Viral metagenomic characterization of HAdV-B-related signals in bronchoalveolar lavage fluid from pediatric and adult clinical cohorts.

Human adenovirus (HAdV) is an important respiratory virus in children, but sequence-level evidence for HAdV-related signals in lower respiratory tract samples remains limited. In this study, we analyzed metagenomic next-generation sequencing data from 189 bronchoalveolar lavage fluid (BALF) libraries from pediatric and adult clinical cohorts, including 30 pediatric and 159 adult patients, together with laboratory environmental controls. MEGAN read-level classification was used to screen for Adenoviridae-related signals. HAdV-related contigs were further reviewed, and a BALF-derived HAdV-B-related representative contig was selected for read recruitment and coverage analysis. Phylogenetic trees were reconstructed using penton base, hexon, and fiber protein sequences. Adenoviridae-classified signals were more apparent in pediatric BALF libraries than in adult BALF libraries or environmental controls. Several pediatric BALF libraries showed broad read coverage across the HAdV-B-related representative contig, whereas adult libraries and environmental controls mainly showed low-coverage-breadth signals. Phylogenetic analysis placed BALF-derived penton base, hexon, and fiber sequences within HAdV-B-related lineages. Twenty-seven capsid protein sequences from 12 pediatric samples had best BLASTp matches to references annotated as HAdV-B3 (n = 23) or HAdV-B7 (n = 4). These findings provide sequence evidence for HAdV-B-related sequence signals in clinically selected pediatric BALF samples and support further investigation using targeted assays and genome sequencing.