Date Full Report Received12/22/2008
Date Abstract Report Received12/22/2008
InvestigationInstitution: Virginia Polytechnic Institute and State University
Primary Investigator: Chenming (Mike) Zhang
Co-Investigators: Patrick Halbur, Xiang-Jin Meng M.D., Ph.D.
Funded ByNational Pork Board
The overall objective of this project is to develop edible vaccines to combat the devastating porcine reproductive and respiratory syndrome (PRRS) as an alternative to current MLVs. The goal is to provide pork producers with cheap, effective, and safe vaccines against PRRSV. Corn, as the major feedstock of pigs, was studied to express the immunogenic PRRSV proteins. To expedite the study, we first used maize callus (cultured maize cells) to express the proteins of interest. The expressed protein was identified, and the protein’s immunogenicity was studied in mouse model. Our results indicated that the major immunogenic PRRSV protein can be successfully expressed in maize callus, and the protein interacted with antibodies developed against PRRSV. The mouse experiments, however, produced inconclusive results about the immunogenicity of the protein expressed in maize callus. The main reason is that the protein expression level in maize callus is relatively low and could not be quantified. Thus, we could not determine how much of the target protein was administered to the test animals. The lack of strong antibody response could very well be attributed to the insufficient amount of target protein administered. Nevertheless, our results have shown that maize is able to express recombinant PRRSV proteins. Although more work needs to be done to increase the protein expression level (currently being investigated) and to study the immunogenicity and antigenicity of the recombinant proteins in mice and pigs, maize expressed viral proteins clearly still hold great promise as effective vaccines against the virus. The continuation and success of this project will have a significant impact on our combat against this devastating virus and the swine producers. Not only will new and safer vaccines be produced, but the vaccines will be much cheaper and extremely suitable for mass immunization. Swine producers will be directly benefited from purchasing cheaper and easy-to-be-administered vaccines and from the improved productivity of the swine farm.