Detection and differentiation of pestivirus antibodies in sheep and suckler cow herds in Southern Germany.

BACKGROUND: Pestiviruses such as bovine viral diarrhea virus (BVDV) or the ovine border disease virus (BDV) are not strictly species-specific and can be transmitted between related animal species. Due to serological cross-reactivity, antibodies against e.g. BDV may interfere with BVDV diagnostics. To assess the impact of non-BVDV pestiviruses on BVDV surveillance during the transition period from virological to serological testing in a region free from BVDV for six years, the presence and type of pestivirus antibodies in sheep and cattle in Southern Germany were investigated.

RESULTS: Pestivirus antibodies were detected in 15.1% of the examined sheep farms by ELISA and identified as BDV-specific by virus neutralization test. No BVDV-specific antibodies were detected in sheep, consistent with the low prevalence of BVDV in cattle in the investigated region. In cattle, 8.1% of farms and 1.7% of animals were tested positive for pestivirus antibodies by ELISA. Most antibodies were differentiated as BVDV-specific and in those cases, all samples originated from animals that were at least 75 months old, with an average age of 183 months. However, BDV-specific antibodies were detected in six cattle farms.

CONCLUSIONS: BDV seems to be currently the predominant pestivirus in sheep in Southern Germany, while interspecies transmission to cattle appears to be rare. Nevertheless, the presence of BDV-specific antibodies in cattle is relevant for serological BVDV surveillance due to serological cross-reactivity, particularly in the context of declining BVDV seroprevalence.