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ARS Home » Northeast Area » Orient Point, New York » Plum Island Animal Disease Center » Foreign Animal Disease Research » Research » Research Project #431897

Research Project: Countermeasures to Control and Eradicate Foreign Animal Diseases of Swine

Location: Foreign Animal Disease Research

Project Number: 8064-32000-060-00-D
Project Type: In-House Appropriated

Start Date: Oct 11, 2016
End Date: Oct 10, 2021

Objective:
1. Develop intervention strategies to control and eradicate Classical Swine Fever (CSF), including determining immune mechanisms mediating early protection and its application in blocking infection and preventing transmission, and discovering effective CSF vaccine platforms specifically designed for disease control and eradication. Immune mechanisms mediating early protection and its application in blocking infection and preventing transmission will be developed. Studies designed to develop effective CSF vaccine platforms specifically designed for disease control and eradication will be completed. Sub-Objective 1.i: Determine immune mechanisms mediating early protection and its application in blocking infection and preventing transmission. Sub-Objective 1.ii: Discover effective CSF vaccine platforms specifically designed for disease control and eradication. 2. Develop intervention strategies to control African Swine Fever (ASF) including identify functional genomics of virus-host determinants of virulence and transmission, determining host mechanisms of ASF immune protection, determining host mechanisms of ASF disease tolerance in wild suids. Additional efforts include the identification of effective ASF vaccine platforms specifically designed for disease control and eradication, identifying the immune mechanism mediating effective homologous and heterologous protection against virus infection, researching potential antigenic vaccine markers to differentiate infected from vaccinated animals (DIVA), and identifying host cell factors that contribute to ASFV growth in cell culture conditions to inform the development of a cell line for ASFV vaccine production, and also identifying the molecular viral antigenic determinants that drive heterologous protection. Sub-Objective 2.i: Identify novel virus-host genetic determinants of virulence by systematic screening of almost all previously uncharacterized virus genes. Sub-Objective 2.ii: Discover effective ASF vaccine platforms specifically designed for disease control and eradication. Sub-Objective 2.iii: identifying the immune mechanism mediating effective homologous and heterologous protection against virus infection. Sub-Objective 2.iv: researching potential antigenic vaccine markers to differentiate infected from vaccinated animals (DIVA). Sub-Objective 2.v: identifying host cell factors that contribute to ASFV growth in cell culture conditions to inform the development of a cell line for ASFV vaccine production. 3: Determine the mechanisms that drive ASF viral evolution, including determine the molecular determinants that drive virus evolution in ASF-historical endemic settings and determine the molecular determinants that are affecting virus evolution in new ASF-endemic settings.

Approach:
The development of intervention strategies to control Classical Swine Fever will based on research of live attenuated vaccines (LAV). Research will be aimed at determining virological and immunological factors present in animals that are protected at early times post vaccination, emphasizing on expression profiles of pro-inflammatory chemical mediators (PCMs) produced the first few days after vaccination. The potential therapeutic effect of any PCMs identified will then be assessed. An evaluation of the second generation marker live attenuated vaccine (LAV) FlagT4Gv vaccine will be conducted focusing on toxicity, immunogenicity, protective effect and genetic stability. Efforts will be devoted to develop and optimize serological DIVA (to differentiate infected from vaccinated animals) tests to accompany the FlagT4G strain. Additional vaccine candidates and companion DIVA tests will also be assessed. To develop strategies to control African Swine Fever Virus (ASFV) studies will be conducted to provide information about the mechanisms of viral replication, virus host interaction and virulence in the natural host. This information will be used to identify genes that determine viral virulence that could targeted for deletion of mutation in order to yield attenuated viral strains with potential as vaccine candidates. Identification of candidate target genes will be determined through in silico analysis and/or interaction with host proteins. Full characterization of selected genes will include their interaction with host proteins, production of recombinant ASFV to assess the protein functionality in vitro and virulence during infection in swine. This research will lead to the identification of genes which may be modified or deleted to create attenuated virus strains for use in vaccine development. Strains containing two or more gene deletions/modifications will be produced and assessed to evaluate their ability to protect against homologous and heterologous virulent strains. Research will be focused in the identification of potential antigenic vaccine markers to DIVA. Studies will be focused in a systematic identification of highly immunogenic virus antigens to be used as target in the development of DIVA compatible vaccines. Efforts will also include the development of a stable cell line capable of supporting ASFV growth for use in commercial vaccine production. Host cell factors contributing to ASFV growth will be analyzed studying patterns of gene expression in susceptible versus non-susceptible cell line. As contingency to the LAV approach, experimental subunit vaccines will be tested for their ability to protect against homologous virulent ASFV. The vaccine antigens will be delivered using, a modified vaccinia Ankara virus (MVA) vector co-expressing the ASFV recombinant proteins. These vectors will be assessed in their efficiency of expressing the ASFV recombinant proteins and their immunogenicity and efficacy in protecting swine against challenge. Efforts will bedevoted to identification of host immune mechanism mediating effective protection against the challenge with homologous and heterologous viruses.