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November 30, Last modified: January 31, This is version 12 of the entry and version 1 of the sequence.

National Institutes of Health. Do not show this banner again. Four distinct tokens exist: It lists the nodes as they appear top-down in the taxonomic tree, with the more general grouping listed first. Homo sapiens Human [TaxID: Integrated resource of protein families, domains and functional sites More Pfam protein domain database More Superfamily database of structural and functional annotation More Select the link destinations: EMBL nucleotide sequence database More Database of comparative protein structure models More ProtoNet; Automatic hierarchical classification of proteins More The DNA sequences were therefore translated into protein sequences, which were used for further phylogenetic analysis.

Bootstrap values were calculated from replicates. In addition to the hexon, fiber and penton sequences of all adenovirus serotypes available in public databases were used for phylogenetic analysis. The sequences determined in the course of the present study are registered under the following GenBank accession numbers: An alignment of hexon proteins of the 34 AdV serotypes sequenced in our laboratory was performed together with the 17 already known hexon DNA sequences, which had been derived from public databases and translated into putative protein sequences.

Two nonhuman hexon proteins derived from bovine and equine adenoviruses were included in the comparative analysis. The sequence divergence across the complete hexon protein among all 51 human adenovirus serotypes ranged from 0. The newly sequenced AdV serotypes confirmed the general pattern of conserved and highly variable regions in the hexon protein described previously 5 , Based on the sequence analysis, we divided the protein into four conserved C1 to C4 and three variable regions V1 to V3. Taking the hexon of serotype 2 C02 as a positional reference, C1 extends from 1 to aa, C2 from to aa, C3 from to aa, and C4 from to aa.

The variable regions, which are interspersed between the constant regions Fig. When using the C02 sequence as a reference, V1 extends from to aa, V2 from to aa, and V3 from to aa.

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This classification differs somewhat from earlier descriptions of variable hexon regions 5 , 23 but fits in with the three-dimensional structure of the hexon gene, according to which the variable regions V1 and V2, as described herein, are located on loop 1, while the variable region V3 resides on loop 2 of the hexon protein. Hence, the variable regions V1 to V3 are located on outwards-oriented positions of the hexon protein on the virus surface and represent potential epitopes for recognition by neutralizing antibodies Schematic illustration of the hexon protein structure.

Variable regions V1 to V3 are located in the loops designated 1 and 2 and are therefore outwardly oriented on the surface of the virus particle. The indicated amino acid positions are based on the reference serotype C In the conserved regions C1 to C4, which extend over aa of the hexon protein, the highest interspecies similarity observed was between AdV serotypes of the species B, E, and D average divergence ranged from 6.

Species A and F also appear to be closely related divergence, 7. The divergence between species C and all others is about half of that between human and bovine or equine adenoviruses, indicating a rather early phylogenetic differentiation of the human adenovirus species.


Natural Adenovirus Type 5 hexon protein (ab) | Abcam

The lowest average divergence was observed between serotypes of species D range, 0. The greatest divergence was detected between the serotypes of species B, which ranged from 0. By contrast, the variable regions V1 to V3 showed a relatively high average divergence even within individual species. The most pronounced divergence was present between the two serotypes of species F The divergence of protein sequences within the variable regions between AdV serotypes of different species was in the range of The highest value is close to the divergence between human and bovine or equine adenoviruses.

A significant part of the divergence is attributable to insertions or deletions, which account for Based on the protein sequence data, phylogenetic trees were constructed. Neighbor-joining NJ trees were calculated separately for the conserved regions length of alignment, aa; Fig. For the tree based on the conserved regions, the bovine and equine hexon sequences were used as outgroups to root the tree. For the variable regions, alignment of animal and human adenovirus sequences was not feasible, and midpoint rooting was therefore employed.

Phylogenetic analysis of AdV hexon. Bootstrap values are given for the basal nodes of each species A to F. The positions of the framed serotypes D51 and B50 in both trees and B16 in tree b are not in accordance with their previous species assignments. With the exception of serotypes B50 and D51, which will be addressed separately in the following section, the clades correspond to the six species A to F.

Species E, which is represented by a single serotype E04 , is closer to species B than to D. The D clade which includes B50 forms a homogeneous cluster of closely related sequences.

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Due to the high sequence similarity, the number of phylogenetically informative positions is limited and the relationships within the clade are thus not resolved. However, since the conserved sections of the hexon protein are apparently under strong functional constraints, most nucleotide changes are synonymous substitutions and the variable sites therefore have reached saturation for the deeper splits already.

Although there is no resolution of the basal branching points within the D clade, some groupings are consistently found both in NJ and MP analyses. NJ, 99; MP, 99; p-distance, 2. The branching pattern within the D clade is characterized by short distances between nodes compared to the lengths of the terminal branches. This finding suggests that over a rather short period of time a radiation burst has occurred within species D giving rise to the high number of serotypes observed today. Although the alignment was problematic in some sections and the sequence is rather short, the general structure of the phylogenetic tree obtained from the variable regions Fig.

The clades D, B, and C are well supported. Clade A is only marginally supported and clade F is disrupted, but the bootstrap values for this rearrangement are low.

Natural Adenovirus Type 5 hexon protein (ab123995)

The relationships within clades are not in accordance with those in Fig. Interestingly, B16 clusters with E Fiber gene sequences of 25 different serotypes and penton gene sequences of 13 serotypes derived from public databases were translated into putative protein sequences, and phylogenetic trees NJ and MP were calculated data not shown.

Both data sets included representatives of all six species. Unfortunately, no penton sequences are available for serotypes B50 and D51, where the hexon data indicate affiliation to a different species. With the penton sequences, a reasonable alignment of the 13 proteins was obtained over the entire length aa.

Sequence divergence varied from 1. In contrast to the penton proteins, the 25 fiber proteins differed considerably in length aa for B3, aa for C2 as well as in sequence. Even then, only partial sequences could be used for the calculation of phylogenetic trees. The results corroborate the species assignment of the various serotypes.

The fiber protein of serotype B16 partial sequence of aa available only , which was not unequivocally assigned in the hexon trees see also the discussion below , clearly belongs to species B. The results also show that the hexon protein is more appropriate for phylogenetic analyses. Among the three AdV protein sequences compared, conserved sections of the hexon protein permitting unequivocal alignment extend over aa. This sequence is considerably longer than that in the penton or fiber protein and therefore provides a much higher number of phylogenetically informative sites.


Moreover, sequence similarity within the hexon is higher than in the other two proteins, where the deeper nodes in the trees are more affected by saturation of amino acid replacements. Finally, because of the pronounced length variation among AdV species with available sequence information, the fiber proteins cannot be employed for phylogenetic analyses.


The phylogenetic analysis presented has confirmed earlier classifications of most adenovirus serotypes. Two AdV serotypes, B50 and D51, however, clustered with serotypes of species different from the original assignment: These results are indicated in Fig. To exclude the possibility of erroneous numbering of the two serotypes, either in the laboratory of origin or in our center, we have obtained the AdV serotypes B50 and D51 from two independent sources and sequenced the variable regions for close comparison.

The appropriate DNA alignments revealed that no inadvertent exchange of serotype numbers had occurred. Careful comparison of the DNA sequences showed, however, that the reference strains obtained from a center in The Netherlands and the second set provided to us by a center in Germany see Materials and Methods differed by a small number of mutations data not shown. These observations indicate that the sets of reference strains of the two serotypes represent different substrains of the respective viruses and suggest that our assignment of the serotypes 50 and 51 to other AdV species was not attributable to an error in numbering.

Assignment of the sequences B50, D51, and B16 according to similarities at the protein level. The complete hexon gene sequence information and the phylogenetic trees revealed that, when the conserved regions were analyzed, AdV serotype 16, a representative of species B 24 , clustered together with other B serotypes Fig. On the basis of the variable regions, however, it was found to cluster with serotype E04, the only representative of species E Fig.

A high similarity between the serotypes B16 and E04 within loops 1 and 2 has been described previously A protein alignment of hexon sequences derived from all B serotypes including serotype 51 and excluding serotype 50 together with the E serotype E04 shows high similarity between B16 and the other B serotypes inside the C1 region.

At the C-terminal end of C1, exactly at amino acid position displaying a cysteine residue, there is a shift in homology. At the N-terminal end of C4, at position displaying a serine residue, the similarity to serotype E04 is over and the downstream sequences again display high similarity to other serotypes of species B. This observation suggests that serotype B16 could be a recombinant adenovirus, composed of sequences derived from species B and E, with breakpoints located close to positions and Based on the DNA alignment of this set of serotypes data not shown , we were able to determine the breakpoint locations more precisely: To verify this notion and to investigate whether this recombination is found in other representatives of serotype B16, we sequenced the regions adjacent to the putative breakpoints in a reference strain of serotype B16 obtained from a second independent source see Materials and Methods.

Sequence analysis revealed the same positions of the putative breakpoints encompassing a fragment with characteristics of variable regions of species E, confined by the constant regions C1 and C4, displaying high homology to other serotypes of species B data not shown. Nevertheless, a few point mutations including two missense mutations and one silent mutation were observed in the C4 region, indicating that a reference substrain of serotype B16 different from the one described earlier has been investigated.

The presence of the putative breakpoints at identical positions within the hexon sequence confirmed, however, that AdV serotype B16 may represent a recombinant virus between serotypes of species B and E. The variable domains representing approximately one-fifth of the hexon protein length show very limited similarity among AdV serotypes belonging to the same or to different species.

Despite this fact, the phylogenetic trees Fig. This implies the existence of species-specific domains within the variable regions. A good candidate for such a domain is a short stretch of 5 to 9 amino acids in region V1 positions to in the reference sequence AdV C In addition, several motifs can be identified which are located in the variable regions of only one species. The most prominent feature of serotypes from species C is the greater length of the hexon protein sequence by 13 or more amino acid residues compared to all other AdV species.

This difference is mainly due to a variable stretch of up to 16 acidic glutamate and aspartate residues at the beginning of the V1 region. The comparative sequence analysis performed in this study provides information on the complete hexon protein in the entire spectrum of human adenoviruses. To date, complete hexon gene coding sequences have been available only for a small number of AdV serotypes 5 , 7 , Partial hexon gene sequences of the conserved region of some AdV serotypes were published recently Previous studies on the hexon gene, based on the limited sequence information available, divided the hexon protein into eight conserved domains and seven hypervariable regions HVRs 5 , Based on our hexon gene sequence analysis and the alignment of all 51 human serotypes, we propose a different designation of variable and conserved regions for practical reasons.

The conserved regions C1 to C4 appear to be appropriate for the calculation of phylogenetic relationships among all AdV serotypes and to differentiate between the species A to F. The variable regions V1 to V3 , on the other hand, are useful for the characterization of the serotypes within particular species. As these regions correspond quite well to the hexon loops protruding from the capsid surface, they may also contain the specific epitopes that trigger the immune response.

The complete hexon gene sequence data and the results of the comparative analysis have facilitated the development of a highly specific and economic pan-adenovirus molecular detection method 10 patent pending. More accurate characterization of individual adenovirus types has permitted the reclassification of the serotypes 50 and 51, which had originally been assigned to other species, based on their hemagglutination capacity of rat and monkey erythrocytes and the pattern produced after restriction digestion 8.

Sequence analysis of the entire hexon gene revealed that the serotypes 50 and 51 can be assigned to species D and B, respectively, on the basis of our molecular data.

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