Genomic Analysis Reveals Dominance of Human Adenovirus Genotype B114 Among Circulating Strains Historically Identified as B3.

Human adenovirus (HAdV)-114 (P7H3F3) is a newly identified recombinant genotype, while recent studies suggest that it likely represents a previously circulating HAdV-3 strain. A total of 413 strains previously identified as HAdV-3 from 20 Chinese provinces during 2000-2024, along with 125 GenBank-derived HAdV-3 strains (1988-2023), underwent genotype reconfirmation and genetic evolutionary analysis using the penton base, hexon, and fiber genes. Furthermore, 97 representative strains were selected for whole-genome analysis to determine their genetic recombination patterns. Of the 538 analyzed strains, 537 were identified as HAdV-114 using three genes, with only one 2010 U.S strain classified as HAdV-3. Phylogenetic analysis revealed three HAdV-114 clades (Clades 1-3): Clade 1 (1988-2019) displayed sporadic circulation, Clade 2 (2023-2024) appeared geographically restricted to three Chinese provinces, and Clade 3 (2000-2024) likely represented the globally dominant strain. Genetic evolutionary analyses indicated that, although HAdV-114 originated from recombination between HAdV-7 and HAdV-3, its three Clades diverged from the parental trajectories, with Clades 1 and 3 sharing a common evolutionary origin and Clade 2 forming an independent terminal cluster. Genomic recombination analysis identified two recombination patterns across the three clades. All clades shared a 3' terminal genomic region (nt 18,794-end) derived from HAdV-3, whereas their 5' ends comprised gene fragments recombined from unknown sources and epidemic HAdV-7 strains, with varied breakpoints. HAdV-114, historically identified as HAdV-3, is the predominant genotype associated with HAdV-related respiratory infections. Therefore, enhanced surveillance of recombinant HAdV strains is imperative for effective disease control.