Large scale production of a vaccine and diagnostic reagents for Jembrana disease in Indonesia

To enable the production of a commercial recombinant protein vaccine for the control of Jembrana disease in Indonesia, a commercial fermenter was purchased. Methods of utilising this fermenter for producing recombinant proteins for preparation of a Jembrana disease vaccine, on an expanded scale over that we have not been previously able to achieve under laboratory conditions, have been determined. The fermenter has now been shipped to Vaksindo, a commercial vaccine company in Indonesia, and plans have been made to assist them in the technology required to produce the vaccine. Plans for licensing of the vaccine in Indonesia are in place and a memorandum of understanding for the production and supply of vaccine has been agreed to by the DGLS and Vaksindo.

A safety trial of the recombinant protein vaccine in cattle under field conditions in Indonesia has been completed. One hundred cattle were vaccinated with vaccine containing both Capsid and Tat proteins and 100 cattle were given a placebo vaccine. All cattle were monitored over the next 12 months for side effects and antibody response. The vaccine induced minimal side effects, even in pregnant cattle, and induced a long lasting antibody response that persisted for the duration of the trial. This information will be used to assist licensing of the vaccine within Indonesia.

There is evidence that cattle in Indonesia are infected not only with Jembrana disease virus but also with a non-pathogenic but genetically and antigenically related virus that we assume is closely related to bovine immunodeficiency virus (BIV) present in other countries. The possibility exists that prior infection with BIV may inhibit subsequent infection with Jembrana disease virus and that it may be possible to utilise this observation to control Jembrana disease. The R-29 American strain of BIV was inoculated into Bali cattle and it did not induce any clinical disease but virus replication, peaking about 15 days after infection, was detected. In the BIV-infected cattle, Jembrana disease virus infection 42 days later was inhibited. This is an important observation and has application not only as a means of controlling Jembrana disease virus infection but also in understanding the epidemiology and pathogenesis of the disease within Indonesia, especially in areas where both viruses are present in cattle.

This project is involved with a range of issues that are required the control of Jembrana disease in Indonesia, an acute disease syndrome in Bali cattle with a case fatality rate of about 20%, caused by a bovine lentivirus and now endemic in Bali, java, Sumatra and Kalimantan. The issues include the production of a recombinant protein subunit vaccine in Indonesia, the interaction between Jembrana disease virus and another nonpathogenic bovine lentivirus present in Indonesia, and sustainable production of diagnostic reagents.
Transfer of technology to a commercial vaccine company in Indonesia to enable the production of a subunit recombinant vaccine incorporating Capsid and Tat proteins of Jembrana disease virus was achieved. The process for licensing the vaccine by Indonesian regulatory authorities is in progress and it is hoped this will be completed by early 2009. Agreement has been reached between the vaccine company and government regarding the future supply and use of the vaccine in areas of Indonesia where Jembrana disease is endemic.
In Indonesia, Jembrana disease virus occurs concurrently with an an apparently nonpathogenic bovine lentivirus (presumed to be closely related to bovine immunodeficiency virus, BIV), and the interaction between these two viruses in cattle could be significant in the pathogenesis and perhaps control of Jembrana disease in Indonesia. The hypothesis that BIV might provide protection against subsequent Jembrana disease virus infection was therefore investigated. BIV was demonstrated to replicate in Bali cattle with peak virus titres 2-3 weeks post-infection and the lack of pathogenicity of this virus in Bali cattle was confirmed. Subsequent infection of BIV-infected cattle with the pathogenic Jembrana disease virus demonstrated two effects: in some BIV infected cattle, subsequent Jembrana disease virus infection was ameliorated, whereas in other BIV infected cattle there was increased replication of Jembrana disease virus. Further investigation of this interaction between the two viruses in Bali cattle is being conducted.
Original sequence analysis of one strain of Jembrana disease virus was achieved in 1988 but only limited studies of other strains of the virus has been undertaken since then. To further our understanding of the genomics of Jembrana disease virus, sequence analysis of the complete genome of three additional strains of JDV was completed. Results indicate diversity between strains detected in Bali and Kalimantan, suggesting these strains did not have a common origin and may have arisen as a result of separate incursions from the original host (whatever that animal was). Preliminary analysis of the genome of additional strains from Kalimantan suggests there is further diversity in these strains from Kalimantan. The possibility of buffalo as the original host of JDV was suggested by the detection of JDV in buffalo in Bali.
Other investigations, still in progress, include the local production in Indonesia of a recombinant protein antigen suitable for use in Jembrana disease virus serological tests, and the development of a type-specific serological test that will differentiate antibody to the pathogenic Jembrana disease virus and the antigenically and genetically related but nonpathogenic bovine immunodeficiency virus. The current serological tests that are used will not differentiate antibody to the two viruses making serological surveillance results difficult to interpret. The identification of type-specific epitopes by peptide mapping is being investigated to identify unique epitopes in Jembrana disease virus proteins.