bDengue virus (DENV) causes disease globally, resulting in an estimated 25 to 100 million new infections per year. No effective DENV vaccine is available, and the current treatment is only supportive. Thus, there is an urgent need to develop therapeutic agents to cure this epidemic disease. In the present study, we identified a potential small-molecule inhibitor, BP13944, via highthroughput screening (HTS) of 60,000 compounds using a stable cell line harboring an efficient luciferase replicon of DENV serotype 2 (DENV-2). BP13944 reduced the expression of the DENV replicon reporter in cells, showing a 50% effective concentration (EC 50 ) of 1.03 ؎ 0.09 M. Without detectable cytotoxicity, the compound inhibited replication or viral RNA synthesis in all four serotypes of DENV but not in Japanese encephalitis virus (JEV). Sequencing analyses of several individual clones derived from BP13944-resistant RNAs purified from cells harboring the DENV-2 replicon revealed a consensus amino acid substitution (E66G) in the region of the NS3 protease domain. Introduction of E66G into the DENV replicon, an infectious DENV cDNA clone, and recombinant NS2B/NS3 protease constructs conferred 15.2-, 17.2-, and 3.1-fold resistance to BP13944, respectively. Our results identify an effective small-molecule inhibitor, BP13944, which likely targets the DENV NS3 protease. BP13944 could be considered part of a more effective treatment regime for inhibiting DENV in the future.
D engue virus (DENV) (serotypes 1 to 4) belongs to the familyFlaviviridae, a group of enveloped RNA viruses that includes the genera Hepacivirus, Flavivirus, and Pestivirus. The genus Flavivirus consists of arthropod-borne disease agents such as yellow fever virus (YFV), Japanese encephalitis virus (JEV), West Nile virus (WNV), tick-borne encephalitis virus (TBEV), and DENV (1). More than 70 members of the Flavivirus genus are important human pathogens that cause significant morbidity and mortality (2). DENV is a public health threat to an estimated 2.5 billion people living in areas where dengue is epidemic, leading to 50 to 100 million human infections each year (3, 4). DENV infection frequently leads to dengue fever, life-threatening dengue hemorrhagic fever (DHF), or dengue shock syndrome (DSS) (5-7). Approximately 500,000 cases of DHF and DSS have been reported among more than 100 countries, causing approximately 12,500 deaths per year (3). Despite the tremendous efforts invested in anti-DENV research, no clinically approved vaccine or antiviral therapeutic agents are available for humans, and disease treatment is limited to supportive care (4,8,9). Considering the spread of this epidemic and the severity of DENV, an effective anti-DENV drug is urgently needed.DENV is an enveloped RNA virus consisting of a 10.7-kb single-stranded, positive-polarity RNA genome associated with multiple copies of capsid proteins. DENV RNA is translated as a single polyprotein upon entering the host cell and is cleaved by host proteases and the virus-encoded two-component protease (NS...