Project Summary
A potential role for anti-Id in the induction of a protective immune response against a wide variety of infectious agents has been previously recognized. We will conduct a “proof-of-concept” study focused on testing whether immunization of pigs with Mab2-3H induces neutralizing antibodies against PRRS virus envelope glycoprotein (GP5), as it did in mice. The ability of anti-Id to manipulate the immune response in vivo has been documented in numerous antibody systems including viruses, bacteria, and parasites. Our recent research in mice showed that monoclonal anti-idiotype (Mab2-3H) induced anti-GP5 antibodies that neutralized PRRS virus infection in MARC-145 cells. The current study will focus on testing whether immunization of pigs with Mab2-3H induces neutralizing antibodies against PRRS virus envelope glycoprotein (GP5) as prior work has shown in vitro and in mice. Additionally, Mab2-3H only induces antibodies against PRRS virus GP5. Thus, a pig vaccinated with Mab2-3H would be differentiable from a pig infected with PRRS virus.

Project Objective
To determine whether immunization of pigs with Mab2-3H induces neutralizing antibodies against PRRS virus envelope glycoprotein (GP5). Furthermore, a recombinant Mab2-3H will be produced in a prokaryotic expression system for testing in a field application.

Relevance to NPB PRRS Initiative Research Objectives
This project represents the application of basic research conducted by the primary investigator on the anti-idiotype network and PRRS virus. The results of the prior work suggested the possibility that anti-idiotype could serve to induce protective immunity against PRRS virus infection in pigs. If so, an anti-idiotype-based vaccine would have the additional advantage of being easily differentiable from natural infection using conventional serologic techniques. That is, vaccinated swine would only have anti-GP5 antibodies, whereas infected swine would have antibodies against all viral epitopes. For example, pigs only possessing anti-GP5 antibodies would be serologically negative on the current commercial ELISA serological assay. A marker vaccine would, of course, provide distinct advantages in the control and elimination of PRRS.