To locate the E4 region on the genome of the HNF-70 prototype strain of the
porcine adenovirus serotype 5 (PAdV-5), 4.5 kb at the extreme right end wa
s sequenced. This area had 11 open reading frames (ORFs) on the left strand
encoding more than 50 amino acids (aa). A Genbank homology search indicate
d that 8 of these ORFs were unique to PAdV-5. ORF5:253 aa, ORF6:245 aa and
ORF11:146 aa showed similarities to known mammalian and avian adenovirus E4
ORFs. The putative E4 promoter sequences were also identified. Two TATA bo
xes, several GC boxes and two typical CCAAT boxes were located within this
region. The presence of several potential poly-adenylation signals and the
number of E4 transcripts detected by Northern blot analysis suggested the p
ossibility of a complex mRNA transcription.