Natural variants of human adenovirus type 3 provide evidence for relative genome stability across time and geographic space.

Human adenovirus type 3 (HAdV-B3) has an apparently stable genome yet remains a major circulating and problematic respiratory pathogen. Comparisons of the prototype genome to genomes from three current field strains, including two isolated from epidemics, and a laboratory strain, yielded small-scale nucleotide variations across 50 years of time and space (U.S. and China). This is in contrast to the recombination events that have been reported recently for HAdV genomes. Recombinant genomes have been identified in emergent HAdV pathogens and is a pathway for the molecular evolution of types. These two contrasting views of HAdV genome stability have repercussions in the development and use of vaccines for countering HAdV-B3, as well as in the continued effectiveness of vaccines developed against earlier and current circulating types of HAdV.