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Research Project: Increasing the Efficacy of the Ad5-FMD Vaccine Using a Multi-Gene Delivery System

Location: Foreign Animal Disease Research

Project Number: 3022-32000-064-011-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Aug 1, 2019
End Date: Oct 1, 2023

A replication-defective human adenovirus type 5 (Ad5) vectored vaccine that delivers Foot-and-Mouth Disease Virus (FMDV) capsid and capsid processing (3C protease) genes has been shown to provide full protection against FMDV challenge in swine and cattle. However, efforts are needed to improve the efficacy, and the genetic stability during large scale production with the ultimate goal of providing early and long-lasting protection against disease in a cost-effective manner. One approach to improve the efficacy of this vaccine is to increase the amount, stability, and immunogenicity of the delivered antigen. The 3C protease strictly necessary for antigen processing in the Ad5-FMD vaccine has been shown to be toxic presumably due to in specific targeting of cellular proteins during vector production. Mutations in the FMDV 3C coding region will be incorporated to improve vector yield during vaccine production, and at the same time increase express higher amounts of antigen after vaccination. It is expected that vectors containing this mutation will provide a stronger immune response. ARS, PIADC has recently designed new Ad5 vectors that presumably display increased genetic stability by modifying genomic sequences in the vector that are also present in the cell line used for vaccine propagation. These vectors will be used to express the FMD type O cassette including the identified 3C mutation. Viruses will be characterized in vitro for expression of empty capsids and genetic stability. Candidate vectors will be selected for in vivo potency/ efficacy studies in the FMDV natural host, swine and/ or cattle. SPECIFIC OBJECTIVES 1. Evaluation of an Ad5-FMD type O vaccine containing 3C identified L127P mutation. 2. Evaluation of an Ad5-FMD vaccine that delivers simultaneously FMDV antigens and a biotherapeutic/ adjuvant Amendment 01 Start 3. Project expansion will include the identification of novel biotherapeutics that could be administered alone or in combination with FMD vaccines to improve efficacy. Specific interferon induced genes that inhibit FMDV replication will be considered as potential candidates to improve current control strategies. Alternate methods to improve efficacy by changing the route or method of Ad5 vaccine administration will also be studied. Scientists at the University of Connecticut have developed a transdermal microneedle patch that only requires a single-time administration to deliver vaccine antigens at multiple programmable time points in a pulsatile burst-release profile . The application of this technology to FMD vaccines could improve the efficacy of FMD vaccines possibly contributing to vaccine dose sparing while allowing an automatic boost at pre-determined times in livestock species of importance. 4. Identification of novel genes that could act as immunomodulators when used with FMD vaccines. 5. Evaluation of thermo/chemical stability, immunogenicity and potency/efficacy of Ad5-FMD vaccines delivered using a transdermal microneedle patch with pulsatile release capability. Amendment 01 End

1. Evaluation of an Ad5-FMD type O vaccine containing 3C mutant. Ad5-FMD O1 containing L127P mutation will be constructed and examined for virus yield and genetic stability during vaccine production. The efficacy of Ad5-O1 3C WT vs Ad5-O1 Manisa 3C L127P will be tested against FMDV infection comparatively in the natural host. 2. Evaluation of an Ad5-FMD vaccine that delivers simultaneously FMDV antigen and biotherapeutic/ adjuvant. A dicistronic vector expressing FMDV antigens and biotherapeutic/ adjuvant will be constructed. In vitro characterization of dicistronic Ad5- FMD/ biotherapeutic vaccine will be performed to assess transgenes expression and stability. The efficacy of wild type Ad5- O1 vs. Ad5-O-adjuvant dicistronic vector against FMDV infection will be tested in the natural host. Amendment 01 Start 3. Novel immunomodulators as potential adjuvants for Ad5-FMDV vaccines will be identified through analysis of unique sets of interferon stimulating genes (ISG) that inhibit FMDV replication. Previous studies have identified approximately 15 genes that selectively inhibited viral RNA replication that will now be analyzed as antivirals or immunomodulators against FMDV. Prospective candidates will be considered as adjuvants of Ad5-FMD vaccines and molecular characterization of antiviral functionality will be determined. 4. The evaluation of thermo and chemical stability, immunogenicity, potency and efficacy of Ad5-FMD vaccine delivered by a transdermal microneedle patch will be conducted. Initially the long-term thermal/chemical stability of the Ad5-Green Fluorescent Protein (GFP) vector mixed with adequate excipients will be assessed by ELISA and fluorescence analysis. Successful formulations will be tested in cell culture to ensure they retain their ability to infect cells while expressing active GFP. If successful, Ad5-FMD will be similarly formulated and thermo and chemical stability of the FMD cassette will be analyzed in vitro. Results of these tests will determine a GO/NO GO decision for further studies in animals upon amendment of the current agreement to add sufficient funds that will be needed for the pertinent research. Amendment 01 End