Molecular characterization and evolutionary analysis of human adenovirus type 55, related to febrile respiratory illness in the South Korean military.

Adenoviruses are non-enveloped, double-stranded deoxyribonucleic acid (DNA) viruses that belong to the family Adenoviridae. Human adenovirus (HAdV)-55 is associated with severe respiratory illnesses that often lead to respiratory failure and death. HAdV-55 caused a febrile respiratory illness (FRI) outbreak at a military base in the Republic of Korea. The Army Forces Capital Hospital provided DNA samples from 79 patients with FRI; among them, we obtained seven whole-genome sequences of HAdV-55 using next-generation sequencing. Phylogenetic analysis of the complete genome and penton base, hexon, and fiber gene sequences demonstrated type-specific genetic clustering among the seven HAdV-55 strains. We also demonstrated protein modeling, molecular phylogeny, and evolution based on whole-genome sequences of seven HAdV-55 isolates characterized using next-generation sequencing and bioinformatics. Additionally, HAdV-55 strains from different countries have contributed to multiple lineages and genetic evolution. Our findings provide important insights into the evolution, molecular phylogeny, protein modeling, and genome sequencing of HAdV-55 isolates. Further studies are needed to better understand the genetic variants of emerging or re-emerging HAdVs.