Genetic diversity and phylogenetic characteristics of human adenovirus strains 40/41 circulating in Yantai, China, during 2017–2019

Human adenovirus serotypes 40 and 41 (HAdV-F40/41) are among the leading viral causes of pediatric acute gastroenteritis worldwide, yet their genetic diversity and evolutionary dynamics remain poorly characterized in many regions, including China. In this study, we systematically investigated HAdV-F40/41 strains circulating in Yantai, Shandong Province, from 2017 to 2019. Using a combination of real-time PCR, nanopore sequencing, and next-generation sequencing, we elucidated the phylogenetic relationships, recombination events, and structural features of circulating strains. Our results reveal extensive genetic variability and the emergence of recombinant lineages with altered antigenic profiles, underscoring the role of adaptive evolution and potential immune escape. The identification of key mutations and recombination hotspots in hexon and pVII genes provides important molecular markers for surveillance and risk assessment. These findings enhance our understanding of HAdV-F40/41 evolution and highlight the urgent need for continuous genomic monitoring and targeted vaccine development to mitigate the public health burden of adenoviral gastroenteritis.