Molecular detection of African horse sickness virus from selected areas in Ethiopia

Equines are vital to global economies and support millions of livelihoods. However, their productivity and welfare are severely hindered by infectious diseases such as African Horse Sickness, which causes major socio-economic losses in Ethiopia. A cross-sectional study was conducted from November 2022 to May 2023 to isolate and detect African horse sickness virus in equines across epidemic areas of Ethiopia. In total, 30 blood samples and 2 tissue representative specimens were aseptically collected from clinically sick and recently dead animals and transported under cold chain to the National Veterinary Institute, Bishoftu. A total of 32 samples were analyzed using conventional Reverse Transcriptase Polymerase Chain Reaction (RT-PCR), targeting the Viral Protein 7 (VP7) gene to amplify segment 7 fragments of all serotypes with serogroup-specific primers. Of these, 7 samples (21.88%) produced 102bp fragments on 2% agarose gel electrophoresis. For serotyping, the 7 PCR-positive samples were further tested by targeting the gene encoding Viral Protein 2 (VP2) with serotype-specific primers, and serotype 9 was identified from tissue samples with a 228bp band. Only tissue samples were cultured on Vero cells, which exhibited cytopathic effects characterized by cell aggregation, rounding, and detachment. In conclusion, African horse sickness caused by serotype 9 severely impacts equines and leads to high mortality in horses. Strategic disease control through vaccination is essential, and further studies are needed to assess outbreak potential and conduct genotypic characterization of the virus in both equines and insect vectors.