Global resurgence of norovirus GII.17[P17] accompanies shifting phylogeographic connectivity patterns: surveillance in Jiangsu, 2023–2025
TL;DR
Inferred phylogeographic connectivity patterns indicate that the primary centers of GII.17[P17] lineage dispersal have shifted from East Asia to Northwest Europe and carries lineage-specific amino acid substitutions in antigenic epitopes temporally associated with its global expansion.
Abstract
Norovirus GII.17[P17] has re-emerged and has been circulating globally since 2023. In Jiangsu, China, we found that its proportion increased from 2024 onward. Using local surveillance data combined with global sequences, we reconstructed the global spatiotemporal dynamics of GII.17[P17] and explored its evolution and molecular mechanisms. Samples were subjected to whole-genome sequencing using next-generation sequencing. We used bioinformatics tools to analyze the full viral protein 1 sequences for molecular evolution, spatiotemporal phylogeographic associations, and amino acid changes. From October 2024 to May 2025, 209 GII.17[P17] outbreaks were reported (approximately 26 per month), while only 23 outbreaks occurred in the full year of 2023 (fewer than 2 per month). In sporadic case surveillance, the proportion of GII.17[P17] increased from 9.6% in 2023 to 62.4% in January–May 2025. The maximum clade credibility tree showed that GII.17[P17] clustered into two large clusters. Most samples from 2024 to 2025 belonged to Lineage 3 of Cluster II. In the phylogenetic network and minimum spanning tree, we identified three core hub strains. Inferred phylogeographic connectivity patterns suggest a shift in the primary centers of viral lineage dispersal from East Asia (Cluster I, 2014–2016) to Northwest Europe (Cluster II, 2021–2025). Molecular evolutionary analysis revealed that the current dominant lineage (Lineage 3, Cluster II) exhibited an evolutionary rate of 4.126 × 10 −3 substitutions/site/year (95% HPD: 3.27–4.98 × 10 −3 ), substantially higher than the earlier Cluster I lineages (1.798 × 10 −3 ; 95% HPD: 1.41–2.19 × 10 −3 ; posterior probability >0.99; 95% HPD intervals non-overlapping). Inferred phylogeographic connectivity patterns indicate that the primary centers of GII.17[P17] lineage dispersal have shifted from East Asia (2014–2016) to Northwest Europe (2021–2025). The current dominant lineage (Lineage 3, Cluster II) exhibits an accelerated evolutionary rate, approximately 2.3-fold faster than Cluster I lineages, and carries lineage-specific amino acid substitutions in antigenic epitopes temporally associated with its global expansion. These findings highlight the value of sustained genomic surveillance in regions with high inferred phylogeographic connectivity for monitoring norovirus evolution.
