalence is still increasing in the region. The recent outbreak of the Chikungunya virus in the Reunion Island underscores clearly that mosquito-borne viral diseases can emerge rapidly, and even worse, that no prophylactic nor therapeutic treatments are available. As the DENVs may co-circulate in the affected regions worldwide, there is a need for a coordinated therapeutic solution, simultaneously targeting all four serotypes. Successful antiviral drug-design and chemotherapy depend on answers to several questions such as: the availablility of rapid diagnostics, the technologically and scientifically feasiblility of drug-discovery and drug-design. In the case of DF, it has been demonstrated that there is a direct correlation between high viral load and the development of the more severe, life-threatening form of dengue disease. In an epidemic scenario, prophylactic mass treatment around index cases would be essential. Therefore, an efficient and safe drug, delivered early in the course of dengue disease, should not only save lives but also curb potential epidemics. We, and others such as the Novartis Institute of Tropical Diseases, have engaged into an integrated, multidisiplinary anti-DENV drug-design program, which is the main object of this project. The goal of this project is to design and develop antiviral drugs against the dengue virus, and other emerging Flavivirus, using an integrated approach which combines screening technology, organic synthesis, biochemistry, structural biology, cellular biology and virology. The origin of the project is the discovery by partner 1 of 4 antiviral candidate molecules « hits » active against the NS3 Dengue polymerase by screening of the French national compounds library (Curie Institute / Strasbourg). Our specific objectives are: - the complete biochemical characterisation of the four hits identified (partner 1). - Hit optimization/analogue production (partners 2 and 3). - Enzymatic evaluation in vitro against Flavivirus polymerases and biochemical characterisation of these synthesized compounds, SAR data (partner 1). - Study of the 'hit' molecule/targeted protein interactions, tools creation (partners 1 and 3) - in cellulo evaluation in infected cells. Cytotoxicity evaluation (partner 4). The present project is built in the context of a national anti-DENV drug discovery network made of 4 partners having complementary expertises. The network was established two years ago and its efficiency has been demonstrated by the preliminary results obtained.