Hemagglutination properties and nucleotide sequence analysis of the fiber gene of adenovirus genome types 11p and 11a.

The fiber has been suggested to serve as the ligand between the adenovirus capsid and the host cell receptor. The two genome types, Ad11p and Ad11a, of adenovirus serotype 11 display different tropisms. The fiber amino acid sequences of the two genome types have been deduced from the 975 nucleotides that encoded a fiber polypeptide of 35,500 Da. The fiber consists of a tail, a shaft, and a knob region. The amino acids 44 to 140 form a typical shaft domain of six 15-residue repetitive motifs. Ten amino acids in the Ad11p fiber shaft were substituted in Ad11a. Five unpolar residues have been replaced by four polar and one unpolar amino acid. In the knob region, a total of 14 amino acid mismatches were noted between Ad11p and Ad11a. The amino acid sequence Asn-Asp-Glu at positions 283 to 285 in Ad11p was changed to Arg-Ala-Asp in Ad11a. The sequence Thr-Leu-Trp-Thr from positions 133 to 136 was conserved in all analyzed human and canine adenoviruses. The polypeptide at positions 235 to 244, Phe-Met-Pro-Ser-Thr-Thr-Ala-Tyr-Pro-Phe, probably contains a subgenus epitope, since it is conserved among subgenus B adenoviruses. Ad11p aggregated rhesus and vervet erythrocytes at 37 degrees, 22 degrees, and at 4 degrees, respectively, whereas Ad11a did not display hemagglutination under the same conditions. The complete fibers of Ad11p and Ad11a share an overall amino acid homology of 92.3%. The homology within the shaft and the knob region was 89.7 and 92.4%, respectively. These variable amino acids should be expected to be responsible for the differences in hemagglutination and tropism examplified by the persistent urinary tract infections caused by Ad11p and the acute respiratory tract infections caused by Ad11a.