FIG 1.

The virulence of chimeric-IRES FMDV mutants. (A) Schematic representation of the chimeric-IRES FMDV mutants and their virulence in suckling mice. Different groups of 3-day-old suckling mice were cervicodorsally inoculated with chimeric-IRES FMDV mutants or FMDV(WT) diluted to different titers of TCID₅₀. Animal deaths were scored for up to 7 days after inoculation. (B) The virulence of the mutant FMDV(R4) in pigs. Clinical signs were indicated as clinical scores, and virus yields (log₁₀ of viral RNA copies/ml) in sera and oral/nasal swabs were determined daily. Viral RNA levels in serum (○) and oral (●) and nasal (□) swab samples are expressed on the left axes, and clinical scores (bars) are expressed on the right axes.