An infectious cDNA clone of a highly pathogenic porcine reproductive and respiratory syndrome virus variant associated with porcine high fever syndrome

Since May 2006, a so-called porcine high fever syndrome (PHFS) has spread all over China. The arterivirus porcine reproductive and respiratory syndrome virus (PRRSV) was believed to be the main causative agent, although the involvement of other pathogens was not formally excluded. The genome of a representative Chinese PRRSV strain, named JX143, was sequenced and used to develop infectious cDNA clones, pJX143 and pJX143M, with the latter containing an engineered MluI site that served as a genetic marker. In various virological assays, the rescued viruses, vJX143 and vJX143M, were indistinguishable from their parental virus. Animal experiments showed that these recombinant viruses retained the high pathogenicity and induced the typical clinical symptoms observed during PHFS outbreaks. This is the first report describing infectious cDNA clones of this highly pathogenic PRRSV. Our results unambiguously fulfil Koch's postulates and define highly pathogenic PRRSV as the aetiological agent of PHFS in China.

Published online ahead of print on 11 June 2008 as DOI 10.1099/vir.0.2008/001529-0.

The GenBank/EMBL/DDBJ accession numbers for the sequence of full-length cDNA clone pJX143 and PRRSV JX143 reported in this paper are EF488048 and EU708726.

Supplementary material is available with the online version of this paper.