Biochemical studies on bovine adenovirus type 3. III. Cleavage maps of viral DNA by restriction endoncleases EcoRI, BamHI, and HindIII

Nucleotide sequence, genome organization, and transcription map of bovine adenovirus type 3

The complete DNA sequence of bovine adenovirus type 3 is reported here. The size of the genome is 34,446 bp in length with a G+C content of 54%. All the genes of the early and late regions are present in the expected locations of the genome. However, the late-region genes are organized into seven families, instead of five as they are in human adenovirus type 2. The deduced amino acid sequences of open reading frames (ORFs) in the late regions and early region 2 (E2) and for IVa2 show higher degrees of homology, whereas the predicted amino acid sequences of ORFs in the E1, E3, and E4 regions and the pIX, fiber, and 33,000-molecular-weight nonstructural proteins show little or no homology with the corresponding proteins of other adenoviruses. In addition, the penton base protein lacks the integrin binding motif, RGD, but has an LDV motif instead of an MDV motif. Interestingly, as in other animal adenoviruses, the virus-associated RNA genes appear to be absent from their usual location. Sequence analysis of cDNA clones representing the early- and late-region genes identified splice acceptor and splice donor sites, polyadenylation signals and polyadenylation sites, and tripartite leader sequences.

Restriction analysis and homology studies of the bovine adenovirus 7 genome

We located the cleavage sites for restriction endonucleases EcoRI, HindIII, and BamHI on the genome of bovine adenovirus 7. Cross-hybridization at reduced stringency revealed two regions of homology shared by the DNA of human adenovirus 2 and bovine adenoviruses 7 and 3. These regions correspond to the hexon and the IVa2 protein genes of the human adenovirus. Another region of homology shared only by the human adenovirus and bovine adenovirus 7 corresponded to the penton or the polypeptide IIIa genes. These results allowed us to align the restriction map of bovine adenovirus 7 with respect to the other adenoviruses.

Sequence homology between bovine and human adenoviruses

Cross-hybridization has been detected between corresponding regions of the genomes of bovine adenovirus type 3 and human adenovirus type 2. The most conserved region on the viral genomes encodes the hexon polypeptide. The nucleotide sequence of this region in bovine adenovirus type 3 has been determined. Comparison of the predicted amino acid sequences of the bovine adenovirus type 3 and human adenovirus type 2 hexon polypeptides reveals three regions of nonhomology.

DNA structure, and hemagglutination properties of bovine adenovirus type 2 strains which bypass species specificity

Bovine adenovirus type 2 (Ad bos 2) strains were examined which had been isolated during natural outbreaks among calves, and lambs in Hungary [Belák, S., Pálfi, V.: Arch. ges. Virusforsch. 46,366-369 (1974)]. Differences were detected in hemagglutination properties, and in the restriction site maps of the DNA, which seem to be sufficient to group isolates of Ad bos 2 into two subtypes (subspecies). Some of the strains, recovered from cattle including prototype strain No. 19 are suggested to be separated as subtype A. These viruses hemagglutinate bovine red blood cells, and the physical map of the DNA is similar to, or identical with that of the prototype strain. Virus strains tentatively grouped into subtype B are pathogenic for both cattle, and sheep under natural conditions. Members of subtype B hemagglutinate only rat erythrocytes, and characteristic differences may be detected with BamHI, EcoRI, KpnI, and SalI restriction endonucleases in comparison to the physical maps of the DNA of prototype virus. The genome size of all isolates tested was measured to be of Mr 19.5 to 20.0 X 10(6), similar to Ad ovi 1, 4, and Ad bos 4, and 6. All isolates of subtype B characteristics were shown to encapsidate heterogeneous genome populations which could be distinguished from those of subtype A by the presence of specific restriction endonuclease cleavage fragments with molar ratios of less than 1.0.

Oncogenic adenovirus as mutagen for chinese hamster cells in vitro

Oncogenic bovine adenovirus (BAV3) was shown to induce chromosome aberrations and gene mutations to 6-mercaptopurine (6MP) resistance in Chinese hamster cells. BAV3 showed the highest mutagenic effect at the chromosome level 12--24 h postinfection. After 48 h the yield of aberrations dropped to the control level, where it remained after 72 and 96 h. BAV3 showed a highly significant induction of mutations to 6MP resistance 48 h postinfection. The effect of the combined treatment of cells with 5-bromodeoxyuridine (BrdU) and BAV3 on mutagenesis at chromosome and gene levels proved to be synergistic. The mutagenic activity at the gene level of BAV3, along with the earlier established mutagenic effect of SV40, indicates that this property is probably inherent in many DNA-containing oncogenic viruses. The possible mechanisms underlying malignant transformation and mutagenesis are discussed.

Tumorigenic transformation induced by a specific fragment of DNA from herpes simplex virus type 2

Transfection of Syrian hamster embryo cells with limit digests of Bgl II-, Hpa I-, or Bgl II/Hpa I-cleaved DNA from herpes simplex virus type 2 (strain S-1) but not with salmon sperm DNA resulted in the appearance of refractile, morphologically altered cells at a frequency of 10(-5)/0.005 microgram of viral DNA within two to four passages. Transformed lines manifested reduced serum requirement and anchorage-independent growth and were tumorigenic in newborn hamsters. They expressed ICP10, a viral protein immunologically identical to the cervical-tumor-associated AG-4 antigen. Transforming activity was localized in the 16.5 x 10(6)-dalton Bgl II/Hpa I double-digest fragment CDs-1, which exhibited sequence homology to the Bgl II/Hpa I fragment CD of DNA from herpes simplex virus type 2 strain 333, mapping between coordinates 0.43 and 0.58 on the physical map of strain 333 DNA. This fragment, CD333, was also shown to induce neoplastic transformation.

Biochemical studies on bovine adenovirus type 3. IV. Transformation by viral DNA and DNA fragments

By the calcium technique, intact DNA of bovine adenovirus type 3 (BAV3) was found to transform A31 cells, a clone of BALB/3T3. Transforming activity was resistant to RNase and Pronase but sensitive to DNase. The efficiency of transformation was approximately 5 to 10 foci per mug of DNA. Attempts were also made to test for transforming activity of BAV3 DNA fragments prepared with restriction endonucleases EcoRI and HindIII. The activity was found to associate exclusively with the EcoRI D fragment mapped in the region of 3.6 and 19.7 units (molecular weight, 3.9 x 10(6)). No transformation could be obtained with three HindIII fragments, J, E, and B, located at the left-hand end of the BAV3 genome. However, the enzymatic joining of J and E fragments (0 to 11.9 map units) with a ligase restored the transforming activity. These results suggest that all the genetic information of BAV3 required for transformation is located in the region between 3.6 and 11.9 units on the viral genome. Some properties of A31 cells transformed by BAV3 DNA EcoRI D fragment (TrD) and the ligated DNA of HindIII J and E fragments (TrJE), as well as those transformed by whole BAV3 DNA (Tr), were examined. As compared to untransformed A31 cells, all the transformed cell lines tested showed rapid growth, high saturation densities, and anchorage-independent growth. Moreover, they contained BAV3-specific T antigen and induced tumors in adult nude and BALB/c mice. These properties of Tr, TrD, and TrJE lines were similar to those of BAV3-transformed cells.