Complete genome analysis of a novel E3-partial-deleted human adenovirus type 7 strain isolated in Southern China

Human adenoviruses (HAdVs) are implicated in a wide range of human diseases, including respiratory, ocular, metabolic, renal and gastrointestinal. They are responsible for 5-10% of lower respiratory tract infections in infants and children throughout the world. HAdV-7, a member of the B1 subspecies, causes acute respiratory disease (ARD). This pathogen is identified in epidemics, is highly virulent and is associated with clinical manifestations of considerable severity including residual lung damage and fatal outcomes[1]. Previous reports suggested that HAdV-3 and -5 are very stable across 50 years of time and space [2,3], which is common in DNA viruses. But HAdV in general are known to undergo recombination. Earlier studies demonstrated in vitro recombination. But more and more isolates, which were isolated from adenovirus epidemic, undergo new recombination between adenovirus types, which leaded to new"intermediates" or subtypes[4]. All the evidence supports the hypothesis that genome recombination drives the molecular evolution of HAdV types. In our research, we found a HAdV-7 strain isolated from a child with acute respiratory disease, with a large portion of E3 region deleted. The whole genome was annotated (GenBank: HQ659699). It hints that E3 region is also important in adenovirus recombination and molecular evolution.The virus strain (designated HAdV-7 GZ07) in this study was isolated from nasal aspirates of a child with ARD in southern China in 2007. The Nasal aspirate specimen was inoculated to HEp-2 cells for isolation, which was maintained in minimal essential medium supplemented with 100 IU penicillin ml-1, 100 μg streptomycin ml-1 and 2% (v/v) fetal bovine serum. The cells were observed for 1-2 weeks for CPE, and the supernatant was identified by a neutralization assay with type-specific reference antisera raised in rabbits by conventional procedures. Type-specific primers designed to the hypervariable regions (HVRs) of the HAdV hexon were also utilize