Arch Virol (2002) 147: 429–435 Detection of antibodies to Borna disease virus (BDV) in Turkish horse sera using recombinant p40 Brief Report H. Yilmaz 1 , C. R. Helps 2 , N. Turan 1 , A. Uysal 3 , and D. A. Harbour 2 1 University of Istanbul,Veterinary Faculty, Department of Microbiology, Avcilar, Istanbul, Turkey 2 University of Bristol, Department of ClinicalVeterinary Science, Bristol, U.K. 3 University of Istanbul,Veterinary Faculty, Department of Internal Medicine, Avcilar, Istanbul, Turkey Accepted August 8, 2001 Summary. The nucleoprotein of Borna disease virus (BDV-p40) was produced in a Baculovirus expression system using sf9 cells. The purity and specificity of the recombinant p40 was confirmed by SDS-PAGE and immunoblotting. The recombinant p40 was used in an ELISA to screen horse sera in Turkey. For this, 323 horses from selected cities in the Marmara region of Turkey were examined clinically and serum was collected from each. All horses were clinically healthy except for a few with wounds on the skin. Antibodies to BDV were detected in the sera of 82 (25%) of 323 horse sera. Six sera were selected that had low, medium or high OD values by ELISA and were analysed by Western blotting. All reacted specifically with p40 at a dilution of 1 in 1000. This is the first report of the detection of Borna disease in Turkey and needs further molecular biolog- ical investigations to compare the Turkish strains with those strains detected in Europe. * Borna disease (BD) was first reported in the 18th century as a neurological disease of horses and was later characterised as a transmissible, progressive polioencephalomyelitis (see [13] for review). Borna disease virus (BDV) infec- tion has since been reported in many warm blooded animals such as sheep, cattle, cat, dog, ostriches and people [3–5, 8, 10, 18, 23]. BDV infection has also been produced experimentally in many species [6, 9, 19, 21]. Borna disease virus (BDV) is a novel RNA virus that is the only member of the family Bornaviridae in the order Mononegavirales. The BDV genome has 6 open