#04-121

Complete

Date Full Report Received

02/07/2006

Date Abstract Report Received

02/07/2006

Investigation

Institution:
Primary Investigator:

The focus of our research funded by the National Pork Board was to develop second generation killed PRRS vaccines. The portion of the PRRS virus responsible for stimulating the neutralizing immune response (an antibody response which removes the virus from the body) is concealed from the immune system in numerous strains. Our research used enzymes to attempt to remove the concealing portions (glycans) on or near the neutralizing region (the area in which the neutralizing antibodies would bind the virus). Evaluation of this neutralizing immune response was carried out in test tubes using serum from the pigs and known PRRS virus quantities. The hypothesis for this research was that a killed vaccine composed of virus particles lacking the glycans would develop a stronger neutralizing antibody response and provide protection from disease. An additional PRRS strain naturally lacking glycans in the neutralizing region was added in the last experiment. Observations in our experiments yielded mixed results. A neutralizing response was seen in some pigs; however this neutralizing response was relatively weak and did not provide protection from disease. The positive aspect of these findings is that a neutralizing antibody response can be elicited with a killed vaccine. A limitation in our research was the ability to determine how much of the killed PRRS virus each pig received. The preparation of our vaccines resulted in cell protein from the cells in which the virus was grown, in addition to the viral proteins, being present in the vaccines. When we increased the amount of this total protein within the vaccine we were able to detect an immune response earlier. These results lay the ground work for future studies evaluating immune response and protection from disease utilizing known quantities of PRRS viral protein.