VARIED PREVALENCE OF BORNA-DISEASE VIRUS-INFECTION IN ARABIC, THOROUGHBRED AND THEIR CROSSBRED HORSES IN IRAN

Borna disease virus (BDV) naturally infects horses and sheep and induc es progressive poliomeningoencephalomyelitis. Here, BDV recombinant pr oteins of the first open reading frame (ORF-I; coding for p40 nucleopr otein) and the second ORF-II (coding for p24 polymerase cofactor) were immunoblotted with plasma derived from 72 healthy (28 Arabic, 17 thor oughbred and 27 cross-bred) race horses at Tehran in Iran to detect an ti-BDV antibodies. In addition, their peripheral blood mononuclear cel ls (PBMCs) were also examined for BDV RNA by a nested reverse transcri ptase-polymerase chain reaction (RT-PCR) at ORE-II. The prevalence of BDV antibodies and/or RNA was 41.2% in Arabic, 23.5% in thoroughbred, and 33.3% in cross-bred horses, but only 17.9, 5.9, and 11.1% of them, respectively, showed positive signals for both BDV antibodies and RNA . Especially, cross-bred horses showed a higher prevalence for BDV RNA , which was detected only in females. In addition, significantly highe r prevalence for BDV RNA was observed in Arabic males and thoroughbred females. The BDV prevalence did not increase with aging of the horse. Sequencing at the region of BDV derived from Iranian horses revealed a slight difference from those of Japanese horse- and European horse-d erived BDVs even in the amino acid residues, although those in the thr ee groups of Iranian horses were quite similar. Thus, the varied preva lence of BDV was observed with the horse strain or sex in Iranian hors es, although BDV sequences were very similar among all three groups in Iran compared with those derived from other countries.