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The goal of the current proposal is to optimize the mucosal and systemic immune responses to FMDV synthetic peptide vaccines in pigs. Peptides that include critical epitopes within the G-H loop of FMDV serotype O virus, in conjunction with three different T helper epitopes, will be tested using the intranasal route of immunization. The availability of an intranasally administered vaccine would allow large numbers of animals to be vaccinated very rapidly using minimally trained farm personnel. These vaccines will be administered using a variety of mucosal adjuvants, and will be formulated to optimize their uptake at mucosal inductive sites. Each vaccination approach will be assessed using a panel of immunological test to determine which provides the most consistent correlate of immune protection. In addition, we will determine if FMDV pseudopeptides can interfere with viral infection by blocking virus attachment, and to determine if such an approach interferes with concurrent mucosal vaccination.
NON-TECHNICAL SUMMARY: Emergency vaccines designed to protect livestock against foot-and-mouth disease virus are quite effective, however they do little by way of inducing mucosal immunity. The absence of mucosal immunity allows for the establishment of sub-clinical infections, the generation of carrier animals, and ultimately in the emergence of escape mutants. This project seeks to use synthetic peptides, administered intranasally with mucosal adjuvants, to induce secretory immunity in the upper respiratory tract of pigs.
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APPROACH: Several different FMDV-based peptide vaccines containing the immunogenic region of the G-H loop within VP1 will be synthesized in tandem with one of three T-helper cell epitopes. In addition, one peptide will include the VP1 amino acid 200-213 epitope as well. These peptides will be administered intranasally with different mucosal adjuvants, and will be formulated into microparticles or cationic/neutral lipids to optimize their uptake into mucosal lympho-epithelial tissues. Among the mucosal adjuvants to be tested are cholera toxin, synthetic CpG-containing oligonucleotides, and mutants of the heat-labile enterotoxin of E. coli. Immunological assessments will include: systemic and mucosal antibody production (ELISA); enumeration of antibody secreting cells (ELISPOT assays), T lymphocyte proliferation assays, cytokine profiles (via capture ELISA), and enumeration of activated T helper and cytotoxic T cells by flow cytometry. Using these immunological end-points, we will gain a better understanding of the immunological parameters that are correlated with protection. Vaccinated pigs will be challenged using the aerosol route of transmission at the USDA Plum Island Animal Disease Center. Additional studies will be performed using novel synthetic peptides designed to block the attachment of the virus to respiratory epithelial cells.
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PROGRESS: 2002/09 TO 2006/09<BR>
The goal of this project was to develop a safe and effective mucosal vaccine against foot-and-mouth disease virus (FMDV) to confer immunity to domestic livestock in the event of an outbreak. Recent catastrophic outbreaks in Taiwan (1997) and the United Kingdom (2001) illustrate the need for rapid and effective intervention once an outbreak is confirmed. An intranasally administered vaccine that can rapidly induce a secretory IgA anti-FMDV response within the nasal mucosa would be beneficial in this regard. Over the past year, three studies were completed: The first study was performed in pigs and was designed to test the mucosal immunogenicity of a chimeric VP1 G-H loop-containing peptide co-administered with a variety of mucosal adjuvants. In that study, four weekly intranasal vaccine doses were given in advance of a parenteral booster vaccination in a RIBI-like adjuvant to determine if mucosal vaccination had effectively primed pigs for parenteral immunity. Two proprietary E. coli heat labile enterotoxin-mutant adjuvants were found to be as effective as cholera toxin in priming parenteral responses. Overall, the anti-peptide serum immune responses were quite strong, however virus neutralization activity was only moderate. In order to better quantify the magnitude of the antibody response, we developed a slope correction method that, when paired with commercially available capture ELISA kits, yielded more precise determinations. The second mucosal vaccination study was performed in pigs using a his6-tagged, detoxified Pseudomonas exotoxin (ntPE) bearing the FMDV VP1 G-H loop that was produced in E. coli, then purified over a nickel resin. This fusion protein was tested for its ability to induce mucosal and systemic immune responses to both the ntPE and the G-H loop following intranasal administration. We found that the ntPE induced strong responses to the carrier molecule and modest responses to the G-H loop epitope.
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IMPACT: 2002/09 TO 2006/09<BR>
Emergency vaccines designed to protect livestock against foot-and-mouth disease virus are quite effective, however they do little by way of inducing mucosal immunity. The absence of mucosal immunity allows for the establishment of sub-clinical infections, the generation of carrier animals, and ultimately in the emergence of escape mutants. This project seeks to use synthetic peptides, administered intranasally with mucosal adjuvants, to induce secretory immunity in the upper respiratory tract of pigs. This approach may lead to a safe and effective method to limit the spread of disease in the event of an outbreak.