Sequence analysis of the fiber genomic region of a porcine adenovirus predicts a novel fiber protein.

The complete nucleotide sequence of the putative fiber protein of a porcine adenovirus isolate, NADC-1, was determined. The coding sequence for the fiber protein was found to be 2112 nucleotides, predicting a 703 amino acid protein with a calculated molecular mass of 76,681 Da. The coding sequence is located between 86 and 92.5 map units. A polyadenylation signal was found 44 bases downstream of the stop codon. Northern hybridization analysis identified a band at 2.4 kb, which likely includes the primary transcript plus a tripartite leader (typically found with adenovirus transcripts) and a polyA(+) tail. The predicted NADC-1 fiber protein was found to have a tail domain comparable in size and sequence to most adenovirus fiber proteins, a comparatively short shaft region, and a head region that was more than twice as large as that of other adenovirus fiber proteins. Each of the three structural domains (tail, shaft, and head) of the predicted NADC-1 fiber protein was found to be most similar to the corresponding domain of a different mammalian adenovirus. The NADC-1 fiber head contained an RGD sequence, a motif that is found in the penton protein of other adenoviruses. Furthermore, the predicted amino acid sequence of the C-terminal half of the NADC-1 fiber head has significant homology to S-lectin proteins, a characteristic not shared with other adenovirus fiber proteins. Thus the predicted amino acid sequence of the NADC-1 fiber head is unique among adenoviruses for which the sequence of the fiber protein is known.