Early detection of Classical swine fever virus in blood samples of Pigs in Karnataka

Abstract

Classical swine fever (CSF) is endemic in Karnataka and its outbreaks are reported every year. In the present study, blood was used for early detection of CSF virus (CSFV) in pigs by reverse transcription-polymerase chaini reaction (RT-PCR) and enzyme linked immunosorbent assay (ELISA). A total of 113 blood samples were collected from 12 outbreaks suspected for CSF in nine different districts of Karnataka, of which 20 CSFV were positive by Antigen ELISA, whereas 40 samples were CSFV positive by RT-PCR using primers specific to NS5B genomic region of CSFV. Among 12 suspected outbreaks, 9 were confirmed as that of CSF. Among these, 44 samples were from pigs showing clinical symptoms and 69 samples were from in contact pigs without clinical symptoms. RT-PCR confirmed CSF from all the 30 samples from pigs with clinical symptoms in addition to 10 samples from pigs without clinical symptoms, indicating there by that the assay detected the presence of 449 bp amplicon specific to NS5B region before the appearance of the clinical symptoms. ELISA did not detect the presence of viral antigen in blood samples of in contact pigs without clinical symptoms. Our findings suggested that blood represents the most appropriate sample for early detection of CSFV infection in pigs.