Genomic characteristics and phylogenetic analysis of human adenovirus 14 in China during 2010-2016

Human adenovirus (HAdV) is a common pathogen that causes various respiratory illnesses. Human adenovirus type 14 (HAdV-14) emerged in recent decades and has been reported sporadically and unevenly across the globe. In China, the first occurrence of HAdV-14 was reported in 2010, yet its genetic characteristics and transmission patterns remain unclear. This study performed a comprehensive phylogenetic analysis by integrating nine newly sequenced strains with all 67 available complete genome sequences of HAdV-14 strains from GenBank, which were submitted by eight countries where HAdV-14 is endemic. All examined strains were found to belong HAdV-14p1 clade, which was further classified into three major clusters. Notably, all strains identified in China belong to Cluster II and III. This study found that the initial isolates GZ01 and GZ02 from Guangzhou, China, in 2010 belonged to Cluster II, whereas the GZ25 isolate from the same location and year, identified through this study, belonged to Cluster III. Cluster III, which was sporadically epidemic, has formed a transmission circle in China. Despite multiple mutations in key genes between the two clusters, the homology of the Chinese isolates reached as high as 99.7 %. This study revealed that all HAdV-14 strains have highly conserved capsid proteins in China, which exhibit relative genome stability across time and geographic space. This study enhances our understanding of the genetic diversity and genomic characteristics of HAdV-14 and contributes to the prevention and control of HAdV-14 infection in the future.