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Updated: Jul 10, 2026

Production of Human Norovirus Protruding Domains in E. coli for X-ray Crystallography
Published on: April 19, 2016
Levan produced by probiotic Bacillus subtilis CU1 inhibits human norovirus GII.4 replication in zebrafish via
Siyu Chen1, Malcolm Turk Hsern Tan2, Jillinda Yi Ling Toh2
1Department of Food Science and Technology, Faculty of Science, National University of Singapore, Singapore; Department of Food Science and Technology, National University of Singapore (Suzhou) Research Institute, Suzhou, Jiangsu, China.
Abstract:
This study investigated the antiviral potential of exopolysaccharides (EPSs) from probiotic bacteria against human noroviruses (hNoVs). EPSs from Bacillus subtilis CU1, B. subtilis R0179, and Lactiplantibacillus plantarum 299V were initially evaluated using Tulane virus (TV), a cultivable hNoV surrogate. Although EPSs reduced the cytopathic effects caused by TV infection, no clear dose-response relationship was observed. In contrast, the zebrafish model enabled testing of hNoV strains and revealed a distinct anti-hNoV GII.4 activity specific to EPS from B. subtilis CU1. This effect was virus genotype- and bacteria strain-specific: EPSs from B. subtilis R0179 and L. plantarum 299V showed no activity, nor did CU1 EPS affect hNoV GII.2 or GII.17. The major EPS fraction was identified as a levan composed of β-(2,6)-linked Fruf, which exhibited high binding affinity to hNoV GII.4 virus-like particles and P particles, confirmed by saliva-binding ELISA and bio-layer interferometry. Finally, B. subtilis CU1 was used to ferment carrot juice. The antiviral effect of EPS produced by B. subtilis CU1 in fermented carrot juice was validated, and the EPS yield was optimized accordingly. These findings highlight B. subtilis CU1 EPS as a promising anti-hNoVs agent and demonstrate carrot juice as a safe, cost-effective substrate for scalable production of functional probiotic EPSs.
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