Project Number: 1940-32000-057-15
Project Type: Nonfunded Cooperative Agreement

Start Date: Jun 01, 2010
End Date: May 31, 2013

Objective:
Collaborators at the INTA laboratory, Argentina, have previously conducted studies on the nucleotide sequence of the foot-and-mouth disease virus (FMDV) outbreak prototype strain A/Arg/2001 MC267 (VFA A2001). The collaborators have derived a molecular clone of this virus so-called A2001clon. Comparison studies showed 7 amino acid changes in the polyprotein (in viral proteins VP2, VP1, 2C and 3D) and two nucleotide differences in the internal ribosome entry site (IRES) regions between the parental A2001 and A2001clon FMDVs. INTA further demonstrated that VFA A2001 was more pathogenic than VFA A2001clone in mice, however these viruses shared similar growth properties in cell culture. The main objective of this collaborative research project is to describe and characterize new viral factors of pathogenicity and virulence of FMDV. Objectives: 1. Obtain chimeric viruses based on VFA A2001clon containing the different genetic changes identified in FMDV A2001. 2. Evaluate the involvement of various genomic regions on viral virulence and pathogenicity. 3. Determine the genetic diversity of both VFA A2001 and VFA A2001clon. 4. Increase the genetic diversity of FMDV A2001clon quasispecies by performing serial passages in mice. 5. Characterize the genetic diversity and viral pathogenicity of the virus population arisen after serial passages in mice.

Approach:
To identify the differences in pathogenicity and virulence between VFA A2001 and VFA A2001clone, INTA will: 1. Construct four chimeric viruses; one in the internal ribosomal entry site, and the other in the viral proteins VP1, VP2, 2C, and 3D coding regions. 2. Determine virus plaque phenotypes, one-step growth curves in cell culture. Viral inoculation studies in mice will be performed to compare the pathogenicity and virulence among the chimeras and the original viruses. 3. Mutation frequency in both viral populations will be evaluated as a marker of genetic diversity. Nucleotide sequences of each virus will be obtained. 4. If the quasispecies complexity of VFA A2001clon is significantly lower, successive passages of the virus in suckling mice will be conducted. Analysis of the viruses that arise will show the relation between genetic diversity and pathogenicty of the isolates. Collaborators from INTA will perform all bench work and ARS, PIADC will review data and provide counseling/ technical expertise needed for the understanding of the molecular basis for virulence in the clone versus parental FMD viruses.