Jembrana disease virus: host responses, viral dynamics and disease control.

Jembrana disease virus (JDV) is the most recently discovered member of the lentivirus family and causes an acute clinical disease in Bali cattle with a fatality rate of approximately 15%. It is genetically related to bovine immunodeficiency virus (BIV) to the extent that infections cannot yet be differentially diagnosed using serological assays due to cross-reacting epitopes. Despite their close genetic relationship the pathogenesis of JDV infection in Bali cattle is very different to that of BIV in cattle and is unusual for a member of this virus family. The dynamics of JDV replication and clearance during the acute stage of Jembrana disease, the viral tropism, molecular analysis of the viral genome and mRNA transcripts, and the current status of vaccine development and diagnostic assays are all reviewed to provide a greater understanding of the factors that make JDV such an unusual lentivirus.

Analysis of Jembrana disease virus mRNA transcripts produced during acute infection demonstrates a complex transcription pattern.

Jembrana disease virus (JDV) is an unusual bovine lentivirus that causes an acute disease syndrome with a 20% case fatality rate after a short incubation period in Bos javanicus (Bali cattle) in Indonesia. Analysis of tat mRNA transcription patterns has identified up to six differently spliced transcripts indicating that, in common with other lentiviruses, JDV uses a complex splicing pattern. RT-PCR analysis of mRNA transcripts produced during the acute phase of infection with JDV(TAB/87) revealed at least 12 differently spliced transcripts involving 9 different splice sites. A single unspliced gag/pol transcript, singly spliced vif and tmx specific transcripts and alternatively spliced env, tat and rev transcripts were identified. A 67 nucleotide putative non-coding exon was identified that shared the same splice acceptor (SA) as vif and was incorporated into alternative transcripts of tat, rev and env.

Regulation of microtubule assembly and stability by the transactivator of transcription protein of Jembrana disease virus.

Microtubules are cytoskeletal polymers consisting of tubulin subunits that take part in diverse cell activities. Many viruses hijack cellular motor proteins to move on microtubules toward the cell interior during the entry process and toward the plasma membrane during the egress period. In addition, viruses often remodel microtubules to facilitate the generation of infectious progeny. In this study, we found that the transactivator of transcription protein of Jembrana disease virus (Jtat) bound tubulin and microtubules both in cells and in the purified system. Microtubule co-sedimentation and co-localization assays revealed a robust interaction of Jtat with microtubules. Tubulin turbidity assay further showed that Jtat promoted tubulin polymerization in vitro in a concentration-dependent manner. Moreover, Jtat promoted the partitioning of cellular tubulin toward the polymeric form, increased the level of tubulin acetylation, and significantly enhanced the cold stability of cellular microtubules. In addition, Jtat-mediated disruption of microtubule dynamics induced the release of Bim from microtubules, leading to profound apoptosis. These results not only identify Jtat as an important viral regulator of microtubule dynamics but also indicate that Jtat-induced apoptosis might contribute to Jembrana disease pathogenesis.

Species differences in the reaction of cattle to Jembrana disease virus infection.

Jembrana disease virus (JDV), a recently identified bovine lentivirus, causes an acute and severe disease in Bali cattle (Bos javanicus). Clinical Jembrana disease has not been reported in other types of cattle and this has led to the belief that the disease is unique to Bali cattle. This study showed, however, that other types were also susceptible. Infection of Friesian (Bos taurus) and crossbred Bali (Bos javanicus x Bos indicus) cattle induced clinical changes and lesions consistent with those detected in Bali cattle, although they were milder and would consequently have been difficult to detect under field conditions. The inoculated crossbred cattle were viraemic for 3 months and developed an antibody response to the virus that persisted for at least 46 weeks after infection.