Detection of Border disease antigen in tissues of affected sheep and in cell cultures by immunofluorescence.

An account is presented of the distribution of fluorescence in cryostat sections of tissues from eight lambs with Border disease (BD). In young lambs fluorescence was observed in almost every organ, indicating a generalised infection with BD virus. Fluorescence was most prominent in the secretory glands of the alimentary and respiratory tracts, the basal cell layers of the epidermis and mucous membranes, and in the medullary rays of the kidneys. Abomasum, pancreas, kidneys, testicles and thyroid were most consistently affected. Although the number of fluorescing tissues decreased with age, viral antigen could still be detected in two sheep of 22 and 52 weeks old. Border disease viral antigen was demonstrated in cell cultures derived from the brain, kidney and testicle of six out of seven lambs despite the presence of neutralising antibody against bovine virus diarrhoea virus in three of them. The presence of the virus in the skin, the vascular walls and the endocrine system is discussed in relation to the aberrant development of fetal hair follicles, periarteritis and growth retardation respectively.