Viscoelasticity of Vesicle-Cloaked Virus Clusters: Insights into Environmental Persistence.

Vesicle-cloaked virus clusters, or viral vesicles, represent an emerging pathogenic form of enteric viruses, exhibiting enhanced infectivity, environmental persistence, and resistance to disinfection compared to free viruses. Their unique vesicle architecture and mechanical properties likely play a critical role in maintaining structural integrity and shielding encapsulated virions from environmental stressors. Here, we employed atomic force microscopy to characterize the topography and viscoelasticity of viral vesicles from cell cultures, clinical stool, and municipal wastewater. When immobilized on a substrate, the vesicle height remained relatively consistent across origins, whereas the lateral size varied substantially. Viscoelastic properties, characterized by short-term stiffness, long-term stiffness, and dissipation coefficient, were comparable among norovirus, rotavirus, and coxsackievirus B3 vesicles derived from diverse host cells but differed significantly in vesicles isolated from stool and raw wastewater. These differences likely arise from interactions between environmental constituents and conditions in these matrices and the vesicle membranes. A clear decline in vesicle viscoelasticity was also observed during the wastewater treatment process. In summary, these results indicate that viral vesicle viscoelasticity is not a fixed intrinsic property but is strongly influenced by environmental conditions, with complex matrices reshaping the mechanical behavior, persistence, and associated environmental risks.