Traditional antiviral drugs mostly act through an ‘occupancy-driven’ mode of action, in which they inhibit viral infection by occupying functional sites on viral or host targets. However, these drugs still face challenges such as drug resistance, toxicity and side effects, and insufficient broad-spectrum activity. Therefore, there is an urgent need to develop antiviral agents with new modes of action to address potential emerging and re-emerging viral infectious diseases. In recent years, proximity-inducing strategies represented by molecular glues have enabled the regulation of target functions by modulating protein-protein interactions, and have been widely applied in fields such as oncology. However, their application in antiviral research remains very limited, and the reported antiviral molecular glues have all been identified through serendipitous discovery. Therefore, the rational design of molecular glues targeting viral proteins is of great significance for the development of novel antiviral therapeutics.

In a recent study published in Advanced Science, a collaborative team of researchers led by LIU Hong from Shanghai Institute of Materia Medica, CAS, and ZHOU Xi from Wuhan Institute of Virology, CAS, developed antiviral molecular glues targeting the dimerization interface of 3A through a rational drug design strategy. These molecular glues induce the formation of nonfunctional, aberrant 3A dimers, thereby inhibiting its function as a viral suppressor of RNAi (VSR), promoting RNAi-mediated degradation of the viral genome, and suppressing viral replication and infection. The optimal molecular glue VTP-32 exhibited potent and broad-spectrum antiviral activity against multiple enteroviruses, including groups A, B, and D, both in vitro and in vivo, while showing a favorable safety profile. This study provides a new therapeutic target and a novel molecular entity for the development of broad-spectrum anti-enteroviral drugs.

Enteroviruses commonly infect children and can cause severe or even fatal neurological diseases, posing a serious public health concern. However, effective strategies for the prevention and treatment of enteroviral infections remain very limited. Previous studies by ZHOU Xi group at the Wuhan Institute of Virology revealed that the enteroviral nonstructural protein 3A binds dsRNA generated during viral replication through homodimerization, thereby blocking the Dicer-dependent host RNAi-mediated antiviral innate immune pathway and promoting viral replication and infection. Based on the mechanism by which 3A homodimerization suppresses RNAi-mediated antiviral immunity, we rationally designed molecular glues targeting the dimerization interface of the 3A protein. These molecular glues were designed to induce the formation of nonfunctional, aberrant 3A dimers, inhibit its function as a viral suppressor of RNAi, promote RNAi-mediated degradation of the viral genome, and ultimately block viral replication and infection.

Through rational drug design and systematic structural optimization, we identified the molecular glue VTP-32, which exhibited potent and broad-spectrum anti-enteroviral activity against multiple enteroviruses, including EV-A71, CV-A10, CV-A16, Echo 11, and EV-D68, while showing a favorable safety profile with CC50 values of over 500 μM. Mechanistic studies demonstrated that VTP-32 can simultaneously bind two 3A proteins and induce the formation of an aberrant sandwich-like ‘3A-VTP-32-3A’ complex. This complex loses the ability to protect viral dsRNA, thereby restoring the host RNAi-mediated antiviral immune response.

In an EV-A71-infected suckling mouse model, VTP-32 dose-dependently improved mouse survival, alleviated clinical symptoms, and significantly reduced viral loads in multiple tissues, including muscle, brain, lung, and heart, demonstrating favorable in vivo antiviral efficacy.

This study innovatively applied the rational design of antiviral molecular glues to target the enteroviral RNAi suppressor 3A protein, expanding the application of molecular glues in antiviral research and providing a novel mechanism and a new molecular entity for the development of broad-spectrum therapeutics against enteroviral infections.

Rational design of broad-spectrum anti-enteroviral molecular glues targeting enteroviral RNAi suppressors (image by LIU Hong group)

DOI: https://doi.org/10.1002/advs.75317

Link: https://advanced.onlinelibrary.wiley.com/doi/10.1002/advs.75317

Keywords: broad-spectrum anti-enterovirus; molecular glues; rational design; viral suppressor of RNAi (VSR)

Contact:

DIAO Wentong

Shanghai Institute of Materia Medica

E-mail: diaowentong@simm.ac.cn