Molecular characterization of a rare norovirus GII.8[P8] strain detected during pediatric acute gastroenteritis surveillance in Harbin, China.

Norovirus is a major causative agent of pediatric acute gastroenteritis, whereas GII.8[P8] represents a rare, non-dominant genotype with limited publicly available whole-genome data. We characterized a GII.8[P8] norovirus strain, Harbin-Nov-076-2022, detected through routine surveillance of pediatric acute gastroenteritis in Harbin, China. The strain was obtained from a stool sample of a 15-month-old female patient and subjected to whole-genome sequencing using the DNBSEQ-T7 platform. Integrated analyses included phylogenetic reconstruction, amino acid entropy profiling, selection pressure assessment, homology modeling of the capsid P protein, and B-cell epitope prediction. The near-complete genome of Harbin-Nov-076-2022 is 7486 nt in length, with a GC content of 53.81%, and displays the canonical three-open-reading-frame organization of human noroviruses. The sequence was deposited in GenBank under accession number PV416744. Phylogenetic analysis assigned the strain to the GII.8[P8] lineage, with the highest nucleotide identity of 97.52% to the Thai 2018 strain GII/Hu/TH/2018/GII.8[P8]/B6213 (ACCN: OR546393). Amino acid variability was highest in the VP2 region, with three variable sites (residues 15, 122, and 229) identified among the aligned GII.8[P8] VP2 sequences, whereas selection pressure analysis indicated that the genome was largely constrained by purifying selection. Same-template P-domain modeling predicted localized sequence-associated variations in the P2 subdomain and HBGA-binding-associated surface loops, with 59 predicted B-cell epitopes. These findings expand whole-genome evidence for rare GII.8[P8] norovirus in Northeast China and provide regional genomic data for molecular surveillance, evolutionary assessment, and antigenic characterization of non-dominant norovirus genotypes.