Antiviral responses of bluetongue virus-inoculated bovine fetuses and their dams.

Antiviral responses of bovine fetuses to bluetongue virus (BTV) infection were determined. Fetuses inoculated with BTV at 125 days of gestation apparently had cleared all virus by the time of birth; however, the mechanism responsible for virus clearance was not determined. Interferon production and virus clearance were temporally unrelated. Cell-mediated responses to BTV antigens were not detected by the lymphocyte stimulation test using lymphocytes from infected fetuses or cows. Although virus clearance and fetal production of high titers of neutralizing antibody did coincide, it was considered unlikely that antibody alone was responsible for virus clearance. As congenital BTV infection did not lead to specific immunologic tolerance or postnatal persistance of virus, such animals would not be expected to have a major role in the dissemination of BTV.