Genomic Adaptations and Evolutionary Trends in the Emerging Norovirus GII.17

Background Norovirus genogroup II genotype 4 (GII.4) has historically dominated global epidemics over the past decades. However, genogroup GII.17 has demonstrated significant evolutionary and epidemiological dynamics, particularly with the emergence of the GII.17 Kawasaki strain during the 2014 outbreaks in Asia. In 2024, GII.17[P17] re-emerged with evidence of global dissemination. Despite its public health relevance, the origin, evolutionary characteristics, and genomic drivers of GII.17[P17] remain incompletely understood. Results Our analysis revealed that GII.17[P17] rapidly emerged during 2014–2015, forming two distinct evolutionary clusters, with early divergence observed in South Korea and subsequent separation into clusters in China and Japan. Recent data indicate that GII.17[P17] has continued to evolve, with geographic-specific differences in its evolutionary patterns. Both the VP1 and VP2 genes show signatures of positive evolution, with distinct mutational characteristics between clusters. VP2 appears to play a significant role in recent diversification, suggesting functional relevance beyond its traditionally recognized role. Conclusion These findings highlight the importance of continuous genomic surveillance with an emphasis on whole-genome sequencing to monitor emerging norovirus variants. A better understanding of the evolutionary trajectories and functional mutations in GII.17[P17] is critical to inform outbreak preparedness, guide vaccine development, and improve control strategies against future norovirus epidemics.