Location: Foreign Animal Disease Research
Project Number: 8064-32000-056-07-S
Project Type: Specific Cooperative Agreement
Start Date: Aug 1, 2010
End Date: Dec 31, 2014
The objectives of this project are: (1) to assess the role of different regions of Classical Swine Fever Virus (CSFV) and African Swine Fever Virus (ASFV) genomes in virus virulence in swine. Amendment I; objective 2: To genetically modify CSFV and ASFV respectively that will render viruses suitable for their use as modified vaccines. Amendment III; objective 3: Conduct characterization of attenuated strain of CSFV and ASFV to be used as attenuated vaccines.
To fulfill objective 1, a set of genetically modified full-length cDNA copies of CSFV and a set of ASFV deletion mutants will be constructed from parental virulent viruses. Virulence of mutant viruses will be determined in swine relative to virulence of parental viruses. We expect that introduced changes will render viruses phenotypically different from virulent parental viruses. Relevant cellular signaling pathways altered by CSFV and ASFV infections will be revealed by further characterizing recombinant and parental viruses cycles in susceptible swine cells (i.e. primary swine macrophage cultures). The expression of relevant immunomodulatory genes will be assessed by qPCR. Identification of host cellular proteins interacting with viral proteins involved with virus virulence will be identified by means of the yeast two hybrid system. Colocalization of expressed virus proteins and interacting host proteins within infected macrophages will be performed by confocal microscopy. To fulfill objective 2, infections with wild-type and highly attenuated mutant CSFV and ASFV will be established in vivo and animals will be challenged with wild type viruses to assess the protective efficacy of recombinant viruses in exposed swine. Identification and characterization of host and viral proteins mediating disease will be an important goal in this project. Overall experimental manipulation of identified host-virus interactions may be used for developing novel tools for controlling virus infection in vivo. The characterization of attenuated strains of CSFV and ASFV will be achieved through the identification of host proteins interacting with virus proteins already known to have a role on virus attenuation. Interactions between host and virus proteins will be studied; specifically the role of the interactions in the production of disease during virus infection in the natural host. This work will be conducted to develope mutant recombinant viruses that have lost the ability to mediate this interaction.