New Method Detects Clusters of Viruses in Wastewater

Viruses such as human norovirus can travel in vesicles, small fluid-filled sacs that are like shipping containers for cells. Viruses hidden in these containers are often harder to detect and may be more infectious than free-floating viral material. In addition, their prevalence in the environment remains relatively unknown, raising public health concerns.

In a new studypublished in Nature Water, researchers led by a team from the George Washington University have developed an effective method for isolating and detecting these viral vesicles in wastewater. The study, "Discovery of Emerging Vesicle-Associated Viruses in Wastewater and Implications for Engineering Interventions," was led by Yun Shen, an assistant professor of civil and environmental engineering at the School of Engineering and Applied Science. Experiments were led by Yuepeng Sun, a former GW postdoctoral student, and Hongyue Zhang, a current Ph.D. student.

"Most wastewater treatment strategies are designed around the idea that viruses exist as free particles," said Yun Shen. "Our findings show that many viruses are protected inside vesicles, which can increase their survival and infectious potential and raise questions for wastewater treatment, water reuse and public health protection, as current approaches may allow viruses hidden in vesicles to escape wastewater treatment."

Although scientists are able to isolate viral vesicles from cell cultures and stool samples in the lab, recovering them from environmental sources has proved more challenging. This limitation has left a significant gap in our understanding of how these vesicles contribute to viral transmission, Shen said.

To address this, Shen and her collaborators from Tulane University, Michigan State University and the National Institutes of Health (NIH) developed a novel method for detecting viral vesicles in environmental samples and applied it to city and hospital wastewater. Their analysis revealed a substantial share of vesicle-cloaked human noroviruses in wastewater, as well as other pathogens such as rotavirus.

Norovirus, rotavirus and other pathogens that attack the intestinal tract in the human body are widely found in municipal wastewater, agriculture fields and food products. These pathogens are major drivers of gastrointestinal illness and impose substantial health and economic burdens. Understanding how these pathogens are transmitted and persist in the environment is essential for assessing the public health impact and for developing effective interventions.

The study showed:

• The new method was able to effectively isolate viral vesicles from different environmental samples.
• From the samples collected, human norovirus GII-the strain often linked to outbreaks worldwide-was most prevalent.
• The heaviest concentrations of norovirus were in the winter months, when outbreaks are more frequent.
• A number of other vesicle-cloaked viruses were present, such as rotavirus and astrovirus.

The study involved collaborators from Yale University, the National Institutes of Health, Tulane University, the University of California, Riverside and Michigan State University. Read it in Nature Water here.

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