Achievements and Approaches in the Search for Small-Molecule Dengue NS2B/NS3 Inhibitors

With the escalation of viral infections in recent decades, including the COVID- 19 pandemic, viral infectious diseases have increasingly become a global concern, attracting significant attention. Among many viral epidemics, the dengue virus, an RNA virus from the Flaviviridae family, has been reported by the WHO as one of the most prevalent mosquito-borne diseases, infecting roughly 400 million people yearly and spreading across all continents worldwide. In the last two decades, researchers from academia and industry have diligently studied many aspects of the virus, including its structure, life cycle, potential therapeutic agents, and vaccines. Dengvaxia® and Qdenga®, approved vaccines for DENV-4, have been a milestone in dengue prevention and treatment. However, these vaccines have some noticeable drawbacks, including Dengvaxia® being a monovalent vaccine against DENV-4 with a risk of severe dengue infection following the first use, Qdenga® being mainly effective for all 4 serotypes only in the cases of previously infected patients while being effective against only DENV-1 and DENV-2 in dengue-naïve patients. Additionally, no drug against dengue has been approved. Thus, numerous screening campaigns have been conducted on both natural and synthesized substances to search for anti-dengue agents, especially those targeting the virus's key protease (NS2B/NS3), to mitigate the dengue fever epidemic. As hit screening is only the first step in the drug discovery and development cycle, subsequent in-depth analyses (using a wide range of approaches from computational simulations to protein-ligand co-crystallization) have been conducted to provide more insights into the characteristics of optimal DENV NS2B/NS3 protease inhibitors. This review discusses recent discoveries in the search for novel inhibitors and highlights the importance of understanding the structural relationship between hits and the NS2B/NS3 protease for effective lead optimization.