Diagnosis of border disease by direct immunofluorescence

Cryostat sections of lambs with Border disease (BD) were stained with the direct fluorescent antibody technique and examined by fluorescent microscopy. In young lambs fluorescence was observed in almost every organ, demonstrating a generalised infection with BD-virus. Although the number of fluorescing tissues decreased with age, fluorescence was still present in a lamb examined at 22 weeks of age. BD-virus was isolated in tissue culture from six out of seven lambs and was shown to persist for as long as five months.