Emerging Waterborne Pathogen of Vesicle-cloaked Virus Clusters
Viruses have traditionally been viewed as individual infectious particles released from host cells by lysis, particularly in the case of non-enveloped viruses. Recent discoveries challenge this paradigm: clusters of viruses—including norovirus, rotavirus, enteroviruses, and hepatitis A and E viruses—can be packaged within extracellular vesicles and released nonlytically.
Our research examines these vesicle-cloaked virus clusters, or viral vesicles, as emerging pathogenic units in water and wastewater. Using murine norovirus and rotavirus as models, we investigate their environmental persistence, infectivity, and response to disinfection. We have shown that viral vesicles can remain intact and infectious in freshwater and wastewater for extended periods and are more resistant than free viruses to conventional and emerging disinfectants, including free chlorine, UV254, solar UVB, and reactive oxygen species. Their enhanced infectivity and resilience arise partly from the protective vesicle membrane and the en bloc delivery of multiple virions to host cells.
We also isolate viral vesicles from wastewater, together with cell-derived viral vesicles, to study their mechanical properties—particularly viscoelasticity—and their role in environmental persistence. The increased viscoelasticity of environmentally isolated vesicles is likely associated with environmental constituents. Chemical intercalation into vesicle membranes can substantially alter viscoelasticity and destabilize the membrane; detergents provide one example. Disrupting the membrane structure eliminates the vesicle-associated state and can reduce associated microbial risks.
By establishing viral vesicles as environmentally persistent and disinfection-resistant pathogenic units, our work challenges the conventional assumption that free virions are the primary form of viral transmission in water. These mechanistic insights provide a foundation for designing innovative treatment strategies and improving microbial risk assessment for safe water reuse.
