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Aetiological and immunological aspects of Jembrana disease in Bali cattle

Hartaningsih, Nining (1993) Aetiological and immunological aspects of Jembrana disease in Bali cattle. PhD thesis, Murdoch University.

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Abstract

The clinico-pathological changes in experimentally induced Jembrana disease in Bali cattle (Bos javanicus) were determined as a basis for the differential diagnosis of the disease and increased understanding of the pathogenesis of the disease process. The incubation period varied from 4 to 12 days. The major clinical signs in the experimentally infected cattle were an elevated rectal body temperature persisting for 5 to 12 days, lethargy, anorexia, and enlargement of the superficial lymph nodes. The case fatality rate was 17%. The major haematological changes included a leukopenia characterized by a lymphopenia, eosinopenia and slight neutropenia. There was also a mild thrombocytopenia, anaemia, elevated blood urea levels (especially marked in those animals that died) and a reduced total plasma protein level. The clinical and haematological changes were most marked during the febrile period.

Crossbred Bali (Bos javanicus x Bos indicus) cattle, Java Ongole (Bos indicus) cattle, Friesian (Bos taurus) cattle, and buffaloes (Bubalus bubalis) exhibited clinical changes and lesions consistent with those detected in Bali cattle with Jembrana disease but were markedly less severe than in Bali cattle. The results confirmed previous epidemiological evidence that the disease has a predilection for and exhibits host-specificity for Bali cattle but indicated that other bovine species can be infected.

The aetiological agent exhibited characteristics of viruses in the family Retroviridae. These properties included the size, morphology and morphogenesis of the virions, the density (1.15 g/ml) in sucrose gradients, and the presence of an intravirion reverse transcriptase. The morphology and apparent morphogenesis of the virions most closely resembled viruses in the subfamily Lentivirinae. Further evidence of the relationship of the virus to lentiviruses was the antigenic relationship of an immunodominant 26K protein of the virus to the 26K capsid protein of bovine immunodeficiency virus.

An enzyme-linked immunosorbent assay (ELISA) and an agar gel immunodiffusion (AGID) test are described which detected antibody in Bali cattle (Bos javanicus) against Jembrana disease virus (JDV). The antibody response was delayed and a maximum antibody response was detected 23 to 33 weeks after infection, but persisted until at least 59 weeks after infection. The correlation between Western immunoblotting and ELISA results in individual sera indicated that the ELISA detected antibody primarily to the 26K virion protein; detection of this antibody would indicate previous infection with JDV but would not be directly correlated with the immune status of animals. The inability to detect a significant antibody response until approximately 8 weeks after infection was consistent with the absence of a significant follicular reaction and the scarcity of plasma cells in lymph nodes and spleen during the clinical and early recovery stages of disease.

There was evidence of a reduced antibody response to Pasteurella multocida and Brucella abortus vaccines in JDV-infected Bali cattle. This supported previous pathological studies that have indicated that effected cattle may have suppressed immune function, and anecdotal evidence suggesting an increased prevalence of secondary infections in cattle with Jembrana disease. An attempt to detect suppression of the cell-mediated immune response was unsuccessful.

An antibody response was detected in a majority of JDV infected Madura and Rambon (crossbred Bos javanicus) cattle, although clinical signs of disease were previously detected in only some of these cattle and the clinical signs that occurred were considerably milder than those in Bali cattle.

A serological survey detected antibody to Jembrana disease virus (JDV), the aetiological agent of Jembrana disease in Bali cattle (Bos javanicus), in cattle in 4 islands of Indonesia: Bali, Sumatra (Lampung, Sumatra Barat, Jambi and Riau provinces), Jawa (in the Banyuwangi district of Jawa Timur), and Kalimantan (Kalimantan Selatan and Kalimantan Tengah provinces). Diseases indistinguishable from Jembrana disease have been reported in all areas where antibody was detected, except Iambi, Riau and Kalimantan Tengah but the results indicated that JDV is now also present in these areas. The serological results indicated that there has been limited spread of the disease from endemic areas to neighbouring areas.

Antibodies were also detected in Ongole (Bos indicus) and crossbred Bali (Bos javanicus x Bos indicus) cattle in Lampung Tengah, and buffaloes in Bali. The presence of antibody but the lack of any evidence of disease in these animals was consistent with the experimental evidence that these cattle breeds and buffaloes can be experimentally infected with JDV but develop only a mild or subclinical disease that would be difficult to detect under field conditions.

A series of vaccination experiments were conducted which demonstrated it was possible to induce a protective immune response against Jembrana disease virus (JDV) in Bali cattle (Bos javanicus) by vaccination with whole virus vaccines prepared from plasma and spleen tissues of affected cattle. The results indicated that none of the vaccination procedures used completely prevented the development of clinical signs in animals challenged with 100 50% infectious doses of virus but that the optimal procedures developed did suppress the clinical signs as assessed by a reduction in the duration of the febrile period, a reduction in the duration of leukopenia, reduced severity of the histological lesions detected in the challenged animals, and no mortality. Optimal vaccination results were achieved using virus inactivated with Triton X-100 and emulsified in a mineral oil adjuvant and administered on 3 occasions at monthly intervals. It was considered probable that the use of this vaccination regime in Bali cattle under field conditions could produce a reasonable level of herd immunity.

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
URI: http://researchrepository.murdoch.edu.au/id/eprint/53267
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