Phylogenetic analysis of human norovirus (HNoV) genogroup I (GI) nucleotide sequences isolated in this study.

<p>Phylogenetic tree based on partial capsid gene sequences (a). Clusters of GI.4 (b) and GI.5 (c) sequences are depicted separately. GII.1 (GenBank ID; U07661) was used as the outgroup reference sequence. Norovirus sequences isolated in this study are marked with open circles (○, estuary) and filled circles (●, inflow stream). Suffixes (_1, _2 and so forth) indicate different sequences originating from a single sample. Bootstrap values ≥70 are shown at each branch, indicating groupings with significant support. The scale bar represents nucleotide substitutions per site.