Recipient Organization
UNIVERSITY OF ILLINOIS
2001 S. Lincoln Ave.
URBANA,IL 61801
Performing Department
Veterinary Research & Extension
Non Technical Summary
The most recent estimate of the economic impact of a porcine reproductive and respiratory syndrome (PRRS) outbreak to the American pork industry is $650 million dollars per year. Given the high incidence of new PRRS outbreaks, the development of effective intervention strategies to prevent and/or control such events to minimize the impact of PRRS is vital. Pork producers and their veterinarians have identified the development of vaccination approaches to establish effective cross-protective immunity as a topic of high priority in order to mitigate the occurrence of herd-immunity failure to PRRS virus. Herd-immunity failure occurs when a significant portion of a population fails to acquire sufficient levels of vaccine-induced protective immunity.Two reasons that could explain poor levels of vaccine-induced cross-protective immunity arethe presence of significant antigenic differences between the vaccine and the field virus anda vaccine that, although immunogenic, fails to stimulate the proper type of immunity capable of providing cross-protective (a.k.a., heterologous) immunity.Recent advances in mucosal adjuvant technology point to the increased efficacy of a properly formulated inactivated vaccine as a promising approach toimproving immune responses, protecting immunity, and increasing the breath of coverage for viruses with high levels of antigenic variation such as influenza virus. Accordingly, it is reasonable to expect that the application of these advances in mucosal vaccine technology will lead to the development of the next generation of safe and effective inactivated mucosal PRRS vaccines that should be capable of aiding in the control of virus load in the animal and its spread in the herd. Accordingly, we will prepare a killed PRRS virus vaccine that will be optimally adjuvanted. We expect that the administration of the inactivated and adjuvanted vaccinedelivered IN will elicit strong protective immunity against the genetically divergent virus.
Animal Health Component
35%
Research Effort Categories
Basic
35%
Applied
35%
Developmental
30%
Goals / Objectives
The goal of this project is to test the hypothesis that an optimally formulated inactivated PRRS virus vaccine delivered intranasally will elicit a strong cross-protective (heterologous) immunity.
Project Methods
To ascertain the influence of the adjuvant on the magnitude and quality of the adaptive immune response to the inactivated vaccine, groups of grower pigs will be immunized twice intranasally two weeks apart with different vaccine formulations. Whole blood and serum samples will be collected at 0, 7, 14, 21 and 28 days after immunization. Measuring the level of virus neutralizing antibodies in serum will assess the level of humoral immune response of the vaccinated animals. The cellular immune response to the vaccine will be assessed by measuring the interferon gamma response to recall viral antigen of peripheral blood mononuclear cells (PBMC) isolated from heparinized blood samples. To determine level of cross-reactivity to a genetically divergent PRRS virus, in both types of assays two different viruses will be used. The "atypical PRRS abortion storm" virus isolate NADC-20, which belongs to PRRSV lineage 8, and will be used to prepare the vaccine, will serve as the source of the homologous viral antigen for the assays. The second virus will be the PRRSV isolate LTX1, which belongs to lineage 1 and is related the Canadian origin 1-22-2 RFLP viruses and will serve as the source of a genetically divergent (heterologous) viral antigen to prepare the vaccine. Based on their ORF5 sequence, these two viruses have a 88% level of homology, which represents a high level of genetic divergence and can thus be considered to a heterologous.