#07-070

Complete

Date Full Report Received

11/02/2008

Date Abstract Report Received

11/02/2008

Investigation

Institution:
Primary Investigator:

As commodity markets fluctuate and producer profit margins diminish, economic loss due to infectious disease become even more important to the survivability of operations. Vaccination continues to be the most economic method for controlling infectious disease, especially ones which are difficult to control without prophylactic antibiotics. As consumer acceptance of current livestock practices change (e.g., use of antibiotics), as well as the increase in organic and antibiotic free niche markets, control of disease by preventive vaccination becomes more important. Single dose vaccines have long been sought after in human medicine to improve vaccine efficacy. The same advantage applies to animal health – a single dose vaccine would improve vaccine compliance, reduce labor costs, and, in the end, result in higher producer profits due to prevention of disease. A single dose vaccine could be readily integrated into current livestock management systems. The goal of this project was to evaluate a novel biodegradable polymer adjuvant as single dose vaccine carrier. In many cases, it is impractical in terms of labor and animal stress to immunize more than once. For most vaccines, including swine dysentery, two or three doses of a vaccine administered over several weeks are needed for complete protection. While the disease studied in this case was swine dysentery, the concept could be applied to other infectious disease agents. Using a mouse model of swine dysentery, a single dose microsphere delivered vaccine containing pepsin-digested Brachyspira hyodysenteriae antigen (PD) induced immune response to Brachyspira antigen and ameliorated inflammatory cytokine production associated with disease. A single dose vaccine containing co-polymers of CPH:SA microspheres encapsulating PD along with some unencapsulated PD was administered to crossbred grower pigs. No tissue reactivity at the injection site of polymer containing vaccine pigs was observed, whereas most of the animals receiving PD antigen incorporated into incomplete Freund’s adjuvant (a common mineral oil based carrier) had granulomatous masses at the injection site. While all of the sham-vaccinated pigs developed dysentery, three out of five pigs receiving microsphere based vaccine were protected from developing overt clinical dysentery. Further study is needed to characterize the nature of the immune response (immune regulation and/or inflammatory cytokine profile) of the microsphere vaccine. Partial protection and reduced tissue site reactivity suggest that with further refinement, biodegradable polyanhydride based single dose vaccines will be beneficial/efficacious for use in livestock animals. Principal investigator and contact: Michael J. Wannemuehler, Iowa State University, mjwannem@iastate.edu