Location: Foreign Animal Disease Research
Project Number: 3022-32000-063-000-D
Project Type: In-House Appropriated
Start Date: Oct 11, 2021
End Date: Oct 10, 2026
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 emergency response to a disease outbreak, disease control and eradication. Sub-Objective 1.A: Determine immune mechanisms mediating early protection and its application in blocking infection and preventing transmission. Sub-Objective 1.B: Discover effective CSF vaccine platforms specifically designed for disease control and eradication. Objective 2. Develop intervention strategies to control African Swine Fever Virus (ASFV), including identify functional genomics of virus-host determinants of virulence and transmission, determining host mechanisms of ASF immune protection, and discovering effective ASF vaccine platforms specifically designed for emergency response, disease control and eradication, including the identification of antigenic markers that can be deleted from attenuated live ASV vaccine strains to differentiate infected from vaccinated animals to be used in the development of differentiation of infected from vaccinated animals (DIVA) vaccines. Sub-Objective 2.A: Identify novel virus-host genetic determinants of virulence by systematic screening of almost all previously uncharacterized virus genes. Sub-Objective 2.B: Determine host mechanisms of ASF virus immune protection. Sub-Objective 2.C: Identify antigenic markers that can be deleted from attenuated live ASF vaccine strains to differentiate infected from vaccinated animals (DIVA capability). Sub-Objective 2.D: Discover effective ASF vaccine platforms specifically designed for disease control and eradication.
Sub-Obj. 1.A: Host mechanisms of early protection will be studied by using our live attenuated vaccine (LAV) model (FlagT4Gv) that induces protection within 3 days post inoculation. Studies will analyze virological and immunological factors present in animals that are protected at early times post vaccination. Different immunological markers of cellular and humoral immune response will be evaluated at different times post vaccination and correlated with presence or absence of protection against virulent challenge. Sub-Obj. 1.B: A full evaluation of the of the second-generation marker LAV vaccine FlagT4Gv will be conducted. Activities will focus on completing the assessment of toxicity, immunogenicity, and protective effect of FlagT4G. Serological DIVA tests will be optimized and validated to differentiate infected from vaccinated animals accompanying FlagT4Gv. Sub-Obj. 2.A: The ASFV genome harbors more than 150 genes, most of which have not been characterized. The knowledge obtained from their characterization will provide critical information to understand mechanisms of virus replication, the virus and the host cell interactions, and virulence in the natural hosts. Uncharacterized virus genes will be studied. Full characterization of the selected genes will include their interaction with host proteins, the production of recombinant ASFV lacking the gene or harboring modified versions of it to assess the protein functionality in vitro, and virulence during infection in swine. This research will lead to the identification of genes which may give origin to potential attenuated vaccine candidates. Sub-Obj. 2.B: There is no consensus about the immune mechanism mediating protection in ASF. Identifying those mechanisms may improve the chances of developing more efficacious vaccines. An evaluation to determine the presence of immune mechanisms in both innate and acquired immune response in animals protected against challenge after vaccination with our LAV candidates will be done, and correlate them with the presence or absence of protection. Sub-Obj. 2.C: Experimental LAVs have been developed through genetic manipulation by deleting single virus genes involved in virulence. Depending of the epidemiological scenario it will be important to have those vaccines harbor antigenic markers that confer to them DIVA capabilities. LAVs vaccines harboring antigenic markers will be developed that will enable differentiation between vaccinated animals from those infected with field isolates. Highly antigenic genes will be identified and later deleted from the vaccine candidates to produce vaccine viruses that can be antigenically differentiated from field isolates. Sub-Obj. 2.D LAVs will be transferred to commercial partners for use as potential vaccine candidates. Actions will be focused to increase the safety profile of our LAV strains by using different combinations of additional virulence associated viral genes discovered in Sub-Objective 2.A. In addition, the development of a stable cell line capable of supporting the growth of our LAV candidate viruses will be conducted to afford the possibility of commercially develop an ASFV vaccine.