AN IMMUNOHISTOCHEMICAL STUDY OF THE DISTRIBUTION OF BORDER DISEASE VIRUS IN PERSISTENTLY INFECTED SHEEP

Three seronegative sheep persistently infected with Border disease vir us and six seropositive, non-viraemic sheep were examined for the cell ular distribution of the agent. These animals originated from a closed flock which had been kept in an isolation facility for 5 years. They were killed and immediately necropsied. There were no gross abnormalit ies other than reduced body weight of the persistently infected sheep. Two samples of each major organ were collected. The first sample was fixed by immersion in formalin and processed for histological examinat ion, which showed no lesions unequivocally attributable to the viral i nfection. The second sample was snap-frozen for immunohistochemical ex amination. This revealed viral antigen in all organs of the persistent ly infected, but in none of the seropositive animals. The infected cel ls included smooth muscle cells of hollow organs and blood vessels, ep ithelial cells of the alimentary tract and urogenital organs, lymphocy tes in lymphoid organs, endocrine cells, neurons and glial cell. (C) 1 995 Academic Press Limited