Replacement of Animal Model for Propagation of Classical Swine Fever Challenge Virus by Adaption in the PK-15 Cell Line

Classical swine fever (CSF) challenge virus has been adapted in PK-15 cell line from infected splenic suspension of the challenge virus maintained hitherto by pig to pig passages. Confirmation of viral presence was done by reverse transcription-polymerase chain reaction (RT-PCR) and Fluorescent Antibody Technique (FAT). A reasonably good titre of 106.5 TCID50/ml was obtained at 6th passage level. The cell culture adapted challenge virus at a dose of 105.0 TCID50 produced CSF symptoms in pigs from 2 nd days post infection (dpi) onwards and succumbed to the infection between 11-12 dpi. Cell culture adapted CSF challenge virus offers advantage to inoculate exact virus particles over the traditional tissue suspension (20% w/v) in potency testing. Adapted challenge virus will replace the use of pigs for propagation of challenge virus; hence follows 4 R’s (replacement, reduction, refinement and rehabilitation) principle. This challenge virus can be attenuated by further serial passages and can be used to develop indigenous live attenuated cell culture based vaccine.