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Echovirus 11 (E11) has gained attention owing to its association with severe neonatal infections. From 2018 to 2023, a surge in severe neonatal cases and fatalities linked to a novel variant of genotype D5 was documented in China, France, and Italy. However, the prevention and control of E11 variants have been hampered by limited background data on the virus circulation and genetic variance. Therefore, the present study investigated the circulating dynamics of E11 and the genetic variation and molecular evolution of genotype D5 through the collection of strains from the national acute flaccid paralysis (AFP) and hand, foot, and mouth disease (HFMD) surveillance system in China during 2000-2022 and genetic sequences published in the GenBank database. The results of this study revealed a prevalent dynamic of E11 circulation, with D5 being the predominant genotype worldwide. Further phylogenetic analysis of genotype D5 indicated that it could be subdivided into three important geographic clusters (D5-CHN1: 2014-2019, D5-CHN2: 2016-2022, and D5-EUR: 2022-2023). Additionally, variant-specific (144) amino acid mutation sites and positive-selection pressure sites (132, 262) were identified in the VP1 region. Cluster-specific recombination patterns were also identified, with CVB5, E6, and CVB4 as the major recombinant viruses. These findings provide a preliminary landscape of E11 circulation worldwide and basic scientific data for further study of the pathogenicity of E11 variants.

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Objective To understand the molecular epidemiological characteristics of Norovirus outbreaks and the genome evolution of Norovirus epidemic strains in Hainan Province from 2020 to 2022.Methods The information and samples have been collected from the norovirus outbreaks from 2020 to 2022.Norovirus was detected by using the real-time PCR in these samples,then the detected sequences were amplified the analyzed.The Norovirus se-quences of 8 strains had been amplified and analyzed.Results From 2020 to 2022,39 gastroenteritis outbreaks were reported,and 25 outbreaks caused by Norovirus which mainly occurred in childcare institutions and schools(20/25,80％).The Norovirus outbreaks were mainly concentrated in counties around Haikou(northeast),which including Ding'an(5 cases),Wenchang(4 cases),Chengmai(4 cases),and Lingao(3 cases);following by western regions which included Baisha(2 cases),Ledong(2 cases),and Dongfang(3 cases).1 case was in Wanning in the southeast.Among individuals aged 2-17,the positive proportion of Norovirus in males was higher than that in females.Among individuals aged over 55,the proportion of Norovirus positive in females was higher than that in males.The gender of positive samples among individuals aged 18-40 was related to their profession.According to RT-PCR typing and sequencing,GⅡ group Norovirus were classified in13 outbreaks.There were 4 genotypes detected.GⅡ.2[P1 6]was the main epidemic strain with 60％(9/13),and the other three genotypes were GⅡ.4 Sydney[P31](15.4％,2/13)GⅡ.4 Sydney[P16](7.7％,1/13)and GⅡ.3[P12](7.7％,1/13).Further genic analysis of 8 Norovirus strains showed that all of them were still in the same branch as the previ-ous strain,and all exhibited a certain amount of amino acid variation.Conclusion Norovirus is the main pathogen of gastroenteritis outbreaks in Hainan province,and the main epidemic strain is GⅡ.2[P16].It is necessary to continue to strengthen the monitoring that provides scientific evidence for the prevention and control of norovirus out-breaks in Hainan region.