Diagnosis and molecular epidemiology of the African horse sickness virus by the polymerase chain reaction and restriction patterns.

African horse sickness is a viral disease caused by an orbivirus belonging to the Reoviridae family. This paper describes a polymerase chain reaction (PCR) for amplifying segments 7, which encode for VP 7, a protein common to the 9 known serotypes of this virus. A reverse transcription step is necessary before amplification. No amplified product could be observed in cell cultures infected with other equine viruses. The amplified DNAs were digested to completion by 8 different restriction enzymes. The restriction fragment length polymorphisms allowed the differentiation of the group of serotypes AHSV-1, 3, 6, 8 and the viruses AHSV-2, AHSV-4, AHSV-5, AHSV-7 and AHSV-9. Differences could also be described between vaccinal strains of the same serotype produced in cell cultures or in brains of suckling mice.