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Title: A Reverse Genetic System Provides a Powerful Tool in the Design of Foot-and-Mouth Disease Viruses with Enhanced Properties

item THERON, J
item VISSER, N
item Rieder, Aida - Elizabeth

Submitted to: European Study Group on the Molecular Biology of Picornaviruses
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/2008
Publication Date: 5/26/2008
Citation: Maree, F.F., Blignaut, B., Theron, J., Visser, N., Rieder, A.E. 2008. A reverse genetic system provides a powerful tool in the design of foot-and-mouth disease viruses with enhanced properties. European Study Group on the Molecular Biology of Picornaviruses.P 202

Interpretive Summary:

Technical Abstract: The fact that the foot-and-mouth disease viral (FMDV) RNA can be made infectious in the absence of other components of the virion allows the recovery of genetically engineered new viruses from in vitro-generated RNA molecules. We utilize infectious cDNA technology to produce recombinant FMDV, retaining cell recognition and replication characteristics indistinguishable from the parental viruses. Viable SAT1 and SAT2 genome-length constructs allowed for manipulation and replacement of major antigenic determinants, like the outer capsid-coding region, of field isolates in the genetic background of a good vaccine producing strain. Critical properties for the latter include adaptation and productivity in cultured cell lines and stability of the virus or antigen. The replication of FMDV is dependent on several factors, including cell entry via receptors, replication of the RNA genome, translation, the correct polyprotein processing by viral encoded proteases, and packaging of the RNA into virions. Consequential chimeric viruses demonstrated cell receptor preference, growth characteristics, antigenic profiles and capsid stability comparable to the parental field isolates used for the cloning process, indicating that the derived chimeras were comparable to the field strains. The chimeras represented a subpopulation of the field strains as a result of the quasispecies nature of FMDV and in at least one instance the biological properties of the field isolate were improved by the presence of the encoded replication determinants of the genome-length backbone. This imply that despite the heterogeneity observed for the 3C-coding region and cleavage sites of SAT viruses, the protease could successfully process the external capsid proteins of the individual chimeras. The reverse genetics approach also allows for altering and/or even improving the growth performance, capsid stability and antigenic profiles by changing single amino acids or replacement of known neutralising epitopes with that of a field isolate.