Diagnostic evaluation of a real-time RT-PCR assay for routine diagnosis of classical swine fever in wild boar.

The aim of the study was to evaluate a real-time reverse transcription-polymerase chain reaction (RT-PCR) assay for routine diagnosis of classical swine fever (CSF) in wild boar by using 1000 spleen homogenates that were tested previously negative by virus isolation and 26 homogenates from which CSF virus could be isolated. All 26 positive samples in the virus isolation assay also were found to be positive in real-time RT-PCR. Additionally further 10 samples were detected by real-time RT-PCR out of the 1000 negative samples in the virus isolation. With a commercial CSF antigen-ELISA only 14 out of the 36 real-time RT-PCR positive samples could be detected. The sequence analysis of all ten samples that tested positive by real-time RT-PCR and negative by virus isolation revealed CSF virus-specific sequences. Based on the assumption that all samples with a CSF virus-specific sequence or positive in the virus isolation test originated from truly CSF virus-infected wild boar, the following sensitivity values were calculated as antigen-ELISA, 39%; virus isolation, 72% and real-time RT-PCR, 100%. The use of real-time RT-PCR instead of antigen-ELISA and virus isolation as a routine tool for control and eradication of CSF in wild boar populations is recommended.