Location: Foreign Animal Disease Research2013 Annual Report
1a. Objectives (from AD-416):
1. Develop recombinant African Swine Fever Virus (ASFV) strains by deletion of one or more viral genes already described as responsible for inducting attenuation of highly virulent ASF strains. 2. Test attenuated ASFV strains for their ability to induce protection against challenge with homologous, well-characterized, virulent ASFV isolates. 3. Evaluate patterns of heterologous protection among genetically heterogeneous ASFV strains.
1b. Approach (from AD-416):
1. Develop recombinant African Swine Fever Virus (ASFV) strains by deletion of one or more viral genes already described as responsible for inducting attenuation of highly virulent ASF strains. Critical ASFV genes that are responsible for inducing attenuation of highly virulent ASF strains will be deleted individually or as a group. This deletion should confer virus replication but not disease production. 2. Test attenuated ASFV strains for their ability to induce protection against challenge with homologous, well-characterized, virulent ASFV isolates. This will be done through: Testing strains for in vivo attenuation, testing for efficacy against homologous challenge, determination of minim protective dose response, evaluation of protection profile for at least one attenuated ASFV vaccine candidate, and the evaluation of lead vaccine candidate to induce sterile immunity. 3. Evaluate and confirm cross-protection conferred by lead vaccine candidate (obj. 2) by using genetically diverse ASFV strains.
3. Progress Report:
African Swine Fever (ASF) is a devastating disease. Although historically restricted to Africa, the disease is currently spreading in the Caucasus and Russia, menacing to enter Easter Europe in the near future. No vaccine is available, therefore the only tool to restrict the diffusion of the disease outbreak in a disease free area is by massive destruction of affected animals as well as the preventive elimination of the nearby susceptible ones. There is a need to develop a proof-of-concept, rationally designed, live attenuated ASF vaccine and to produce a vaccine with the ability to confer cross-protection for genetically diverse strains of the virus. During FY 2013, we continued the process to develop recombinant viruses lacking critical virulence genes. The original project contemplated the production of 5 recombinant virus which were lacking individually the African Swine Fever Virus (ASFV) genes 8DR, NL, UK, MGF and 9GL, using as parental virus the ASFV strain Georgia. In FY 2013, we finished producing all the recombinant plasmids, performing all the transfection infections, and plaque purification of all the recombinant viruses. Stock of purified delta 8DR, delta UK, delta 9GL and delta MGF recombinant viruses were produced. Animal experiments, to assess the degree of attenuation of these recombinant viruses, are currently in progress. No technologies were transferred in FY 2013. No publications were produced during this period.