Partial Characterization of Temperature-Sensitive Mutants of Foot-and-Mouth Disease Virus, Oi Caseros Strain

Abstract

The preliminary characterization of four temperature-sensitive (ts) mutants of the O₁ Caseros strain of foot-and-mouth disease virus is described. Two mutants, ts 6 and ts 40, showed a very low RNA synthesis rate at nonpermissive temperature and were classified phenotypically as RNA(–). Shift-up experiments demonstrated an incapacity to organize the RNA replicative process at nonpermissive temperature. Another mutant (ts 139) behaved phenotypically as RNA( + ) and its virions were more thermolabile than the wild type virus, so the defect in this mutant is likely to be in one of its structural proteins. Finally, mutant ts 5 was phenotypically RNA( + ); its leak production at nonpermissive temperature was high, and the shift-up experiment showed a defect that was expressed either late in the replicative cycle or continuously.