The induction of a protective immunity against Jembrana disease in cattle by vaccination with inactivated tissue-derived virus antigens.

The ability to induce a protective immunity against Jembrana disease, an acute lentivirus disease of Bali cattle (Bos javanicus) present in Indonesia, was investigated. A protective immune response was induced in cattle by vaccination with virus-containing plasma and spleen tissue derived from acutely affected cattle. The virus was inactivated with Triton X-100 and emulsified in either incomplete Freund's adjuvant or a mineral oil adjuvant (MOA). The vaccination procedure suppressed the duration and severity of the disease but did not completely prevent the development of disease in animals challenged with 100 infectious doses of virus.

The transmission of Jembrana disease, a lentivirus disease of Bos javanicus cattle.

Methods of transmission of Jembrana disease, an acute and severe disease of Bali cattle (Bos javanicus) caused by a recently-identified bovine lentivirus known as Jembrana disease virus, are described. During the acute disease virus can be detected in saliva and milk. There is evidence of direct transmission from acutely affected animals in close contact with susceptible cattle, possibly by virus in these secretions infecting cattle by the conjunctival, intranasal or oral routes, by which it was possible to infect cattle experimentally. During the acute disease the titre of infectious virus in blood is high, about 10(8) 50% cattle infectious units (ID50)/ml, and it is probable that the virus is also transmitted mechanically by haematophagous arthropods. Recovered cattle are also a potential but probably infrequent source of infection; recovered cattle are persistently viraemic but the titre of infectious virus in blood decreases to about 10(1) ID50/ml by 60 days after recovery from the acute disease, and virus cannot be detected in secretions.

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.

Characteristics of a retrovirus associated with Jembrana disease in Bali cattle.

A virus causing Jembrana disease in Bali cattle (Bos javanicus) was demonstrated to have characteristics of a retrovirus. Reverse transcriptase activity was detected in virus purified by sucrose gradient centrifugation. Electron microscopic examination of tissue from the affected cattle indicated that the virus matured by C-type budding through the plasma membrane and into intracytoplasmic vacuoles of cells in lymphoid tissue, with the formation of circular enveloped virus particles ranging in diameter from 96 to 124 nm with an eccentric nucleoid. Western immunoblotting using sera from recovered animals demonstrated virus proteins of M(r) 100K, 45K, 42K, 33K, 26K, 16K and 14K. The 26K protein of Jembrana disease virus cross-reacted in Western blots with the 26K capsid protein of bovine immunodeficiency virus (BIV). The apparent morphogenesis, protein structure and antigenic relationship with BIV suggested the virus was a lentivirus.

Evidence for a viral aetiology of Jembrana disease in Bali cattle.

Jembrana disease is an acute infectious disease of Bali cattle (Bos javanicus) in Indonesia. High titres of the infectious agent are present in plasma during the febrile phase of the disease. The size of the agent determined by membrane filtration was between 50 and 100 nm, indicating it is a virus and not a rickettsia as previously proposed. Spherical virus-like particles of 75 to 130 nm diameter with a smooth membrane and frequently with an eccentric nucleoid were detected by electron microscopy in plasma from infected animals. The virus replicated in mononuclear cell cultures of peripheral blood origin but not in other cell cultures. The virus and the associated disease have characteristics consistent with viruses in the family Retroviridae.

Studies of experimental Jembrana disease in Bali cattle. I. Transmission and persistence of the infectious agent in ruminants and pigs, and resistance of recovered cattle to re-infection.

The agent causing Jembrana disease, an enzootic disease of Bos javanicus (Bali cattle) occurring in Bali, Indonesia, was shown to occur at high titres in the blood of animals during the febrile period of the disease and to persist in cattle for 25 months after clinical recovery. During the febrile period of the disease, most of the infectious agent appeared to be associated with the plasma fraction of whole blood. There was a linear relationship between the number of organisms inoculated into susceptible Bali cattle and the incubation period, which varied from 4.5 to 12 days. Seventeen of 18 animals in which Jembrana disease had been experimentally induced up to 22 months previously did not develop clinical signs when re-challenged with the infectious agent. Ongole cattle (Bos indicus), Friesian cattle (Bos taurus), buffaloes (Bubalus bubalis) and pigs, but not sheep or goats, developed a mild febrile response, but no other overt clinical signs of the disease after inoculation with the Jembrana disease agent. Ongole and Friesian cattle, buffaloes, and sheep developed a persistent infection after inoculation; the infectious agent persisted in blood or spleen for at least 9 months in buffaloes and for shorter periods in the other species.

Studies on experimental Jembrana disease in Bali cattle. II. Clinical signs and haematological changes.

The clinical and haematological changes which occurred in 18 Bali cattle (Bos javanicus) experimentally infected with Jembrana disease are described. The major clinical signs were an elevated rectal body temperature persisting for 7 days (range 5 to 12 days), lethargy, anorexia, enlargement of the superficial lymph nodes, a mild ocular and nasal discharge, diarrhoea with blood in the faeces and pallor of the mucous membranes. Not all of these changes occurred in all affected cattle. The major haematological changes included leucopenia, lymphopenia, eosinopenia and a slight neutropenia, a mild thrombocytopenia, a normocytic normochromic anaemia, elevated blood urea concentrations and reduced total plasma protein. The mortality rate in the experimentally infected cattle was 17 per cent. The similarity of Jembrana disease to malignant catarrhal fever and to diseases of cattle associated with Ehrlichia is discussed.