Molecular characterization of indigenous human adenovirus (HAdV) isolate from healthy infant stool sample and screening of its antibodies in archival serum samples in Türkiye.

Human adenoviruses (HAdV) are significant etiological agents of infections affecting the respiratory, gastrointestinal, urinary and ocular systems, particularly in adults, infants, and immunocompromised individuals. This study presents the molecular identification of a local HAdV strain for the first time from the stool of a healthy infant in Türkiye, isolated in 2003 and stored for two decades in liquid nitrogen. Molecular characterization of this strain was performed, identifying it as HAdV-C6. Phylogenetic analysis revealed high nucleotide identity (97%) with global strains from Russia, China, Japan, and the USA. A serum neutralization test was conducted to determine the current circulation of this strain, indicating a 9.5% seropositivity rate in archival serum samples collected for the West Nile virus surveillance project. This study provides insights into the persistence and molecular epidemiology of HAdV strains circulating in Türkiye, highlighting the need for continuous surveillance and whole-genome sequencing to assess potential recombination events and genetic variations.