Immunological adenovirus variant strains of subgenus D: comparison of the hexon and fiber sequences.

The fiber and hexon genes of the immunological adenovirus (Ad) variant strains Ad9/Hx and Ad15/Hx, belonging to subgenus D, were sequenced and compared to the corresponding sequences of the prototypes Ad9 and Ad15. It was found that the variants possessed a novel and identical hemagglutinin as they could not be distinguished by hemagglutination-inhibition tests. These serological data were now confirmed on DNA and protein level. The analyzed hexon regions of Ad15 and Ad15/Hx, and Ad9 and Ad9/Hx, respectively, were 100% identical on the amino acid level. The comparison between the variant fibers revealed that they possessed an identical fiber, which was distinct from the Ad9 and Ad15 fiber polypeptides. It seems likely that the donor of the novel fiber protein was a so far unidentified subgroup D adenovirus. The fiber polypeptides of Ad9 and the variants revealed the highest homology (73.7%), whereas the variants and the Ad15 fiber had only 64.2% of the amino acids in common. Most of the differences between the adenovirus serotypes were detected in the fiber knob. Seven conserved sequences found for subgenus D fibers could be confirmed for the fibers of the variants. Furthermore, the data presented complement the knowledge on the organization of subgenus D fiber genes.