Comparison of different diagnostic methods for the detection of the classical swine fever virus (CSFV) in the early infection period

Virus isolation in the PK-15 cell culture, two commercial antigen ELISAs, r everse transcriptional-polymerase chain reaction (RT-PCR), and flow cytomet ry have been evaluated to detect viremic pigs in the early period of classi cal swine fever virus (CSFV) infection. Domestic pigs were experimentally i noculated with the virulent CSFV strain 'Alfort 187' and two field isolates . CSFV isolation and RT-PCR were found to be: the most sensitive methods fo r the detection of highly virulent CSFV in the early period of infection wh ich is characterized by the absence of clinical symptoms. Using antigen ELI SAs and flow cytometry CSFV could be detected in infected animals after the onset of clinical signs. After infection with a less virulent CSFV field i solate originating from wild bo;lr, viremic pigs could be identified by dir ect virus isolation. The reasons for the negative results of the RT-PCR sti ll remain unknown. In conclusion we recommend to modify the procedure (anti gen ELISA) for the detection of clinically healthy domestic pigs in accorda nce with the decision 98/413/EC.