Genomic location and nucleotide sequence of a serotype 3 porcine adenovirus hexon gene

The putative hexon gene of a porcine adenovirus serotype 3 (PAV3) has been identified, cloned and the nucleotide sequence determined. The genomic location of the PAV3 hexon gene was determined and an open reading frame (ORF) encoding a polypeptide of 939 amino acids identified. Comparison of the nucleotide sequence of the putative PAV3 hexon gene with the sequence of the HAV2 hexon gene returned an overall identity of approximately 63%. A stop codon 144 nucleotides upstream and a start codon 18 nucleotides downstream of the ORF were identified and comparison with the HAV genome demonstrated that their positions corresponded to the stop site of the pVI gene and start site of the 23K gene, respectively. To confirm the correct start codon of the putative PAV3 hexon gene, the acceptor splice site for the putative PAV3 hexon gene was determined from cDNA and found to be between the two guanines immediately upstream of the first ATG in the ORF. Comparison with the HAV2 hexon protein showed overall identity of approximately 65%, with higher identity in the carboxy-terminus of approaching 76% over 380 amino acids. Multiple alignment of the PAV3 hexon amino acid sequence with other known HAV and animal adenovirus hexon sequences indicated that conservation is generally maintained but that identity is much lower within the loop structures of the protein.