Penton Base Gene Research Articles

Identification and characterization of penton base and pVIII protein of egg drop syndrome virus

The nucleotide sequence and location of the penton base and pVIII genes of the egg drop syndrome (EDS) virus, an avian adenovirus, were determined. The penton base gene is located at 34.8–38.8 map units. The coding sequence has a length of 1359 nt and encodes a polypeptide of 452 amino acids (aa) with a molecular weight of 51 105 Da. The amino acid sequence shows a homology of 57.3 and 55.3% to the structural protein III of human adenovirus serotype 2 (HAd2) and fowl adenovirus serotype 1 (FAV1). The penton base protein lacks the integrin binding motifs RGD (Arg-Gly-Asp) and LDV (Leu-Asp-Val). At 65.1–67.3 map units an open reading frame of 753 nucleotides was identified which encodes the structural protein pVIII. It forms a protein of 250 aa with an expected molecular weigth of 28 501 Da. Possible protease cleavage sites were identified. Amino acid homologies of 30.8 and 27.7% were found to the HAd2 and FAV1 pVIII genes. Remarkably, the overall amino acid identify with ovine adenovirus pVIII is 52%. The start codons of both genes are shifted leftwards compared with the respective structural elements on the HAd2 or FAV1 genomes which indicates a different genomic organization of the EDS virus.

Genomic location and nucleotide sequence of a porcine adenovirus penton base gene.

The putative penton base gene of a porcine adenovirus serotype 3 (PAV3) has been identified, cloned and sequenced. The genomic location of the PAV3 penton base was deduced by probing a Southern blot with a polymerase chain reaction generated product containing the human adenovirus type 2 (HAV2) penton base gene. Sequencing revealed an open reading frame (ORF) of 1527 nucleotides coding for a polypeptide of 509 amino acids. However, cDNA analysis indicated an acceptor splice site one nucleotide upstream of the second ATG in the ORF. This produced an ORF of 1452 nucleotides coding for a polypeptide of 484 amino acids with a calculated molecular weight of 54.5 kDa. Comparison with the HAV2 penton base amino acid sequence revealed the putative PAV3 penton base homologue to be 87 amino acids shorter with an overall amino acid homology of approximately 65%. Comparison with the penton base proteins of other HAV types revealed a region between amino acid positions 283 and 379 with no similarity.

Characterization of the haemorrhagic enteritis virus genome and the sequence of the putative penton base and core protein genes

Haemorrhagic enteritis virus (HEV) is a member of a genetically ill-defined group within the genus Aviadenovirus which causes significant clinical disease in gallinaceous fowl. Using DNA obtained from a low virulence isolate of HEV passed in turkeys, we developed a genomic restriction map and estimated an apparent genomic length of 25.5 kb. No evidence for extensive DNA hybridization was found between the HEV genome and either the hexon or penton base genes of human adenovirus 2 (HAdV-2) and fowl adenovirus 10 (FAdV-10). The HEV penton base gene was identified by PCR using primers based on conserved adenoviral DNA sequences. The penton base gene was expressed in Escherichia coli as a fusion protein and detected by anti-HEV serum in both colony and denaturing gel immunoblots. DNA sequencing revealed a putative penton base ORF with a predicted amino acid sequence showing approximately 39.0%, 53.0% and 44.2% similarity with the penton base of HAdV-2, human adenovirus 40 (HAdV-40) and FAdV-10, respectively. The penton base gene was located at 43.3-48.6 m.u. on the HEV genome and had a remarkably low G+C content (33.8%). DNA sequencing also revealed ORFs for putative core proteins resembling pVII, p-mu and a partial ORF similar to pVI (hexon-associated protein) of HAdV-2 and HAdV-40. The results support the claim that HEV represents a distinct group of viruses within the genus Aviadenovirus.

Genes for fowl adenovirus CELO penton base and core polypeptides.

A 3.5-kilobase DNA fragment of the fowl adenovirus type 1 (CELO), located between map units 31.1 and 39.4 has been determined. The sequence contains the probable CELO equivalents of the IIIa protein, penton base, pVII and pV core protein genes of human adenovirus (HAV). The CELO penton base and major core protein (analog HAV pVII) were found to consist of 514 (56.8 kDa) and 72 amino acids (8.4 kDa), respectively.

Molecular cloning and sequence analysis of the penton base genes of type II avian adenoviruses

We describe here the identification of the penton base gene of hemorrhagic enteritis virus (HEV), a type II avian adenovirus, in a 2477-base pair (bp)-EcoRI fragment of the viral DNA by sequence analysis. Identification is based on an extensive amino acid homology between in HEV-open reading frame and the penton base of a fowl adenovirus (FAV-10) and various human adenoviruses. The 1344 bp-penton base gene of HEV encodes a 448-amino acid polypeptide of molecular weight of 50, 843 Da. The nucleotide sequences of penton base genes of HEV and marble spleen disease virus (MSDV) are identical. The HEV penton base lacks the RGD motif, present in most human adenoviruses (Ad2, Ad3, Ad4, and Ad12) suggesting that HEV may not use αv integrins to gain entry into host cells. Further sequence analysis revealed the presence of a Leu-Asp-Val (LDV) motif in the HEV penton base amino acid sequence similar to most of the human adenoviruses. LDV motif on the fibronectin has been shown to interact with the α4β1 integrins on cells, which includes lymphocytes and monocytes. The presence of LDV motif in the penton base of HEV implicates the involvement of α4β1 integrins in the viral internalization into host cells.

Characterization of the avian adenovirus penton base

A portion of the fowl adenovirus 10 (FAV-10) penton base gene was located within a Sau3A genomic DNA fragment by the combination of a plasmid expression library and colony immunoassays with rabbit anti-FAV-10-sera. The coding portion of the sequence contained in the expression vector was mapped to a 11.6-kb Bg/II fragment and more precisely mapped to the right-hand end of the 11.6-kb fragment at map units 37.7 to 41.3. Nucleotide sequence analysis of the region revealed an open reading frame of 1575 by with translation of the sequence producing a polypeptide of 525 amino acids in length. The polypeptide predicted from the open reading frame would have a molecular weight of 57.4 kDa. Analysis of the amino acid sequence revealed an overall homology of 41.8% with the human adenovirus 2 (HAV-2) penton base. However, a region near the center of the polypeptide (amino acids 219 to 311) showed a significantly greater level of homology to the HAV-2 penton base (71%). Time course experiments using mRNA confirmed that this gene is expressed at late times postinfection. Upon probing genomic DNA from other FAV serotypes the penton base coding region hybridized to all six different serotypes tested, indicating a relatively conserved DNA sequence among a variety of FAVs.