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Genetic studies of Jembrana disease virus

Chadwick, Brad (1995) Genetic studies of Jembrana disease virus. PhD thesis, Murdoch University.

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Abstract

The complete nucleotide sequence of the RNA genome of Jembrana disease virus (JDV) was obtained. The genome was that of a typical lentivirus. In addition to the gag, pol and env genes and flanking long terminal repeats that characterize all retroviruses, a number of accessory genes were identified. These were small, often multiply spliced open reading frames in the central and 3’ terminal regions of the genome and included tat and rev. The sequence data indicated that JDV was closely related to American isolates of bovine immunodeficiency virus (BIV), the only previously identified bovine lentivims. At 7732 bp in length however, the genome of JDV was 750 bp shorter than that of BIV and the smallest lentivirus genome yet reported. A striking feature was the number of deletions relative to BFV, which ranged from single nucleotides up to a major deletion of 471 bp in the env gene. Other potentially important genomic differences between the two viruses were described, such as alterations to the enhancer elements in the viral promoter.

An in situ hybridization technique was developed that was specific for the detection of JDV genomic RNA in formalin-fixed paraffm-embedded tissue sections, using a digoxigenin-labeled riboprobe. This technique detected large numbers of JDV-infected cells in many tissue sections from limited case material derived from experimentally infected animals. The earliest round of viral replication was found to occur predominantly in the spleen, from where it spread rapidly to other tissues including lymph nodes, lungs, bone marrow, liver, kidney, myocardium and elsewhere. Bone marrow was found to be potentially more important in the pathogenesis of JDV infection than has previously been recognized. Infected cells were also identified in the general circulation and within unusual intravascular lesions in lung sections.

A number of assays based on the polymerase chain reaction (PCR) were developed for the purpose of investigating bovine lentiviruses in Indonesia. A specific assay for the detection of JDV was developed based on sequences in the gag gene and used to amplify proviral sequences from paraffin-embedded tissue specimens. The JDV-specific PCR was cross-tested with a previously reported BlV-specific PCR to confirm that both assays were adequately specific to ensure that differentiation between the two viruses was reliable. A third PCR assay was developed, based on sequences in the pol gene found to be conserved by JDV and BIV, in order to detect closely related potentially novel bovine lentiviruses. A fourth assay was described, based on a nested set of six degenerate primers complementary to sequences highly conserved in the pol gene of all lentiviruses, for the purpose of detecting potentially novel lentiviruses in any species.

Item Type: Thesis (PhD)
Murdoch Affiliation: School of Veterinary Studies
Notes: Note to the author: If you would like to make your thesis openly available on Murdoch University Library's Research Repository, please contact: repository@murdoch.edu.au. Thank you.
Supervisor(s): Wilcox, Graham and Coelen, R.
URI: http://researchrepository.murdoch.edu.au/id/eprint/53230
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