Attenuation of highly pathogenic porcine reproductive and respiratory syndrome virus by inserting an additional transcription unit

Vaccine. 2014 Sep 29;32(43):5740-8. doi: 10.1016/j.vaccine.2014.08.036. Epub 2014 Aug 26.

Abstract

Transcription regulatory sequences (TRSs) play a key role in the synthesis of porcine reproductive and respiratory syndrome virus (PRRSV) subgenomic mRNAs, which resembles similarity-assisted RNA recombination. In this study, genome instability was found when a highly pathogenic PRRSV (HP-PRRSV) strain was inserted by an additional transcription unit in which a foreign gene GFP was expressed from TRS2 while a copy of TRS6 drove ORF2a/b transcription. Structural protein gene-deleted genomes resulted from enhanced RNA recombinations were identified in the recombinant virus rHV-GFP. Moreover, rHV-GFP replicated slower than parental viruses, and caused less cell death in porcine alveolar macrophages. Pigs infected with rHV-GFP survived with no or mild syndromes, whereas all pigs infected with parental viruses died within 12 days. Our data showed that additional transcription unit insertion could confer genome instability and attenuation of HP-PRRSV.

Keywords: Additional transcription unit; Attenuation; Genome instability; HP-PRRSV.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Gene Deletion
  • Genome, Viral*
  • Genomic Instability*
  • Molecular Sequence Annotation
  • Mutagenesis, Insertional*
  • Nucleic Acid Conformation
  • Porcine Reproductive and Respiratory Syndrome / immunology
  • Porcine respiratory and reproductive syndrome virus / genetics*
  • RNA, Viral / genetics
  • Sus scrofa
  • Swine

Substances

  • RNA, Viral