BRAIN MALFORMATIONS IN OVINE FETUSES ASSOCIATED WITH THE CYTOPATHOGENIC BIOTYPE OF BOVINE VIRAL-DIARRHEA VIRUS

A total of six ewes were intravenously inoculated at between 65 and 68 days of gestation with the Indiana strain of bovine viral diarrhoea v irus (BVDV), containing both non-cytopathogenic (ncp) and cytopathogen ic (cp) biotypes. Eight transplacentally infected fetuses were sequent ially removed from the infected ewes and were found to have inflammato ry lesions and malformations of the brain. BVDV RNA was isolated from formalin-fixed, paraffin-embedded brain tissue sections and detected b y nested polymerase chain reaction after reverse transcription. The tw o biotypes of BVDV were distinguished by the fact that a sequence inse rtion in the RNA of the cp biotype of the inoculum results in larger a mplicons. Only RNA from cp BVDV was detected in three of the brains re moved up to 14 days post-inoculation (p.i.), and no BVDV RNA was detec ted after more than 14 days p.i. These findings suggest that, in criti cal phases of development, cp BVDV may transplacentally infect the ovi ne fetal brain and cause malformations.