Human noroviruses (hNoVs) cause heavy disease burden worldwide and there is no clinically approved vaccination or antiviral hitherto. In this study, with the use of a zebrafish larva in vivo platform, we investigated the anti-hNoV potentials of fucoidan (from brown algae Fucus vesiculosus) and 2′-Fucosyllactose (2′-FL). As a result, although both fucoidan and 2′-FL were able to block hNoV GII.4 virus-like particle (VLPs) from binding to type A saliva as expected, only fucoidan, but not 2′-FL, was able to inhibit the replication of hNoV GII.P16-GII.4 in zebrafish larvae, indicating the possible needs of higher molecular weights for fucosylated carbohydrates to exert anti-hNoV effect.

Aims To compare the heat stability of two globally prevalent human norovirus (HuNoV) strains (GII.2[P16] and GII.4[P16]) and a commonly used HuNoV surrogate, Tulane virus (TV). Methods and Results With the use of a newly developed zebrafish larvae platform, we measured the change of infectivity of HuNoV GII.2[P16] and GII.4[P16] toward mild heat treatment at 55°C for 5 min. TV was tested with the same experimental design. As a result, the virus infectivity measurement clearly indicated the higher heat resistance of HuNoV GII.2[P16] (no reduction) than GII.4[P16] (>0.8‐log TCID50 ml−1 reduction) and TV (2.5‐log TCID50 ml−1 reduction). Further exploration revealed higher virus structural stability of HuNoV GII.2 than GII.4 strains by the use of different clinical samples with different evaluation methods. Conclusion The inactivation data generated from the surrogate virus TV cannot be used directly to describe the inactivation of HuNoV. The phylogenetic classification of HuNoVs may correlate with the virus stability and/or circulation dynamics. Significance and Impact of the Study This study is expected to serve as an important reference when revisiting the numerous previous data evaluating HuNoV inactivation conditions in foods with the use of TV as the cultivable surrogate or with genuine HuNoV but using molecular methods. The higher resistance of NoV GII.2 strains than GII.4 strains toward inactivation treatment supplies a possible explanation for the global re‐emerging of NoV GII.2 epidemic in recent years.

Human noroviruses (hNoVs) are the most important foodborne viruses, and soft berries are one of the most common food sources of hNoV outbreaks and contamination. This paper presents a human volunteer study in order to investigate the correlation between molecular detection results of hNoV in berries with the public health risks. The participants with diverse histo-blood group antigens (HBGAs) phenotypes were required to consume self-purchased berries and meanwhile submit aliquots of the products for reverse transcription-quantitative polymerase chain reaction (RT-qPCR) detection. As a result, none of the 20 participants reported any hNoV infection-like symptoms after six independent consumptions (120 consumptions in total). In contrast, within the 68 berry samples with >1% virus recoveries, 28 samples were detected to be positive for hNoV GI and/or GII (the positive rate at 41%). All of the positive signals were below the limit of quantification (<120 genome copies/g) except one fresh strawberry sample at 252 genome copies/g. It is expected that this study would contribute to the definition of quantitative standards for risk assessment purposes in the future.

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