Jinjin Wang, Ling Jing, Yali Duan, Xiaolei Guan, Yue Cui, Junhong Ai, Yun Zhu, Ran Wang, Xiangpeng Chen, Yuhai Bi, Zhengde Xie
HAdV-7 was an important pathogen of hospitalized children with ARIs in China, and associated with severe diseases and even death. Cluster 2 was the predominant epidemic cluster worldwide. Although the HAdV-7 genome was relatively conserved and stable, novel amino acid mutations have occurred.
OBJECTIVES: Human adenovirus type 7 (HAdV-7) has caused outbreaks of acute respiratory infections (ARIs) among children in multiple countries. This study aimed to investigate the clinical and genetic characteristics of HAdV-7 in hospitalized children with ARIs in China.
METHODS: Respiratory samples were collected from hospitalized children with ARIs at 10 hospitals across Northern and Southern China between 2014 and 2025 for HAdV detection and genotyping. Clinical data of HAdV-7-positive patients were collected for clinical characteristics analysis. The whole genomes of isolated HAdV-7 strains were sequenced for bioinformatics analysis with those selected from GenBank.
RESULTS: Among 250 HAdV-positive samples, 79 (31.60%) were HAdV-7, ranking second only to HAdV-114 (46.80%). Patients primarily presented with fever, cough, and sputum production. Some cases also complicated with gastrointestinal and neurological symptoms, skin rashes, and ocular diseases. Severe pneumonia occurred in 54.43% of patients, with one death. Whole genome sequence phylogenetic analysis revealed that HAdV-7 could be divided into two clusters. Cluster 1, including the prototype strain, had been rarely reported globally since the discovery of HAdV-7. Cluster 2 was the predominant cluster circulating worldwide, including China. Three novel amino acid substitutions were observed in the Loop 1 region of the Hexon protein, which might be associated with the severe disease phenotype and resulted in the emergence of a positive selection site. Recombination analysis identified a recombination event, which occurred as early as 1988. In vitro experiments demonstrated that HAdV-7 had comparable proliferation capacity with other genotypes of the HAdV-B species.
CONCLUSIONS: HAdV-7 was an important pathogen of hospitalized children with ARIs in China, and associated with severe diseases and even death. Cluster 2 was the predominant epidemic cluster worldwide. Although the HAdV-7 genome was relatively conserved and stable, novel amino acid mutations have occurred.