A naturally occurring human adenovirus type 7 variant with a 1743 bp deletion in the E3 cassette.

Human adenovirus type 7 (HAdV-7) is an important cause of acute respiratory disease (ARD). Different genomic variants of HAdV-7 have been described, designated 7a-7l. In a previous study to investigate risk factors for ARD and wheezing, nasopharyngeal samples were collected from 90 ill children seeking medical attention in Ribeirão Preto, São Paulo, Brazil. HAdVs were identified in 31 samples and were characterized by serum neutralization and genome restriction analysis. Eleven HAdVs were identified as being HAdV-7, five of which were classified as being of genome type 7p (Gomen). Six other HAdV-7 isolates gave new restriction profiles with all enzymes used and were classified as being a new genomic variant, 7m. These isolates were further characterized by sequencing. The hexon and fiber genes of the 7m variant were nearly identical to the prototype, 7p. However, nucleotide sequences from the E3 cassette revealed a 1743 bp deletion affecting the 16.1K, 19K, 20.1K and 20.5K ORFs.