Border disease: tissue culture studies of the virus in sheep.

A California strain of border disease (BD) virus was isolated from the CNS and spleen of an infected lamb and was propagated without cytopathic effect on 2 tissue culture systems. Viral antigen was detected in the cytoplasm of infected cells by immunofluorescence. The growth curve of this BD virus in primary sheep choroid plexus cells revealed a latent period of 12 hours and peak viral production by 36 hours after inoculation. The growth curve in porcine kidney cells (PK-15) demonstrated a latent period of 8 hours and peak viral production by 54 hours after inoculation. The primary sheep choroid plexus cell tissue culture isolate of BD virus was then used to develop hyperimmune sera in 2 adult sheep. Neutralizing antibody was not detected until 43 days after primary inoculation when a slow antibody increase occurred in both sheep.