Characteristics and VP1 gene of herpangina-related enterovirus detected in a sentinel hospital in Shanghai, 2020–2021

Objective To analyze the epidemiological and VP1 gene characteristics of the main pathogens detected in herpangina cases in a sentinel hospital in Shanghai, 2020−2021, and provide reference data for the prevention and control of herpangina.

Methods Clinical samples and basic information of herpangina cases were collected in a sentinel hospital in Shanghai from 2020 to 2021 for a descriptive statistical analysis. Real-time quantitative polymerase chain reaction (PCR) was used for enterovirus serotype identification. The positive samples were subjected to virus isolation, VP1 gene sequencing, gene evolution analysis, and nucleotide and amino acid homology analysis.

Results In 155 clinical samples of herpangina cases, 95 were positive for enteroviruses. The incidence rate was highest in preschool children aged 3−6 years with the cases accounting for 57.90% of the total confirmed cases. Coxsackievirus (Cox) A6 and Cox A4 were the predominant serotypes causing herpangina in 2020 and 2021 respectively, with detection rates of 33.70% and 29.50%. No cases of enterovirus (EV) 71 or Cox A5 infections were found. Based on the VP1 gene segment, the genotypes of Cox A4, Cox A6, EV71, Cox A10, and Cox A16 were C2 Cluster1, D3, C4a, C, and B1b, respectively. The nucleotide homologies between the strains isolated from the herpangina cases and the main circulating strains in China were 92.60%−96.10%, 89.70%−97.00%, 92.00%−94.60%, 90.70%−97.00%, and 92.20%−93.70%, respectively. The amino acid homologies were 92.90%−96.20%, 97.20%−99.70%, 98.30%−99.30%, 91.10%−97.10%, and 96.00%−97.10%, respectively.

Conclusion During 2020−2021, the surveillance in a sentinel hospital in Shanghai indicated that preschool children aged 3−6 years were the most susceptible population to herpangina. Cox A6 and Cox A4 were the main serotypes causing herpangina, Cox A4 became the predominant serotype in 2021. The isolated enteroviruses showed high homologies with the predominant circulating strains in China. Continuous surveillance for the pathogen spectrum changes of herpangina and virus genomic characteristics has reference value for understanding virus transmission and formulating prevention and control strategies.