Construction and Evaluation of a Recombinant Foot‐and‐Mouth Disease Virus

A bstract : The South African Territories (SAT) types of foot‐and‐mouth disease virus (FMDV) show marked genomic and antigenic variation throughout sub‐Saharan Africa. This variation is geographically linked and requires the use of custom‐made vaccines. Adaptation of field isolates as vaccine strains is cumbersome, time consuming, and expensive. As an alternative to the adaptation process, the construction of recombinant FMD viruses followed by the production of conventional, inactivated vaccines utilizing these viruses is proposed. The advantage of such a strategy would be the ability to manipulate the antigenicity of these viruses by substituting the antigenic coding regions (i.e., structural proteins) of a full‐length cDNA clone of a suitable strain. A chimeric cDNA clone between types A and SAT 2 was constructed by inserting the external capsid‐coding region of the vaccine strain ZIM/7/83/2 into the genetic backbone of the A12 cDNA clone. Preliminary evaluation of the recombinant FMD virus revealed a slower growth rate for the recombinant than the parental ZIM/7/83/2, although similar antigen yields could be obtained. The chimera was found to be thermally less stable than the parental strain, suggesting it to be an inferior strain for inactivated vaccine production.