Location: Foreign Animal Disease Research
Project Number: 1940-32000-057-26
Start Date: Jun 01, 2010
End Date: May 31, 2015
To identify the FMDV antigenic epitopes for contemporary FMDV serotype A viruses, the Agricultural Research Council- Onderstepoort Veterinary Institute (ARC-OVI) will produce recombinant monoclonal antibodies (rec-mAb), i.e. single-chain variable fragments (scFv’s) selected from a chicken immune library (Nkuku®). Rec-mAbs have been developed for a SAT2 virus and the binding mechanism of a unique binder to the SAT2 capsid has been elucidated at ARC-OVI. It is envisaged extending this study to include type A viruses as well. As such, PIADC, ARS will measure the spectra of antigenic variants and map antigenic sites within serotype A viruses using type A rec-mAb. ARS and ARC-OVI will identify and replace the potential neutralizing epitpes in the SAT2 and type A in the corresponding infectious cDNA clones and evaluate the antigenicity and usefulness in protection against FMDV. ARS and ARC-OVI will then determine the immunogenicity and protective ability of the designed vaccines, prepared from epitopes of contemporary isolates, in vivo. The newly developed ELISA will then be used to measure any changes in antigenicity. Amendment 1: A FMDV type A and SAT type specific immune phage display library will be constructed, in addition to the already available naïve library, from which FMDV specific scFvs will be panned. In order to construct the immune library, chickens will be immunized with type A and SAT antigen, the resulting antibodies which are predisposed to yield FMDV specific antibodies, will be used to produce IgY libraries. The immune libraries will then be panned against the type A and SAT antigen and the FMDV specific scFvs selected. It is envisaged that the FMDV specific scFvs obtained from both the naïve and the immune library will produce enough type A and SAT specific binders that at least 10 or more binders can be applied in an ELISA for antigen matching against panels of recent field viruses. ARS has recently developed an A24Cruzeiro-based Ad5-FMD vaccine that could be used for other important FMDV serotypes including the SAT serotype, which continues to cause FMD outbreaks in the African territories. The ARS current second generation Ad-FMDV vector will be used as the template for capsid exchanges, and the examination of potency of these vaccine candidates will be performed in collaboration with ARC-OVI.