Identification and sequence analysis of the E1 genomic region of a porcine adenovirus

Sequence analysis and deletion of porcine adenovirus serotype 5 E3 region

A 3000 basepair (bp) region corresponding to the E3 region, the flanking pVIII and part of the fiber protein genes, of the two prototype strains (HNF-61 and HNF-70) of porcine adenovirus serotype five (PAdV-5) was sequenced. A potential E3 promoter and poly-A signals were identified. The size of the E3 region was 2039 (strain HNF-61) and 2020 bp (strain HNF-70) the largest E3 so far reported among PAdVs. Three open reading frames (ORF2-4) were identified within the E3 region. Based on the predicted amino acid (aa) sequences ORF2 was similar to other adenovirus E3 ORFs, ORF3 showed some similarity to a bovine adenovirus (BAdV-1) ORF. ORF4 was unique to PAdV-5. E3 mRNA transcripts were detected early in infection by Northern blot analysis. Genomic clones of HNF-70 with a 1505 or 1237 bp deletions in the E3 region were constructed to map non-essential regions. After transfection of the DNA into swine testicle cells, virions were recovered for only the shorter 1237 bp deletion. At least 60% of the E3 region was not essential for virus replication, bringing the theoretical vector capacity of a helper independent PAdV-5 to 2.9 kb.

Gene expression by atypical recombinant ovine adenovirus vectors during abortive infection of human and animal cells in vitro

An bovine adenovirus, which is phylogenetically distinct from the Mastadeno- and Aviadenoviruses, was used to construct recombinants in which reporter genes were expressed from the OAV major late, or human cytomegalovirus promoters. It was demonstrated by transgene expression that OAV could infect bovine nasal turbinate and rabbit kidney cells as well as a range of human cell types, including lung and foreskin fibroblasts as well as liver, prostate, breast, colon, and retinal lines. Some human lines, e.g., 293 and LNCaP were not detectably infected. Infection occurred even though OAV has a fiber protein with a unique cell binding domain and a penton protein that lacks the integrin-binding Arg-Gly-Asp motif which facilitates entry by human adenoviruses. Most cell lines showed little or no ill effect for several days after infection but a prominent cytopathic effect appeared in fibroblasts after 3-4 days. However, no viral DNA synthesis was detected and replication was abortive. Viral promoter activity during infection of nonpermissive cell types was assayed by RT-PCR. Early promoter activity was detectable in some, but not all cell types. In a liver and a colon carcinoma cell line, none of the promoters examined was significantly active, even when a higher multiplicity of infection was used. Major late promoter activity was not detectable in any cell type. The lack of DNA replication and MLP function suggests that a critical transition from early to late gene expression does not occur during abortive infection by OAV.

The role of biotechnologically engineered vaccines and diagnostics in pseudorabies (Aujeszky's disease) eradication strategies

Modern-day biotechnology has an almost unlimited number of possibilities for reducing the impact of hereditary and infectious diseases. To date one of its most visible and rewarding applications for veterinary medicine has been in the genetic engineering of vaccines and diagnostics to assist in the eventual eradication of pseudorabies (PR, Aujeszky's disease). In the following review we summarize some of the most pertinent issues relative to PR eradication and point out the present and potential role of biotechnology in achieving our goal.

Sequence analysis of the fiber genomic region of a porcine adenovirus predicts a novel fiber protein

The complete nucleotide sequence of the putative fiber protein of a porcine adenovirus isolate, NADC-1, was determined. The coding sequence for the fiber protein was found to be 2112 nucleotides, predicting a 703 amino acid protein with a calculated molecular mass of 76,681 Da. The coding sequence is located between 86 and 92.5 map units. A polyadenylation signal was found 44 bases downstream of the stop codon. Northern hybridization analysis identified a band at 2.4 kb, which likely includes the primary transcript plus a tripartite leader (typically found with adenovirus transcripts) and a polyA(+) tail. The predicted NADC-1 fiber protein was found to have a tail domain comparable in size and sequence to most adenovirus fiber proteins, a comparatively short shaft region, and a head region that was more than twice as large as that of other adenovirus fiber proteins. Each of the three structural domains (tail, shaft, and head) of the predicted NADC-1 fiber protein was found to be most similar to the corresponding domain of a different mammalian adenovirus. The NADC-1 fiber head contained an RGD sequence, a motif that is found in the penton protein of other adenoviruses. Furthermore, the predicted amino acid sequence of the C-terminal half of the NADC-1 fiber head has significant homology to S-lectin proteins, a characteristic not shared with other adenovirus fiber proteins. Thus the predicted amino acid sequence of the NADC-1 fiber head is unique among adenoviruses for which the sequence of the fiber protein is known.