Molecular detection and genetic characterization of pestiviruses associated with abortion in domestic small ruminants in Türkiye.

Abortion in small ruminants significantly reduces productivity, with pestiviruses recognized as major viral contributors. Due to their broad host range, sheep can be infected not only by classical pestiviruses, such as bovine viral diarrhea virus (BVDV) and border disease virus, but also by newly identified pestivirus species. This study aimed to molecularly detect and genetically characterize pestiviruses associated with abortion in small ruminants from eastern Türkiye and to evaluate their epidemiological distribution. Samples from 85 sheep and 14 goats were tested for pestivirus RNA using a pan‑pestivirus 5' untranslated region RT‑PCR assay and screened for Schmallenberg virus (SBV). Pestivirus RNA was detected in 13 of 99 animals (13.13%; 95% CI 7.2-21.3%), whereas SBV RNA and viral co-infections were not detected. Sequencing of eight positive samples revealed two distinct species: Pestivirus A (BVDV-1a) and Pestivirus I (Aydin-like pestivirus). Phylogenetic analysis demonstrated that BVDV‑1a sequences were closely related to Turkish cattle strains, supporting cross‑species transmission, while Aydin‑like pestiviruses clustered with local ovine isolates. Overall, the circulation of BVDV‑1a and Aydin‑like pestiviruses highlights their important role in small ruminant reproductive losses and underscores the need for integrated surveillance, including the identification of persistently infected animals, vaccination strategies, and improved biosecurity measures.