#04-112

Complete

Date Full Report Received

10/21/2005

Date Abstract Report Received

10/21/2005

Investigation

Institution:
Primary Investigator:

We started this project with the conviction that the use of vaccines will always be a cost-efficient method and the preferred approach to control PRRSV infections , provided the efficacy and safety concerns of the current vaccines are contemplated and corrected by the development of better attenuated vaccines. The capacity of PRRSv to infect cells and pigs and to cause serious pathologic alterations is called virulence. This virulence is caused by the different genes and its proteins composing the PRRSV. Our technical approach to the improvement of PRRS live vaccines is based on the notion that mapping, one-by-one, the virulence genes in PRRSV should provide essential information for the development of a differential PRRSV vaccine of unprecedented safety and efficacy The main expected outcome of this research is the development of PRRS viruses with deletions or mutations in virulence/host-range/cell-tropism genes as live attenuated/marker vaccine strains. Rational engineering of new live-attenuated PRRSV marker vaccines requires knowledge of the genetic basis of viral virulence and host range and identification of nonessential regions of the viral genome. Before starting this project , little was known regarding non-essential genomic regions of PRRSV or of any other arterivirus. During this one year , the first in this multi-year project, we have identified important genes that seem to be related to virulence as well as important small fragments of the PRRSv proteins that can be used, upon further testing, to prepare diffferential sero-tests that would allow these vaccines to be used as marker vaccines. The best example of this type of product is the successful case with PRV. Our PRRSV work continues through 2006 thanks to the renewal of support by NPB.