Antigenic and Glycan-Binding Characteristics of Norovirus GII.20 Capsid Protein VP1

Norovirus (NoV) is the major pathogen causing acute gastroenteritis globally. The capsid protein VP1 of GII.20 NoV is closely related to that of the prevalent GII.4 genotype. In this study, we explored the antigenic and glycan binding characteristics of GII.20 VP1. GII.20 VP1 was obtained and presented virus-like particles (VLPs) with a diameter of approximately 38 nm. Polyclonal sera against GII.20 VLPs showed good binding activity even at a dilution of 1:819200 and presented certain binding to GII.4 VLP. In addition, polyclonal sera against GII.4 VLPs showed binding to GII.20 VLP. Polyclonal sera exhibited neutralization effects on GII.20 and GII.4 VLPs in the blocking assay. Furthermore, GII.20 VLP bound to A/B/O type saliva. Sequence analyses revealed that the amino acids in the presumed glycan binding region of GII.20 was similar to that of GII.4. The structure model of the GII.20 P protein showed the greatest structural similarity with those of GII.17 and GII.4 P proteins. In summary, GII.20 VP1 exhibited cross-antigenicity and similar saliva-binding characteristics to that of the prevalent GII.4, which may help explain the low prevalence of GII.20. Considering the high impact of GII.4 NoVs, further surveillance is necessary to monitor the evolution and variation of GII.20 NoV.