Differentiation of classical swine fever virus from ruminant pestiviruses by reverse transcription and polymerase chain reaction (RT-PCR).

A reverse transcriptase-polymerase chain reaction (RT-PCR) assay was designed to allow the differentiation of pestiviruses by the expected size of the amplified fragments. One oligonucleotide primer, conserved amongst pestiviruses, and two others specific for either classical swine fever virus (CSFV) or bovine viral diarrhea virus (BVDV), were designed from the 5' non-coding region of the genome. CSFV infected cultures (10 strains) amplified a fragment of an expected size of 200 bp; BVDV cultures (23 strains) or border disease virus (BDV) (2 strains) amplified a fragment of an expected size of 260 bp. The specificity of the amplified fragments was confirmed by restriction enzyme analysis. The threshold of sensitivity was 100 TCID50 for CSFV and 1 TCID50 for BVDV. The RT-PCR described here provides a rapid and sensitive diagnostic tool for the detection and differentiation of CSFV from ruminant pestiviruses.