Location: Foreign Animal Disease Research2013 Annual Report
1a. Objectives (from AD-416):
This research project seeks to improve current strategies to generate Foot-and-Mouth Disease Virus (FMDV) containing specific attenuating factors and antigenic markers and evaluate their potential as vaccine candidates. We have previously developed mutations in the leader protein of FMDV which attenuated the virus for use as a vaccine candidate. There is a need to identify and introduce mutations located in other nonstructural proteins which will provide addititional attenuating factors, avoiding reversion to virulence and thereby increasing stability, to further improve efforts for vaccine development. The specific objectives are: 1. Test the virulence in swine of A24 FMDV L sap. 2. Construct and characterize in vitro, FMDV strains with mutations in the L sap in combination with deletions/mutations in the 3B coding region. 3. Test the virulence in swine of mutant FMDV L sap 3B mut strains.
1b. Approach (from AD-416):
1. Test the virulence of FMDV L sap mutant within the context of A24 which was derived from an infectious cDNA clone of FMDV field strain A 24Cruzeiro. In vivo studies will be conducted in swine utilizing different doses of A24-FMDV Lsap mutant. Clinical signs will be measured. 2. Mutant FMDV will be constructed by deleting or substituting conserved residues in the 3B region of the infectious clone of A24-FMDVL sap. Plasmids will be transcribed and resulting products analyzed. The full-length transcripts transcripts will be introduced into baby hamster kidney (BHK)-21 cells to recover infectious virus which will be characterized for in vitro activity. Mutant viruses (A24-FMDVLsap3Bmut) with an attenuated phenotype will be selected for further characterization in vivo. 3. The virulence of the mutants derived (above) will be studied in vivo in swine. Clinical signs and induction of adaptive immunity will be monitored.
3. Progress Report:
This research project seeks to develop a Foot-and-Mouth Disease (FMD) control strategy that can induce rapid and efficacious protection. Previously, ARS, PIADC developed a technique whereby mutations are introduced into the leader protein of Foot-and-Mouth Disease Virus (FMDV) in order to attenuate the virus and derive virus strains that could be used as vaccine candidates. Activities were focused on the development of new FMDV strains containing mutations in the Leader and 3B protein coding regions. New mutant viruses containing CTE and SAP mutations have been obtained and are currently being characterized. No technologies were transferred or publications produced in FY 2013.