Molecular Etiology and Epidemiological Features of a Sapovirus GI.6 Diarrheal Disease Cluster in Jiangxi, China

Objective To clarify the etiological and genetic evolutionary characteristics of an acute gastroenteritis cluster epidemic caused by sapovirus in Nanchang, Jiangxi, China. Methods A total of 10 anal swab samples were collected from student and teacher cases during a gastroenteritis epidemic at a primary school in Nanchang, Jiangxi Province in November 2024. Real-time fluorescent RT-PCR was used for routine gene detection of diarrhea viruses. For the sapovirus nucleic acid-positive samples, traditional RT-PCR was used for amplification, sequence determination, splicing, and genetic evolutionary analysis. Results This epidemic cluster was formed due to contact transmission. Real-time fluorescent RT-PCR detection confirmed that 5 samples were positive for sapovirus nucleic acid, and the capsid protein gene VP1 fragments were successfully amplified. Genetic evolutionary analysis revealed that the molecular type of sapovirus was the GI.6 genotype, with 100% homology among the 5 sequences. The nucleotide homology between the sequences in this study and the sapovirus GI.6 reference sequence ranged from 97.07% to 99.12%, and the amino acid homology ranged from 96.49% to 97.37%. Amino acid variation site analysis revealed that there were 4 amino acid site substitutions between them. The closest distance of nucleotide homology was 99.12% from Zhejiang, China in 2023 (OR351089)。 Conclusion The causative agent of this epidemic cluster was identified as sapovirus GI.6, a genotype rarely reported in Jiangxi. In the future, further research on the molecular epidemiology of sapovirus with more gene sites that may mutate should be strengthened.