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 hemorrh agic enteritis virus (HEV), a type II avian adenovirus, in a 2477-base pair (bp)-EcoRI fragment of the viral DNA by sequence analysis. Ident ification 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 en codes a 448-amino acid polypeptide of molecular weight of 50,843 Da. T he 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) s uggesting that HEV may not use alpha v integrins to gain entry into ho st 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 i ncludes lymphocytes and monocytes. The presence of LDV motif in the pe nton base of HEV implicates the involvement of alpha 4 beta 1 integrin s in the viral internalization into host cells.