Identification and complete genome sequencing of human adenovirus type 55 isolated from a patient with acute hemorrhagic conjunctivitis

Objective To determine the genomic characteristics of a subgenus B human adenovirus strain isolated in Shanghai in 2021.

Methods An adenovirus type 55 strain was isolated and identified from a patient with acute hemorrhagic conjunctivitis （AHC）. Complete genome of the strain was obtained using the next-generation sequencing （NGS）. Phylogenetic trees were reconstructed based on the sequences of Hexon， Fiber， Penton and complete genome to genomically characterize this strain.

Results Phylogenetic analysis based on the complete genome classified this strain （MH2021001） into subgenus B， subspecies B2 of HAdV-55. Hexon gene of MH2021001 had close phylogenetic relationship with HAdV-11， while Fiber and Penton genes had close relationship with HAdV-14. The MH2021001 showed high nucleotide identity with currently prevalent HAdV⁃55 strains （>99.90%）. The complete genome had 99.96% nucleotide identity to the 73-GD_CHN_2016 strain isolated in Guangdong. In addition， the amino acid sequence of MH2021001 had several substitutions in regions coding for E1B， L4， E3 and L5.

Conclusion This strain has been classified to HAdV-B55. No recombination event is identified in the complete genome. Due to multiple amino acid substitutions， the biological characteristics of the strain need to be further identified.