Zang Jia, Xing Yueping, Zhang Hongkai, Wu Yanshi, Ya Xuerong, Shen Qiang, Dong Zefeng
Suzhou Center for Disease Control and Prevention, Suzhou, 215004, China.
Virol J. 2025 Jul 15;22(1):243. doi: 10.1186/s12985-025-02870-z.
Human adenoviruses (HAdV) comprises a genetically diverse group of double-stranded DNA viruses strongly associated with influenza-like illness (ILI) and acute respiratory illnesses (ARI) outbreaks. This study aimed to elucidate the molecular characteristics of HAdV implicated during ILI outbreaks in Suzhou City, Jiangsu Province in 2024.
Throat swab samples were gathered from settings with ILI outbreaks in Suzhou between March 2024 and January 2025. These samples were analyzed using rapid multi-pathogen detection and real-time PCR. HAdV-positive samples were inoculated into human epidermoid larynx carcinoma cell line (Hep2) for HAdV isolation, followed by whole-genome sequencing (WGS) using the MiSeq platform. Maximum likelihood (ML) phylogenetic trees for the whole genome, hexon, penton base and fiber genes were constructed using IQ-TREE v2.3.6 software. Amino acid variation analysis was performed with BioEdit 7.7.1 software, while recombination detection and visualization were conducted using Recombination Detection Program version 4.101 (RDP4) and SimPlot 3.5.1 software.
Of 488 outbreak samples collected, 53 (10.86%) tested positive for HAdV, making it the second most prevalent respiratory pathogen. These HAdV-related respiratory outbreaks occurred during the spring-summer and autumn-winter transitions, showing no significant regional differences but a slightly higher positive rate in males than in females (13.83% vs. 7.66%, p = 0.028). Twenty-nine HAdV-positive samples were selected for viral isolation and genome sequencing. Phylogenetic analysis revealed that most isolates clustered with recently circulating HAdVB3 strains, while several clustered with HAdVB7 or previously reported HAdVB3/7 recombinant genotypes. Compared with the HAdVB3 reference sequence (OQ518322.1), multiple nonsynonymous amino acid substitutions were identified in antigenic determinant domains (loop 1 and loop 2) of the hexon protein. Besides, four substitution sites were detected in each of the penton base and fiber proteins. Recombination analysis identified seven strains as HAdVB3/7 recombinants, displaying three distinct recombination patterns. Notably, the strain SZTC20241129 carried HAdVB7-derived insertional fragments spanning partial E2B gene region, 52/55 kDa protein, protein IIIa precursor (pIIIa), and the penton base. In contrast, the other recombinant strains (SZZJ20240513, SZTC20241133, SZZJ20240515, SZZJ20240516, SZCS20241240 and SZCS20241242) possessed an HAdVB7-derived genomic backbone along with multiple HAdVB3-derived insertional fragments, encompassing a range of structural and regulatory genes.
HAdV was one of the leading causative agents of ILI outbreaks in Suzhou in 2024, with HAdVB3 being the predominant genotype (22/29, 75.9%). Strikingly, HAdVB3/7 recombinant strains with P7H7F3 and P7H3F3 genetic constituents were also detected in a subset of cases (7/29, 24.1%). The genetic diversity of circulating HAdV continues to expand, driven by the emergence of novel amino acid substitutions and intertypic recombination events. These findings underscore the importance of sustained molecular surveillance to track viral evolution and inform effective public health strategies aimed at reducing the risk of severe clinical outcomes in vulnerable populations.
人腺病毒（HAdV）是一组基因多样的双链DNA病毒，与流感样疾病（ILI）和急性呼吸道疾病（ARI）暴发密切相关。本研究旨在阐明2024年江苏省苏州市ILI暴发期间涉及的HAdV的分子特征。
于2024年3月至2025年1月期间，从苏州市发生ILI暴发的场所采集咽拭子样本。这些样本采用快速多病原体检测和实时荧光定量PCR进行分析。将HAdV阳性样本接种到人表皮样喉癌细胞系（Hep2）中进行HAdV分离，随后使用MiSeq平台进行全基因组测序（WGS）。使用IQ-TREE v2.3.6软件构建全基因组、六邻体、五邻体基座和纤维蛋白基因的最大似然（ML）系统发育树。使用BioEdit 7.7.1软件进行氨基酸变异分析，同时使用重组检测程序4.101版（RDP4）和SimPlot 3.5.1软件进行重组检测和可视化分析。
在采集的488份暴发样本中，53份（10.86%）HAdV检测呈阳性，使其成为第二大最常见的呼吸道病原体。这些与HAdV相关的呼吸道暴发发生在春夏季和秋冬季交替期间，未显示出明显的区域差异，但男性的阳性率略高于女性（13.83%比7.66%，p = 0.028）。选择29份HAdV阳性样本进行病毒分离和基因组测序。系统发育分析显示，大多数分离株与最近流行的HAdVB3株聚集在一起，而有几株与HAdVB7或先前报道的HAdVB3/7重组基因型聚集在一起。与HAdVB3参考序列（OQ518322.1）相比，在六邻体蛋白的抗原决定簇结构域（环1和环2）中鉴定出多个非同义氨基酸替换。此外，在五邻体基座和纤维蛋白中各检测到四个替换位点。重组分析确定七株为HAdVB3/7重组株，呈现三种不同的重组模式。值得注意的是，菌株SZTC20241129携带源自HAdVB7的插入片段，跨越部分E2B基因区域、52/55 kDa蛋白、蛋白IIIa前体（pIIIa）和五邻体基座。相比之下，其他重组株（SZZJ20240513、SZTC20241133、SZZJ20240515、SZZJ20240516、SZCS20241240和SZCS20241242）拥有源自HAdVB7的基因组主干以及多个源自HAdVB3的插入片段，涵盖一系列结构和调控基因。
HAdV是2024年苏州ILI暴发的主要病原体之一，HAdVB3是主要基因型（22/29，75.9%）。令人惊讶的是，在一部分病例（7/29，24.1%）中还检测到具有P7H7F3和P7H3F3基因组成的HAdVB3/7重组株。新的氨基酸替换和型间重组事件的出现推动了流行的HAdV的遗传多样性持续扩大。这些发现强调了持续进行分子监测以追踪病毒进化并为旨在降低脆弱人群严重临床结局风险的有效公共卫生策略提供信息的重要性。
