South Dakota State University (SDSU) researchers are working on an improved vaccine for porcine reproductive and respiratory syndrome (PRRS), still the most economically significant swine disease worldwide.

“We are trying to make the next generation of the PRRS vaccine,” explains research assistant and professor Ying Fang. “It will be a genetically engineered PRRS virus vaccine.”

PRRS is estimated to cost the U.S. swine industry $560 million due to respiratory problems in pigs and reproductive failure in sows.

SDSU researchers, University of Minnesota diagnosticians and vaccine companies collaborated to first isolate the PRRS virus in North America in 1992.

SDSU and the University of Minnesota joined forces again to develop a patented PRRS vaccine that has been licensed to Boehringer Ingelheim Vetmedica, Inc. SDSU has also developed a PRRS virus diagnostic test.

Much of SDSU’s PRRS work now funnels through the school’s Center for Infectious Disease Research & Vaccinology, formed in 2004.

SDSU’s Fang is a molecular biologist who led a U.S. team of researchers to China in December 2007 to study a severe PRRS outbreak.

One aspect of SDSU research is on how the PRRS virus sabotages the animal’s defense systems.

“We want to identify which genes are responsible for shutting down the host’s protective immunity,” she says, adding that the information will help build a better vaccine against the PRRS virus.

One promising technique the SDSU research team is implementing uses “reverse genetics.” In this process, the team clones the virus and uses that clone to manipulate the viral genomes.