Isolation of bluetongue virus serotype 1 from aborted goat fetuses.

Abortions and stillbirths were noticed in pregnant goats on a farm in the state of Gujarat, India. About 50% of the pregnant goats aborted or gave birth to dead kids. Bluetongue virus (BTV) antibody in the sera of affected goats was detected using a competitive enzyme-linked immunosorbent assay (ELISA). Viral antigen in the blood of these goats and in the aborted fetal spleens was detected using a sandwich ELISA. Two viruses (SKN-9, SKN-10) were isolated in cell culture from aborted fetal spleens and were confirmed as Orbivirus by demonstration of ten bands in RNA polyacrylamide gel electrophoresis and identified as BTV-1 by sequencing of the VP2 gene. Sequence analyses revealed thatthese isolates were very closely related to a BTV-1 (strain SKN-8) isolated from Culicoides vectors captured on the same farm one month after the occurrence of abortion. Isolation of BTV-1 from fetuses is probably evidence of transplacental transmission of the wild-type strain, because attenuated or laboratory-adapted BTV-1 strains have never been used in this region. This may have important implications in the epidemiology of bluetongue, considering the presence of many BTV serotypes in India.