Border disease: effect of virus administered intracerebrally to newborn lambs

Concurrent Peste des Petits Ruminants Virus and Pestivirus Infection in Stillborn Twin Lambs

Concurrent infection with peste des petits ruminants virus (PPRV) and pestivirus was diagnosed in stillborn twin lambs. With the flock history, the findings of epidermal syncytial cells and necrotizing bronchitis/bronchiolitis prompted testing for PPRV infection, and PPRV antigen was detected by immunohistochemistry (IHC) in the skin, lungs, kidneys, rumen, and thymus. Macroscopic anomalies that were typical of border disease included scoliosis, brachygnathism, prognathism, arthrogryposis, hydranencephaly, cerebellar hypoplasia, and hairy fleece; pestiviral antigen was detected by IHC in the brain, liver, lungs, and kidneys. Tissues from both lambs were positive by reverse transcriptase-polymerase chain reaction (RT-PCR) for PPRV and pestivirus. To the authors' knowledge, PPR has not been reported previously as a congenital infection or in combination with pestiviral infection.

Border disease in sheep

The current knowledge on border disease in sheep is reviewed. This is a congenital and teratogenic disorder induced by pestivirus. The history, etiology, epidemiology, clinical aspects, and pathologic lesions at postnatal and intrauterine infections (as well as in congenitally affected animals), pathogenesis, immunity, diagnosis, and control and prevention of the syndrome are discussed.

Lymphocyte responses to viral antigens and phytohaemagglutinin in persistently viraemic sheep and lambs experimentally infected with Border disease virus

Lymphocytes obtained from lambs 5 to 21 days after experimental infection with Border disease virus (BDV) showed significant blastogenic responses to live or inactivated BDV. Live virus stimulated significantly higher lymphocyte transformation (LT) responses than inactivated virus. Lymphocytes obtained from uninfected control and persistently infected lambs had no significant response to live or inactivated antigen. Lymphocyte responses to phytohaemagglutinin were significantly higher in control lambs than in experimentally infected lambs in samples obtained 5 to 10 days post-inoculation.

Experimental pestivirus infections in newborn goat kids

Two experiments were carried out in which 37 healthy newborn goat kids were inoculated with a non-cytopathic ovine (BDV) or a cytopathic bovine pestivirus (BVDV) by intramuscular or intracerebral injection. No kids showed signs of disease or gross lesions which could be attributed to these viruses, but inoculated kids had lower mean growth rates than the controls. Significant histological changes in the CNS of 14 kids were restricted largely to the white matter and consisted mainly of hypercellular foci comprising microglial/histiocytic cells and mild perivascular infiltration by mononuclear cells. Varying degrees of infiltration of the myocardium by lymphocytes and plasma cells were observed. All kids remained negative for neutralizing antibodies against pestivirus until 2 to 3 weeks after infection. Titres increased during the following weeks. Pestiviruses were recovered from kids necropsied 10 days after inoculation, but not from any kids killed 20 days after inoculation or later. Non-cytopathic virus was isolated from various tissues of four kids that had received BDV and three kids that had been given BVDV. Cytopathic viruses were not recovered from any kids. Mean white blood cell counts in all kids were within the normal range at 4 and 8 weeks after inoculation. The lymphocyte response to stimulation by phytohaemagglutinin was significantly increased on both sampling occasions in the BDV-inoculated kids, while in the BVDV-inoculated animals, a similar increase was seen only at 8 weeks.