Porcine reproductive and respiratory syndrome was recognized in the U.S. in 1987 as a new infectious disease of swine causing late-term reproductive failure and severe pneumonia in neonatal pigs. The etiological agent is PRRS virus (PRRSV). Current attenuated vaccines against PRRSV are not totally effective in prevention of the infection and disease. In addition, there is emerging evidence that the current attenuated vaccines are not 100% safe due to reversion to virulence. A new generation of safe vaccines with a better performance will help in prevention of this disease. Most, if not all, viral vaccines protect via preexistent specific neutralizing antibodies. There is also strong evidence for a protective role of neutralizing antibodies in protection to PRRSV infection. We propose here to characterize neutralizing epitopes (mimotopes) for PRRSV using phage display libraries of peptides. To select the mimotopes we will take advantage of the characteristic features of porcine antibodies and the humoral response of swine to PRRSV infection. The capacity of these mimotopes to compete to neutralizing anti- PRRSV antibodies will be tested in vitro and selected ones will be used to induce a neutralizing antibody response as a proof of principle. ANTICIPATED RESULTS & POTENTIAL COMMERCIAL APPLICATIONS OF RESEARCH Our goal is to characterize specific areas of molecules (epitopes) from Porcine Respiratory and Reproductive Virus that are targets for the induction of neutralizing antibodies. These molecules or molecules resembling conserved epitopes will be used to produce a new generation of a more safe vaccine against PRRSV. Characterization of neutralizing and non-neutralizing epitopes will also allow us to produce a differential ELISA test to distinguish between PRRSV vaccinated and infected pigs that could be used together with the vaccine in control programs.
