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Recombinant proteins as vaccines and diagnostic antigens for the control of Jembrana disease virus infection in Indonesia

Lewis, Joshua Richard (2008) Recombinant proteins as vaccines and diagnostic antigens for the control of Jembrana disease virus infection in Indonesia. PhD thesis, Murdoch University.

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      Abstract

      embrana disease virus (JDV) is a lentivirus associated with an acute disease syndrome of Bali cattle (Bos javanicus) in Indonesia. Control of Jembrana disease currently involves serological monitoring of infection in endemic areas, restriction of movement of cattle from these areas and ring-vaccination around outbreaks of the disease with a tissue-derived inactivated-virus vaccine.
      Earlier investigations at Murdoch University resulted in a vaccine combining a mix of recombinant capsid (CA) and Tat proteins that ameliorated the clinical signs of JDV infection in vaccinated cattle. This thesis reports the development of an alternative novel fused CA and Tat polyprotein antigen emulsified in incomplete Freund’s adjuvant (IFA) as a vaccine. This polyprotein could be produced in a single operation at a lower cost than the mix of the 2 individually produced recombinant proteins. The effect of vaccination with this CA and Tat polyprotein vaccine was compared to vaccination with a mixture of individual CA and Tat proteins in small groups of cattle that were subsequently challenged with virulent JDV. It was found that the fused polyprotein vaccine elicited a greater antibody response against both the CA and Tat antigens than a vaccine containing the mix of individual recombinant proteins. In cattle vaccinated with the fused recombinant polyprotein the viral load and lymphocyte response to infection was similar to that in cattle vaccinated with the mix of individual proteins. When the CA and Tat polyprotein vaccine was administered to cattle under field conditions, the vaccine induced minimal side effects and an antibody response to both CA and Tat proteins that persisted for 12 months.
      A recombinant protein antigen was produced for ELISA and Western immunoblotting assays that enabled serological detection. This antigen provided an alternative to the whole virus antigen that is currently used in Indonesia for these serological assays. The whole virus antigen is prepared from plasma of JDV-infected cattle using a differential centrifugation technique and is difficult to produce in Indonesia. It was found that a recombinant full length CA (p26) protein antigen used in an ELISA provided sensitivity and specificity equivalent to that obtained by Western immunoblotting with the whole virus antigen. This recombinant CA protein antigen is now used in routine serological assays for detection of JDV in Indonesia.

      Publication Type: Thesis (PhD)
      Murdoch Affiliation: School of Veterinary and Biomedical Sciences
      Supervisor: Wilcox, Graham
      URI: http://researchrepository.murdoch.edu.au/id/eprint/1806
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