Residues within the Foot-and-Mouth Disease Virus 3D pol Nuclear Localization Signal Affect Polymerase Fidelity

In this study, we employed genetic and molecular dynamics approaches to analyze the role of individual amino acids of the FMDV 3D pol nuclear localization signal (NLS). The NLS residues were mutated to alanine using a type A full-genome cDNA clone, and the virus progeny was analyzed for defects in growth and in competition with the parental virus. We identified two mutants in 3D pol , T19A and L21A, that exhibited high rate of mutation, were sensitive to nucleotide analogs, and displayed reduced replicative fitness compared to the parental virus. Using molecular dynamics simulation, we demonstrated that residues T19 and L21 played a role in the structural configuration of the interaction network at the 3D pol palm subdomain. Cumulatively, our data suggest that the T19 and L21 3D pol amino acids are important for maintaining the fidelity of the FMDV polymerase and ensuring faithful replication of the FMDV genome.