Year: 2025
Type: article
Abstract: Introduction: Recent sentinel surveillance has revealed a rising prevalence of human adenovirus type 21 (HAdV-21) among HAdV infections in China. This study aimed to elucidate the molecular features of currently circulating HAdV-21 strains in China. Methods: Whole-genome sequencing (WGS) was performed on 23 HAdV-21 strains isolated from acute respiratory infection cases, 56.5% involving lower respiratory tract infections, across 7 Chinese sentinel surveillance provincial-level administrative divisions (PLADs) (2023-2024). These sequences, along with 50 previously reported HAdV-21 genomes from 6 countries (1956-2019), were integrated into a WGS dataset for comprehensive phylogenetic, genetic variation, and recombination analyses. Results: WGS categorized the HAdV-21 strains into 3 subtypes: HAdV-21a, HAdV-21b, and historical HAdV-21p (isolated in the 1950s). HAdV-21a (1956-2024, involving 5 of the 6 countries) and HAdV-21b (2005-2024, involving 3 of the 6 countries) exhibited extensive spatiotemporal distributions. Recent Chinese strains (2023-2024) belonged to HAdV-21a and HAdV-21b (HAdV-21a/b), showing extremely high genetic homology with Chinese 2019 strains (genetic distance: 0.00007) and global strains (distance: <0.00040). Phylogenetic analysis confirmed that HAdV-21a/b shared a common ancestor and maintained a highly conserved genome despite decades of circulation. Sequence variation analysis identified shared and subtype-specific mutations in these two subtypes. Recombination pattern analysis further revealed that HAdV-21a/b acquired an HAdV-3-derived fragment in the E4 region (breakpoint: nt32,843). Conclusions: Recombinant HAdV-21a/b subtypes have co-circulated in China in recent years with remarkable genetic conservation. Enhanced surveillance is essential to quantify associated disease burden and guide targeted prevention and control strategies.
Source: China CDC Weekly
Authors: Jin Yali, Mao Naiying, Ma Xueping, Zhao Linqing, Sun Liwei, Deng Jikui, Liang Shu, Xu Hongmei, Li Xin, Zhu Chunyu, Xia Baicheng, Cui Aili, Zhang Yan, Zhu Zhen
Institutions: Chinese Center For Disease Control and Prevention, National Institute for Viral Disease Control and Prevention, Ningxia Center for Diseases Prevention and Control, Capital Institute of Pediatrics, Changchun Children's Hospital, Shenzhen Children's Hospital, Gansu Provincial Center for Disease Control and Prevention, Children's Hospital of Chongqing Medical University, Chongqing Medical University, Shenyang Center for Disease Control and Prevention
Language: English
Subfield: Epidemiology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W4415764720
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