IDENTIFICATION, CLONING AND SEQUENCE-ANALYSIS OF THE EQUINE ADENOVIRUS-1 HEXON GENE

Based on sequence homology with human adenovirus 2 (HAdV2), the hexon gene of equine adenovirus 1 (EAdV1) was identified. HindIII restrictio n fragments containing the hexon and other viral genes were cloned int o the plasmids pUC19 and pBlueScript SK(-) and sequenced. The nucleoti de sequence of the hexon gene was completely determined and partial se quence data were obtained for seven other EAdV1 genes. Amino acid (aa) sequence comparison with published adenovirus (AdV) proteins identifi ed the genes for the IIIa, penton, pVII, pVI, 23K proteinase, DNA bind ing and 100K proteins. The eight EAdV1 genes appeared to be in the sam e relative order as homologous genes of other AdV. The EAdV1 hexon pro tein was encoded between the hexon-associated pVI upstream and the 23K proteinase gene downstream and comprised 2742 nucleotides which trans lated into 913 aa. Similar to other members of the genus Mastadenoviru s the EAdV1 hexon yielded two highly conserved genome segments at the N- and C-termini which flanked intermediate variable and hypervariable regions. The majority of the residue differences between EAdV1 and ot her AdV herons occurred in two loops that are known for other AdV to p rotrude from the surface of the nucleocapsid. Amino acid comparisons w ith other AdV herons revealed highest homology with HAdV12 hexon with 72% identical and 83% functionally similar residues, followed by bovin e AdV3 hexon with 71% identities and 82% functional residue conservati on. Phylogenetic analysis suggested that EAdV1 and other AdV do not ha ve an immediate common ancestor.