Epidemiology and genetic diversity of classic human astrovirus with whole-genome sequence analysis in inpatient children under 5 years of age in Yunnan, China.

Purpose: The aim of this study was to determine the epidemiology, incidence and genetic diversity of classic human astrovirus (HAstV) in inpatient children under 5 years of age for acute gastroenteritis (AGE).

Methods: A hospital-based surveillance study was conducted across Yunnan Province to investigate the incidence of HAstV among AGE patients. Viral RNA was extracted from stool samples collected from January 2015 to December 2023 from hospitalized children under 5 years of age with AGE. Demographic and clinical data were collected and analysed. The RNA of eligible stool samples (n = 2501) was screened via real-time RT‒PCR assays for the presence of classical HAstV via a real-time PCR diagnostic kit for rapid detection of HAstV (XABT, China). The positive HAstV samples (Ct < 25) were subjected to next-generation sequencing (NGS), and phylogenetic analysis was performed for genotypic characterization.

Results: A total of 2501 stool samples from hospitalized children < 5 years old were analysed for the presence of classic HAstV from 2015 to 2023. HAstV RNA was detected in 4.88% (122/2501) of the stool samples in the study. There were 1.46 times more male patients than female patients (1484/1017), and their HAstV detection rates were 4.58% (68/1484) and 5.31% (54/1017), respectively, with no statistically significant difference (χ = 0.688 P = 0.407). Among the patients, the average age was 12 ± 17 (monthly age, M ± Q). Children between 2 and 4 years of age were more affected by HAstVs, while the highest positivity detection rate was found in the 24-35 month age group (7.56%, 17/225). Interestingly, the detection rate of HAstV in 2019 was 17.79% (45/253), which was significantly higher than that in other years during the surveillance period (χ = 126.229, P < 0.05). The data revealed that the prevalence of HAstV was greater in the summer (10.04%, 50/498) than that in the other seasons in Yunnan. Seventeen HAstV strains were sequenced. Further analysis of the complete genome and phylogenetic analysis revealed the presence of classic HAstV-1 - HAstV-4 genotypes. HAstV-1 was the most commonly detected genotype, and all 11 HAstV-1 strains were classified to 1a subtype.

Conclusion: This study provided valuable insights into the epidemiology and genotype diversity of HAstVs in hospitalized children under 5 years of age with AGE. The results can be used in future preventive measurements and the development of effective vaccines.