AsianScientist (Mar. 30, 2026)–Human Norovirus (HuNoV) is the leading cause of acute gastroenteritis worldwide. Symptoms of norovirus include an abrupt onset of diarrhoea and vomiting. The World Health Organisation (WHO) estimates that there are approximately 685 million norovirus cases each year, including 200 million in children under five.
This virus is responsible for around 200,000 deaths annually, with 50,000 of those being children, predominantly affecting low-income countries. The economic burden of norovirus is estimated to be $60 billion globally due to healthcare costs and economic losses. In 2023, researchers in Singapore successfully propagated human norovirus using zebrafish embryos, creating an important model to assess virus inactivation methods for the water treatment and food industries.
However, progress in developing antiviral treatments and vaccines has been hindered by the absence of a robust reverse genetics system. Reverse genetics systems are powerful tools used to understand how viruses replicate and cause disease. They allow researchers to explore gene functions by modifying individual genes and observing the outcomes, creating recombinant viruses—hybrid viruses formed through genetic recombination, either naturally or through laboratory engineering.
Now, scientists at the University of Osaka have successfully overcome this long-standing barrier to norovirus research by establishing a simple and efficient research system for human norovirus. Their findings were published in the Proceedings of the National Academy of Sciences.
The University of Osaka team applied virological techniques to a zebrafish model to create a novel reverse genetics system capable of producing infectious human noroviruses. To establish this system, scientists first developed a HuNoV propagation model in zebrafish based on previous studies. They then directly injected norovirus cDNA clones into zebrafish embryos, generating infectious recombinant viruses, and eliminating the need for cultured cells.
cDNA is synthetic DNA created from specific mRNA through a reaction involving the enzyme reverse transcriptase. While DNA contains both coding and non-coding sequences, cDNA includes only the coding sequences and is often synthesised for gene cloning and research purposes. The research team demonstrated the capabilities of this newly developed system by generating genetically manipulated noroviruses with specific mutations or tagged with reporter genes.
Reporter genes, such as those producing chemiluminescent molecules, can label the virus and provide insight into its activity and localisation within host cells, allowing for visualisation of the virus in action.
This manipulation of the virus enables in-depth investigations into the mechanisms of viral replication and pathogenesis. “This will also allow the development of novel vaccines with controlled antigenicity and pathogenicity,” said senior author and associate professor of the Department of Virology, Research Institute for Microbial Diseases, The University of Osaka, Takeshi Kobayashi.
This research provides a practical and efficient approach for developing HuNoV vaccines and antivirals.
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Source: The University of Osaka; Image: Ariaarmoko/Freepik
This article can be found at Recovery of infectious recombinant human norovirus using zebrafish embryos
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
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