Cryo-EM structures of herpesvirus glycoprotein complexes in native membranes: insights into viral entry and immunity

About This Grant

Varicella-zoster virus (VZV) is a human alphaherpesvirus of medical importance that can have severe outcomes in immunocompromised children and adults, causes debilitating diseases such as post herpetic neuralgia, and is linked to stroke. Like other herpesviruses, VZV relies on multiple glycoproteins for cell entry, tropism, and immune evasion, but their structural mechanisms remain poorly defined. Among these, gB and gH-gL constitute the core fusion machinery required for cell entry, while gE/gI plays a key role in viral replication and immune recognition. Despite their essential functions, high-resolution structures of complete glycoprotein complexes remain unresolved, limiting our understanding of herpesvirus membrane fusion and immune targeting. This study will leverage CyclApol-based membrane extraction and single-particle cryo-electron microscopy (cryo-EM) to define previously unobserved near-atomic resolution structures of VZV glycoprotein complexes in their native membranes. We will determine the structures of gB/gH-gL, providing critical insights into herpesvirus fusion, and gE/gI, defining its role in viral spread and antibody recognition. Guided by our strong preliminary data we propose to pursue two aims: (1) To determine the gB/gH-gL fusion complex structure and define its relationship to function; (2) To determine the structure of the gE/gI complex independently or interacting with antibodies. Preliminary data confirm the successful purification of both gB/gH-gL and gE/gI complexes from VZV-infected cells, demonstrating the feasibility of their structural determination. Our approach overcomes the limitations of computational modeling based on AlphaFold and similar platforms, circumventing their inability to accurately predict dynamic protein-protein interactions within membrane-associated complexes. By capturing glycoproteins in their native lipid environment, we will provide a structural framework for understanding viral entry and immune recognition at near-atomic resolution. These studies will set the stage for new approaches in herpesvirus structural biology, enabling the mechanistic understanding of membrane fusion, viral spread, and immune recognition at near-atomic scales while laying the groundwork for rational vaccine design and targeted antiviral therapies.