NUS scientists uncover natural compound that fights norovirus infection

NUS scientists uncover natural compound that fights norovirus infection

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Stopping viruses before they strike is a key challenge in public health. A research team led by Associate Professor Li Dan from the Department of Food Science and Technology at National University of Singapore's Faculty of Science has identified a natural probiotic-derived compound that can potentially prevent human norovirus infections by blocking the virus from attaching to their host cells in the body.

Norovirus is the leading cause of acute gastroenteritis worldwide and is responsible for large outbreaks in hospitals, schools,and cruise ships. There are currently no approved antiviral drugs or vaccines, and treatment is largely limited to managing symptoms.

Progress in developing targeted interventions had been challenging, as the virus could not be reliably cultivated in laboratory settings until 2023, when Assoc Prof Li and her team established a zebrafish embryo model that enables human norovirus to be grown and studied in the laboratory, overcoming a major bottleneck in the field. The model allows researchers to examine viral behaviour and evaluate potential interventions more consistently than earlier systems dependent on scarce human tissue samples.

A safer alternative for vulnerable groups

In this study published in Food Microbiology on 25 October 2025, researchers focused on substances known as exopolysaccharides, which are complex sugars naturally secreted by bacteria. Unlike live probiotics which contain bacterial cultures, these compounds do not contain living microorganisms. This makes them potentially safer for vulnerable groups, including people with weakened immune systems who are often advised to avoid live probiotic products.

In laboratory tests, the team found that an exopolysaccharide produced by a probiotic bacterium, Bacillus subtilis CU1, binds directly to the norovirus particle. Instead of destroying the virus or activating the immune system, the compound acts as a physical barrier at the earliest stage of infection. The protective effect was observed against the GII.4 norovirus strain, responsible for most outbreaks globally.

"Our findings show that it is possible to block the virus before it can establish an infection," said Assoc Prof Li. "This could be especially useful for people who cannot rely on strong immune responses, such as the elderly, young children, or individuals with weak immune systems."

From laboratory discovery to practical application

To explore practical use, the team demonstrated that the probiotic bacterium can ferment carrot juice to produce high levels of the protective compound without losing its ability to block the virus. This approach offers an affordable, food-based method for producing functional food products or supplements that help prevent disease.

Further studies are needed to ensure long-term safety and effectiveness before the findings can be developed into consumer products or used in clinical settings.