Molecular cloning and sequence analysis of the penton base genes of type II avian adenoviruses

We describe here the identification of the penton base gene of hemorrhagic enteritis virus (HEV), a type II avian adenovirus, in a 2477-base pair (bp)-EcoRI fragment of the viral DNA by sequence analysis. Identification is based on an extensive amino acid homology between the HEV-open reading frame and the penton base of a fowl adenovirus (FAV-10) and various human adenoviruses. The 1344 bp-penton base gene of HEV encodes a 448-amino acid polypeptide of molecular weight of 50,843 Da. The nucleotide sequences of penton base genes of HEV and marble spleen disease virus (MSDV) are identical. The HEV penton base lacks the RGD motif, present in most human adenoviruses (Ad2, Ad3, Ad4, and Ad 12) suggesting that HEV may not use alpha v integrins to gain entry into host cells. Further sequence analysis revealed the presence of a Leu-Asp-Val (LDV) motif in the HEV penton base amino acid sequence similar to most of the human adenoviruses. LDV motif on the fibronectin has been shown to interact with the alpha 4 beta 1 integrins on cells, which includes lymphocytes and monocytes. The presence of LDV motif in the penton base of HEV implicates the involvement of alpha 4 beta 1 integrins in the viral internalization into host cells.