Clinical variations of border disease in sheep according to the source of the inoculum

Abstract

Non-cytopathogenic pestivirus obtained from lambs with border disease, with or without nervous signs, was inoculated into pregnant ewes at 57 to 65 days of gestation. Live lambs born to inoculated ewes were clinically identical to the lambs from which virus was obtained, ie, either a hairy birth coat with central nervous system disturbance or a hairy birth coat without central nervous system disturbance.

Congenital tremor and hypomyelination associated with bovine viral diarrhoea virus in 23 British cattle herds

“…There is experimental evidence that there are differences between strains of Border disease virus in their ability to induce hypomyelination in sheep fetuses (Plant and others 1983) but the genetic basis of the differences was not investigated. However, in this investigation there were cohort calves with persistent congenital infection but no neurological signs in eight of the herds (Table 1), and the sequence of the virus isolated from the affected calf in herd 23 was identical to those from two clinically unaffected cohort calves.…”

“…The viral sequencing was applied to a non‐coding part of the genome, which is unlikely to reflect potential interactions between the virus and the host’s cell surface membranes and, in the light of the observations of Plant and others (1983), the results of these limited genetic analyses should be interpreted with caution. However, extensive sequencing and comparison of all the structural genes of several virus isolates from affected and cohort calves would be required to exclude potential point mutations that through, for example, modified cell tropism, might cause a particular virus strain to induce the neuropathological changes observed.…”

Virological and Pathological Findings in Sheep Fetuses Following Experimental Infection of Pregnant Ewes with Cytopathogenic‐bovine‐virus Diarrhoea Virus

“…Beside fetal age and breed of sheep, one of the factors influencing the possible outcome of pestivirus infections in transplacentally infected fetuses is the strain of virus. Experimental studies comparing the effects of cp and/or ncp pestiviruses have shown that there are clear differences concerning their pathogenicity for fetuses or newborn lambs, i.e., the incidence of fetal death, hypomyelination, brain alterations or encephalitis, following infection of pregnant ewes (PLANT et al 1983) or lambs UEWETT et al, 1990), respectively. In a previous study (HEWICKER-TRAUTWEIN and TRAUTWEIN, 1994) it was reported that the inoculation of pregnant Merino ewes with unpurified cp BVDV strain Indiana resulted in a high frequency of cavitating and leukoencephalomalacic lesions in fetal brains.…”

“…Further important factors, which may influence the effects of transplacental infections, are the strain and dose of the virus and the breed of the sheep (NETTLETON, 1990). In experimental infections of pregnant ewes at different stages of gestation both noncytopathogenic (ncp) and cytopathogenic (cp) isolates or strains of BDV (FRENCH et al, 1974;VANTSIS et al, 1976; TERPSTRA, 1981;P O~S et al, 1982; BARLOW, 1983; PLANT et al, 1983;N E~L E T O N et al, 1986) or BVDV (WARD, 1971; SNOWDON et a]., 1975; PLANT et al, 1976;PARSONSON et al, 1979;BARLOW et al, 1980;TERLECKI et al, 1980;NETI-LETON et al, 1986; CARLSSON, 1991) have been used to study the virus-induced alterations in the progeny of these animals. In this study, pregnant ewes were inoculated between days 65 and 68 of gestation with the cp BVDV strain Indiana, which resulted in a high frequency of cavitating and leukoencephalomalacic lesions in the brains of the transplacentally infected fetuses (HEWICKER-TRAUTWEIN and TRAUTWEIN, 1994).…”

Pathomorphological and Immunohistological Findings in Progeny of Goats Experimentally Infected with Pestiviruses

“…That results in an immunological reaction with development of the alternative pathology of BD (BARLOW, 1983). Moreover, the outcome of fetal infection also depends on the viral strain and breed of sheep (BARLOW et al, 1979PLANT et al, 1983). It is striking that the six goat kids with malacic foci were virologically negative and had neutralizing antibodies against BVD virus.…”