[Molecular epidemiological characteristics of Sapovirus infection in pediatric diarrhea cases aged 5 years and under in Guangdong Province, 2022-2024].

Objective: To analyze the incidence and genetic characteristics of Sapovirus infection in pediatric diarrhea cases aged ≤5 years in Guangdong Province. Methods: Epidemiological data and stool samples were collected from hospitalized children aged ≤5 years with diarrhea in Guangdong between January 2022 and December 2024. Sapovirus RNA detection from stool samples was conducted by using real-time RT-PCR, and partial VP1 region was amplified and sequenced. Phylogenetic tree analysis was conducted to characterize the genotype of each sequence. Whole-genome sequencing of samples with predominant GⅠ.1 genotype were conducted to analyze its mutation features. Results: In 2 080 pediatric diarrhea cases aged ≤5 years, the positive rate of Sapovirus was 2.45% (51/2 080). The positive rate in boys and girls were 2.20% (28/1 271) and 2.84% (23/809) respectively. The positive rate was highest in age group 13-24 months (4.40%, 22/500), and the detection peak occurred during October-December. Partial VP1 gene sequences were obtained from 31 out of 51 cases, with the GⅠ.1 genotype being predominant (80.65%, 25/31). Phylogenetic analysis indicated close evolutionary relationships among GⅠ.1 strains. Whole-genome sequencing found some amino acid substitutions at multiple conserved sites in GⅠ.1 genotype, and its mutation characteristics were highly consistent with those of the strains circulating in recent years. Conclusions: From 2022 to 2024, Sapovirus infection caused diarrhea occasionally in children aged ≤5 years in Guangdong. Sapovirus GⅠ.1 was the predominant pathogen, and the strains had close evolutionary relationship. It is necessary to further strengthen local surveillance and molecular epidemiological characterization of Sapovirus to provide evidence for epidemic trend analysis and early warning of potential outbreaks.