Sequence analysis of Jembrana disease virus strains reveals a genetically stable lentivirus

Jembrana disease virus (JDV) is a lentivirus associated with an acute disease syndrome with a 20% case fatality rate in Bos javanicus (Bali cattle) in Indonesia, occurring after a short incubation period and with no recurrence of the disease after recovery. Partial regions of gag and pol and the entire env were examined for sequence variation in DNA samples from cases of Jembrana disease obtained from Bali, Sumatra and South Kalimantan in Indonesian Borneo. A high level of nucleotide conservation (97-100%) was observed in gag sequences from samples taken in Bali and Sumatra, indicating that the source of JDV in Sumatra was most likely to have originated from Bali. The pol sequences and, unexpectedly, the env sequences from Bali samples were also well conserved with low nucleotide (96-99%) and amino acid substitutions (95-99%). However, the sample from South Kalimantan (JDV(KAL/01)) contained more divergent sequences, particularly in env (88% identity). Phylogenetic analysis revealed that the JDV(KAL/01)env sequences clustered with the sequence from the Pulukan sample (Bali) from 2001. JDV appears to be remarkably stable genetically and has undergone minor genetic changes over a period of nearly 20 years in Bali despite becoming endemic in the cattle population of the island.

TaqMan real-time reverse transcription-PCR and JDVp26 antigen capture enzyme-linked immunosorbent assay to quantify Jembrana disease virus load during the acute phase of in vivo infection

Jembrana disease virus (JDV) is an acutely pathogenic lentivirus that affects Bali cattle in Indonesia. The inability to propagate the virus in vitro has made it difficult to quantitate JDV and determine the kinetics of virus replication during the acute phase of the disease process. We report for the first time two techniques that enable quantification of the virus and the use of these techniques to quantify the virus load during the acute phase of the disease process. A one-step JDV gag [corrected] TaqMan real-time reverse transcription-PCR (RT-PCR) assay was developed for the detection and quantification of JDV RNA in plasma. The limit of detection was 9.8 x 10(2) JDV viral RNA copies over 35 cycles, equivalent to 4.2 x 10(4) JDV genome copies/ml, and a peak virus load of 1.6 x 10(12) during the acute febrile period. An antigen capture enzyme-linked immunosorbent assay (ELISA) was also developed to quantify the levels of JDV capsid (JDVp26) over a linear range of 10 to 200 ng/ml. Viral RNA and JDVp26 levels were correlated in 48 plasma samples obtained from experimentally infected cattle. A significant positive correlation (R = 0.860 and r(2) = 0.740) was observed between the two techniques within the range of their detection limits. The relatively insensitive capture ELISA provides an economical and feasible method for monitoring of virus in the absence of more sensitive techniques.

Natural bovine lentiviral type 1 infection in Holstein dairy cattle. I. Clinical, serological, and pathological observations

Clinical, serological, and pathological abnormalities observed in Holstein cows naturally infected with bovine lentivirus 1 bovine immunodeficiency virus (BIV) and other infections were progressive and most commonly associated with weight loss, lymphoid system deficiency, and behavioral changes. Clinical evidence of meningoencephalitis was dullness, stupor, and occasional head or nose pressing postures. The polymerase chain reactions associated the BIV provirus with the lesions in the central nervous system and lymphoid tissues. Multiple concurrent infections developed in retrovirally infected cows undergoing normal stresses associated with parturition and lactation. A major functional correlate of the lymphoreticular alterations was the development of multiple secondary infections which failed to resolve after appropriate antibacterial therapy. The chronic disease syndrome in dairy cows associated with BIV may be useful as a model system for investigation of the pathogenesis of the nervous system lesions and lymphoid organ changes that occur in humans with lentiviral infection.

Tat protein expression in MDBK cells does not confer susceptibility to bovine immunodeficiency virus

The ability of BIV strain R29 to infect bovine cell lines in the presence or absence of a functional lentiviral Tat protein is described. Jembrana disease virus (JDV) Tat protein was stably expressed in MDBK cells. No viral replication could be detected in this cell line after infection with BIV R29. Transfection of MDBK cells and MDBK Tat expressing cells with BIV R29 proviral DNA established that BIV R29 could not replicate in MDBK cells. Whether viral entry into MDBK cells is also a block to BIV R29 infection of MDBK cells has yet to be established.

Development of disabled, replication-defective gene transfer vectors from the Jembrana disease virus, a new infectious agent of cattle

Jembrana disease virus (JDV) is a newly isolated and characterised bovine lentivirus. It causes an acute disease in Bali cattle (Bos javanicus), which can be readily transmitted to susceptible cattle with 17% mortality. There is as yet no treatment or preventive vaccine. We have developed a gene transfer vector system based on JDV that has three components. The first of the components is a bicistronic transfer vector plasmid that was constructed to contain cis-sequences from the JDV genome, including 5'- and 3'-long terminal repeats (LTRs), 0.4kb of truncated gag and 1.1kb of 3'-env, a multiple cloning site to accommodate the gene(s) of interest for transfer, and an internal ribosome entry site plus the neomycin phosphotransferase (Neo) gene cassette for antibiotic selection. The second element is a packaging plasmid that contains trans-sequences, including gag, pol, vif, tat and rev, but without the env and packaging signals. The third is a plasmid encoding the G glycoprotein of vesicular stomatitis virus (VSV-G) to supply the vector an envelope for pseudotyping. Cotransfection of 293T cells with these three plasmid components produced VSV-G pseudotyped, disabled, replication defective, bicistronic JDV vectors encoding the green fluorescent protein (EGFP) and the Neo resistance selection maker simultaneously with a titre range of (0.4-1.2)x10(6)CFU/ml. Transduction of several replicating primary and transformed cells from cattle, primate and human sources and importantly growth-arrested cells with the JDV vectors showed high efficiency of EGFP gene transfer at 35-75%, which was stable and the expression of EGFP was long term. Furthermore, these JDV vectors were designed to suit the inclusion and expression of genes corresponding to JDV specific proteins, such as gag or env, for the development of vaccines for Jembrana disease. This strategy should also be applicable to other bovine diseases as well. The design and construction of the JDV vector system should facilitate the study of the lentivirology and pathogenesis of the diseases associated with JDV or other bovine virus infections. To our knowledge, this is the first such vector system developed from a cattle virus.

Jembrana disease virus Tat can regulate human immunodeficiency virus (HIV) long terminal repeat-directed gene expression and can substitute for HIV Tat in viral replication

Jembrana disease virus (JDV) is a bovine lentivirus genetically similar to bovine immunodeficiency virus; it causes an acute and sometimes fatal disease in infected animals. This virus carries a very potent Tat that can strongly activate not only its own long terminal repeat (LTR) but also the human immunodeficiency virus (HIV) LTR. In contrast, HIV Tat cannot reciprocally activate the JDV LTR (H. Chen, G. E. Wilcox, G. Kertayadnya, and C. Wood, J. Virol. 73:658-666, 1999). This indicates that in transactivation JDV Tat may utilize a mechanism similar to but not the same as that of the HIV Tat. To further study the similarity of JDV and HIV tat in transactivation, we first tested the responses of a series of HIV LTR mutants to the JDV Tat. Cross-transactivation of HIV LTR by JDV Tat was impaired by mutations that disrupted the HIV type 1 transactivation response element (TAR) RNA stem-loop structure. Our results demonstrated that JDV Tat, like HIV Tat, transactivated the HIV LTR at least partially in a TAR-dependent manner. However, the sequence in the loop region of TAR was not as critical for the function of JDV Tat as it was for HIV Tat. The competitive inhibition of Tat-induced transactivation by the truncated JDV or HIV Tat, which consisted only of the activation domain, suggested that similar cellular factors were involved in both JDV and HIV Tat-induced transactivation. Based on the one-round transfection assay with HIV tat mutant proviruses, the cotransfected JDV tat plasmid can functionally complement the HIV tat defect. To further characterize the effect of JDV Tat on HIV, a stable chimeric HIV carrying the JDV tat gene was generated. This chimeric HIV replicated in a T-cell line, C8166, and in peripheral blood mononuclear cells, which suggested that JDV Tat can functionally substitute for HIV Tat. Further characterization of this chimeric virus will help to elucidate how JDV Tat functions and to explain the differences between HIV and JDV Tat transactivation.

Recombinant Jembrana disease virus proteins as antigens for the detection of antibody to bovine lentiviruses

Jembrana disease virus (JDV) is a recently identified bovine lentivirus causing an acute severe disease syndrome in banteng cattle (Bos javanicus) and a milder disease syndrome in Bos taurus cattle in Indonesia. The virus is closely related genetically to the previously identified bovine lentivirus, bovine immunodeficiency virus (BIV). Recombinant clones were produced which contained the capsid (CA) and transmembrane (TM) subunits of the respective gag and env open reading frames of JDV. The proteins were expressed as fusions to the glutathione-s-transferase (GST) enzyme in Escherichia coli and purification was achieved using affinity chromatography via immobilized reduced glutathione. The soluble recombinant CA and TM antigens of JDV were reacted in western immunoblots with both serum antibodies from JDV-infected Bos javanicus cattle and Bos taurus cattle immunized with BIV. The recombinant CA protein of JDV reacted equally well with both the JDV and BIV antisera. The recombinant TM protein of JDV also reacted with antibody from the JDV infected cattle and with the BIV antisera. The results indicated conservation of immunogenic epitopes of the CA and TM proteins of the two viruses. The production of the recombinant proteins should enable the development of rapid and sensitive serological tests for JDV and BIV, and tools for further study of the immune response to JDV and the differential epidemiology of JDV infections in cattle.

Detection of Jembrana disease virus in spleen, lymph nodes, bone marrow and other tissues by in situ hybridization of paraffin-embedded sections

Jembrana disease virus (JDV) is a lentivirus that causes an acute, severe disease syndrome in infected Bali cattle in Indonesia. An in situ hybridization technique was developed that detected JDV genomic RNA in formalin-fixed paraffin-embedded tissue sections, using a digoxigenin-labelled riboprobe. Large numbers of JDV-infected cells were demonstrated in many tissue sections from experimentally infected animals early in the disease course, which was consistent with the extremely high circulating viraemia previously reported to occur during the febrile phase. The number of infected cells was consistently highest in sections of spleen, followed by many other tissues including lymph nodes, lungs, bone marrow, liver and kidney. Infected cells were also identified in the general circulation and within unusual intravascular lesions in lung sections. The relatively high level of infection found in bone marrow suggested that its involvement may be important in the disease pathogenesis, as it is with other lentiviruses.

Identification of hypervariable and conserved regions in the surface envelope gene in the bovine lentivirus

The surface envelope (SU) gene of nine different isolates of the bovine lentivirus (BIV) were compared for nucleotide and deduced amino acid (aa) sequence diversity. Analyses were done both on isolates derived from the original reference strain, R29, and on field isolates of BIV. Six conserved and six hypervariable regions were identified. Many of the hypervariable regions were located in areas predicted to be on the surface of the SU protein. The SU gene comparison among all isolates showed up to a 50% aa sequence divergence. When a conserved region of the reverse transcriptase gene was compared among eight of the isolates, there was less than 11% aa sequence divergence. When comparing all isolates, the greatest size differences in the SU gene are observed in the 2nd hypervariable region (V2) with up to a 104-aa difference between the largest and smallest variant. R29-106, an infectious molecular clone of the original isolate of BIV, has an 87-bp deletion in V2 as compared to prototype isolate R29-127. All R29-derived isolates sequenced for this study had a SU gene size similar to R29-106. The four field isolates sequenced for this study had SU genes larger than R29-127. R29-derived isolates may not be representative of BIV currently present in United States cattle.

Nucleotide sequence analysis of Jembrana disease virus: a bovine lentivirus associated with an acute disease syndrome

The complete nucleotide sequence of the RNA genome of Jembrana disease virus (JDV), a lentivirus that causes an acute disease syndrome in Bali cattle (Bos javanicus), is reported. In addition to the gag, pol and env genes and flanking long terminal repeats (LTRs) that characterize all retroviruses, a number of accessory genes represented by small multiply spliced ORFs in the central and 3'-terminal regions of the genome, including tat and rev that are typical of lentiviruses, were identified. The genome of JDV was 7732 bp in length, 750 bp smaller than the genome of bovine immunodeficiency virus (BIV) strain BIV127. A striking feature of the genome was the many deletions relative to BIV127, the largest of which were 471 bp from the env gene and 157 bp from the U3 (promoter) region in the LTR. There were also several insertions of up to 33 bp in the JDV genome relative to BIV127 found in the env gene and small ORFs that overlap env. Other significant genomic differences between JDV and BIV127 included changes to cis-acting sequences throughout the genome such as promoter and enhancer sequences in the LTR, the trans-activation response region, splice sites and frameshift sequences; alterations to the gag precursor protein cleavage sites and thus the processed products; loss of the vpw and vpy ORFs; and amino acid changes in all coding regions. The significance of these changes is discussed in relation to the differences in pathogenicity between JDV and BIV.

Genomic sequence analysis identifies Jembrana disease virus as a new bovine lentivirus

Jembrana disease virus, the cause of an acute, severe disease in Bali (Bos javanicus) cattle in Indonesia was recently identified as a retrovirus, and possibly a lentivirus. We have produced sequence data representing 598 bp of the pol gene, amplified by PCR from viral cDNA using broadly reactive universal primers for retroviruses and more specific genus-reactive primers for lentiviruses. When the sequence data were compared with that of known lentiviruses and other bovine retroviruses, the closest alignment was with bovine immunodeficiency-like lentivirus (BIV), showing 74% nucleotide sequence identity. This confirmed that JDV is a lentivirus and that it is distinguishable from BIV. The pathogenesis of Jembrana disease is most unusual for a lentivirus infection and differs markedly from that reported for BIV infection.