Serotypes distribution characteristic of enterovirus in sewage in Hangzhou, Zhejiang Province from January 2023 to December 2024.

BACKGROUND

Enteroviruses (EV) represent a significant public health concern due to their widespread prevalent and ability to cause disease in humans. Due to the limitations of routine surveillance, which primarily only detect clinically symptomatic cases, environment surveillance of urban sewage has emerged as a valuable and complementary strategy for EV surveillance.

METHODS

A total of 48 sewage samples were collected monthly from two wastewater treatment plants (WWTPs) in Hangzhou, Zhejiang Province from January 2023 to December 2024. Virus isolation and direct next-generation sequencing (NGS) were performed to characterize the EV serotypes profiles in sewage. Reverse transcription polymerase chain reaction (RT-PCR) was used to amplify VP1 gene sequences for molecular epidemiological analysis of EV serotypes.

RESULTS

Ten distinct serotypes were isolated and identified from WWTP-QT and sixteen from WWTP-XS via virus isolation. EV-B was the dominant group in both treatment plants, with E3 and E11 representing the most frequently isolated serotypes. Phylogenetic analysis showed that the predominant genotypes in E3 was C6, whereas all E11 included phylogenetic analysis were classified into genotype D5. On the other hand, direct NGS uncovered as many as 108 distinct EV serotypes covering four human-infective species across both WWTPs. CVA4 and CVA6 were the dominant serotypes identified via NGS. Additionally, multiple uncommon serotypes as EV-A76, A89, A90, A92, A114, B74, B79, B98, B101, B106, B107, C96, C99, C113, C116, D70, D94, D111, D120 were detected in sewage.

CONCLUSION

Environment surveillance is an important tool for monitoring EV circulation in the population. Furthermore, direct NGS can serve as a supplementary tool to the routine virus isolation method, particularly in detecting EV serotype diversity and evolution, and identifying uncommon serotypes.