Molecular characterization of human adenovirus type 8 (HAdV-8), including a novel genome type detected in Japan

Human adenovirus type 8 (HAdV-8) is a common agent of severe epidemic keratoconjunctivitis (EKC). Twenty-six strains were isolated from sporadic cases of EKC in the southern part of Japan between 1998 and 1999 and were identified as HAdV-8 by the neutralization method using type-specific antiserum against HAdV-8. A comparative analysis of different HAdV-8 genome types was performed using various molecular methods. Restriction enzyme analyses of genomic DNA were performed with BamHI, HindIII, PstI, SacI, SalI, and SmaI and identified 25 isolates as HAdV-8E and 1 isolate as HAdV-8J, a novel genome type. The genetic relatedness between HAdV-8J and the other genome types was calculated by pairwise comigrating restriction fragments. The new genome type was most genetically related to HAdV-8E. In a phylogram of both the hexon and fiber, HAdV-8J formed a monophyletic cluster with other genome types of HAdV-8. Although HAdV-8J was identified from a sporadic case of EKC, this strain may cause future outbreaks and thus warrants further monitoring.