SEQUENCE-ANALYSIS OF EQUINE ADENOVIRUS-2 HEXON AND 23K-PROTEINASE GENES INDICATES A PHYLOGENETIC ORIGIN DISTINCT FROM EQUINE ADENOVIRUS-1

We report the first nucleotide sequence data on equine adenovirus 2 (E AdV2) which corroborate on the molecular level that EAdV2 is distinct from equine adenovirus 1 (EAdV1). Based on sequence homology with Eadv 1 the hexon gene of Eadv2 was identified. HindIII restriction fragment s containing the hexon and eight other viral genes were cloned into th e plasmid pUC19 and the nucleotide sequence of the hexon and the 23K p roteinase genes completely determined. Amino acid (aa) comparison of s equence fragments with published adenovirus (AdV) proteins identified the genes for the E1B/19K, IVa2, DNA polymerase, terminal protein, pVI , DNA binding and 100K proteins, usually with highest similarities to human AdV. The nine EAdV2 genes appeared to be in the same relative or der as homologous genes of other AdV. The EAdV2 hexon was encoded betw een the minor capsid precursor protein pVI upstream and the 23K protei nase gene downstream and comprised 2712 nucleotides which translated i nto 903 aa residues. It was more closely related to the human AdV48 he xon with 71.6% identical and 82.7% functionally similar aa than to the EAdV1 hexon gene with 69.3% aa identity and 80.7% functional similari ty. The deduced aa sequence of the EAdV2 23K proteinase gene was 201 r esidues; it shared 59.7% identical and 75% similar aa residues with th e bovine AdV3 23K proteinase as the closest relative. Phylogenetic ana lysis of the hexon and 23K proteinase genes indicated that EAdV2 does not share an immediate common ancestor with EAdV1 and other AdV. (C) 1 997 Elsevier Science B.V.