CLASSICAL SWINE FEVER VIRUS LEADER PROTEINASE N-PRO IS NOT REQUIRED FOR VIRAL REPLICATION IN CELL-CULTURE

The sequence encoding the viral leader proteinase N-pro was replaced b y the murine ubiquitin gene in a full-length cDNA clone of the classic al swine fever virus (CSFV) strain Alfort/187. The recombinant virus v A187-Ubi showed growth characteristics similar to those of the parent vA187-1 virus. At two occasions cells infected with vA187-Ubi exhibite d a cytopathic effect and were found to contain a subgenomic viral RNA . This RNA lacked the same viral genes as the subgenomic RNA which has been found in all cytopathogenic CSFV strains analyzed so far, but it maintained the ubiquitin sequence.